Archives for : technology

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    SCADA Security Presentation

    This is a presentation I gave on SCADA security some time ago. It was originally set for about 2 hrs, although I broke it into 2 halves so if time permitted (or the partisipants wanted more inforamation), the backend of the presentation has many more areas and guidence relaing to SCADA, devices, environment security, etc.

    I defined the following outcomes for the presentation:

    • Broaden the awareness and necessity of security within the SCADA environment.
    • Understanding of business role in the governance/risk identification process.
    • Heighten the understanding of technology risks.

    I hope people find the material interesting and useful.

    SCADA Security Presentation Derek Grocke

    Breaking VISA PIN

    Below is an article I found recently. This one of the most comprehensive descriptions of PIN Verification Value (PVV) hacking.

    I thought I would replicate it here for my local reference.

    As comments have been made regarding the grammar used in the original text, I have corrected some of the obvious errors whilst maintaining the context of the original material.

    ——– Original Text ———-

    Have you ever wonder what would happen if you lose your credit or debit card and someone finds it. Would this person be able to withdraw cash from an ATM guessing, somehow, your PIN? Moreover, if you were who finds someone’s card would you try to guess the PIN and take the chance to get some easy money? Of course the answer to both questions should be “no”. This work does not deal with the second question, it is a matter of personal ethics. Herewith I try to answer the first question.

    All the information used for this work is public and can be freely found in Internet. The rest is a matter of mathematics and programming, thus we can learn something and have some fun. I reveal no secrets. Furthermore, the aim (and final conclusion) of this work is to demonstrate that PIN algorithms are still strong enough to provide sufficient security. We all know technology is not the weak point.

    This work analyses one of the most common PIN algorithms, VISA PVV, used by many ATM cards (credit and debit cards) and tries to find out how resistant is to PIN guessing attacks. By “guessing” I do not mean choosing a random PIN and trying it in an ATM. It is well known that generally we are given three consecutive trials to enter the right PIN, if we fail ATM keeps the card. As VISA PIN is four digit long it’s easy to deduce that the chance for a random PIN guessing is 3/10000 = 0.0003, it seems low enough to be safe; it means you need to lose your card more than three thousand times (or losing more than three thousand cards at the same time 🙂 until there is a reasonable chance of losing money.

    What I really meant by “guessing” was breaking the PIN algorithm so that given any card you can immediately know the associated PIN. Therefore this document studies that possibility, analyzing the algorithm and proposing a method for the attack. Finally we give a tool which implements the attack and present results about the estimated chance to break the system. Note that as long as other banking security related algorithms (other PIN formats such as IBM PIN or card validation signatures such as CVV or CVC) are similar to VISA PIN, the same analysis can be done yielding nearly the same results and conclusions.

    VISA PVV algorithm

    One of the most common PIN algorithms is the VISA PIN Verification Value (PVV). The customer is given a PIN and a magnetic stripe card. Encoded in the magnetic stripe is a four digit number, called PVV. This number is a cryptographic signature of the PIN and other data related to the card. When a user enters his/her PIN the ATM reads the magnetic stripe, encrypts and sends all this information to a central computer. There a trial PVV is computed using the customer entered PIN and the card information with a cryptographic algorithm. The trial PVV is compared with the PVV stored in the card, if they match the central computer returns to the ATM authorization for the transaction. See in more detail.

    The description of the PVV algorithm can be found in two documents linked in the previous page. In summary it consists in the encryption of a 8 byte (64 bit) string of data, called Transformed Security Parameter (TSP), with DES algorithm (DEA) in Electronic Code Book mode (ECB) using a secret 64 bit key. The PVV is derived from the output of the encryption process, which is a 8 byte string. The four digits of the PVV (from left to right) correspond to the first four decimal digits (from left to right) of the output from DES when considered as a 16 hexadecimal character (16 x 4 bit = 64 bit) string. If there are no four decimal digits among the 16 hexadecimal characters then the PVV is completed taken (from left to right) non decimal characters and decimalizing them by using the conversion A->0, B->1, C->2, D->3, E->4, F->5. Here is an example:

    Output from DES: 0FAB9CDEFFE7DCBA

    PVV: 0975

    The strategy of avoiding decimalization by skipping characters until four decimal digits are found (which happens to be nearly all the times as we will see below) is very clever because it avoids an important bias in the distribution of digits which has been proven to be fatal for other systems, although the impact on this system would be much lower. See also a related problem not applying to VISA PVV.

    The TSP, seen as a 16 hexadecimal character (64 bit) string, is formed (from left to right) with the 11 rightmost digits of the PAN (card number) excluding the last digit (check digit), one digit from 1 to 6 which selects the secret encrypting key and finally the four digits of the PIN. Here is an example:

    PAN: 1234 5678 9012 3445
    Key selector: 1
    PIN: 2468

    TSP: 5678901234412468

    Obviously the problem of breaking VISA PIN consists in finding the secret encrypting key for DES. The method for that is to do a brute force search of the key space. Note that this is not the only method, one could try to find a weakness in DEA, many tried, but this old standard is still in wide use (now been replaced by AES and RSA, though). This demonstrates it is robust enough so that brute force is the only viable method (there are some better attacks but not practical in our case, for a summary see LASEC memo and for the dirty details see Biham & Shamir 1990, Biham & Shamir 1991, Matsui 1993, Biham & Biryukov 1994 and Heys 2001).

    The key selector digit was very likely introduced to cover the possibility of a key compromise. In that case they just have to issue new cards using another key selector. Older cards can be substituted with new ones or simply the ATM can transparently write a new PVV (corresponding to the new key and keeping the same PIN) next time the customer uses his/her card. For the shake of security all users should be asked to change their PINs, however it would be embarrassing for the bank to explain the reason, so very likely they would not make such request.

    Preparing the attack

    A brute force attack consists in encrypting a TSP with known PVV using all possible encrypting keys and compare each obtained PVV with the known PVV. When a match is found we have a candidate key. But how many keys we have to try? As we said above the key is 64 bit long, this would mean we have to try 2^64 keys. However this is not true. Actually only 56 bits are effective in DES keys because one bit (the least significant) out of each octet was historically reserved as a checksum for the others; in practice those 8 bits (one for each of the 8 octets) are ignored.

    Therefore the DES key space consists of 2^56 keys. If we try all these keys will we find one and only one match, corresponding to the bank secret key? Certainly not. We will obtain many matching keys. This is because the PVV is only a small part (one fourth) of the DES output. Furthermore the PVV is degenerated because some of the digits (those between 0 and 5 after the last, seen from left to right, digit between 6 and 9) may come from a decimal digit or from a decimalized hexadecimal digit of the DES output. Thus many keys will produce a DES output which yields to the same matching PVV.

    Then what can we do to find the real key among those other false positive keys? Simply we have to encrypt a second different TSP, also with known PVV, but using only the candidate keys which gave a positive matching with the first TSP-PVV pair. However there is no guarantee we won’t get again many false positives along with the true key. If so, we will need a third TSP-PVV pair, repeat the process and so on.

    Before we start our attack we have to know how many TSP-PVV pairs we will need. For that we have to calculate the probability for a random DES output to yield a matching PVV just by chance. There are several ways to calculate this number and here I will use a simple approach easy to understand but which requires some background in mathematics of probability.

    A probability can always be seen as the ratio of favorable cases to possible cases. In our problem the number of possible cases is given by the permutation of 16 elements (the 0 to F hexadecimal digits) in a group of 16 of them (the 16 hexadecimal digits of the DES output). This is given by 16^16 ~ 1.8 * 10^19 which of course coincides with 2^64 (different numbers of 64 bits). This set of numbers can be separated into five categories:

    Those with at least four decimal digits (0 to 9) among the 16 hexadecimal digits (0 to F) of the DES output.

    Those with exactly only three decimal digits.

    Those with exactly only two decimal digits.

    Those with exactly only one decimal digit.

    Those with no decimal digits (all between A and F).

    Let’s calculate how many numbers fall in each category. If we label the 16 hexadecimal digits of the DES output as X1 to X16 then we can label the first four decimal digits of any given number of the first category as Xi, Xj, Xk and Xl. The number of different combinations with this profile is given by the product 6 i-1 * 10 * 6j-i-1 * 10 * 6k-j-1 * 10 * 6 l-k-1 * 10 * 1616-l where the 6’s come from the number of possibilities for an A to F digit, the 10’s come from the possibilities for a 0 to 9 digit, and the 16 comes from the possibilities for a 0 to F digit. Now the total numbers in the first category is simply given by the summation of this product over i, j, k, l from 1 to 16 but with i < j < k < l. If you do some math work you will see this equals to the product of 104/6 with the summation over i from 4 to 16 of (i-1) * (i-2) * (i-3) * 6i-4 * 16 16-i ~ 1.8 * 1019.

    Analogously the number of cases in the second category is given by the summation over i, j, k from 1 to 16 with i < j < k of the product 6i-1 * 10 * 6j-i-1 * 10 * 6k-j-1 * 10 * 616-k which you can work it out to be 16!/(3! * (16-13)!) * 103 * 6 13 = 16 * 15 * 14/(3 * 2) * 103 * 613 = 56 * 104 * 613 ~ 7.3 * 1015. Similarly for the third category we have the summation over i, j from 1 to 16 with i < j of 6 i-1 * 10 * 6j-i-1 * 10 * 616-j which equals to 16!/(2! * (16-14)!) * 102 * 614 = 2 * 103 * 615 ~ 9.4 * 1014. Again, for the fourth category we have the summation over i from 1 to 16 of 6i-1 * 10 * 616-i = 160 * 615 ~ 7.5 * 1013. And finally the amount of cases in the fifth category is given by the permutation of six elements (A to F digits) in a group of 16, that is, 616 ~ 2.8 * 1012.

    I hope you followed the calculations up to this point, the hard part is done. Now as a proof that everything is right you can sum the number of cases in the 5 categories and see it equals the total number of possible cases we calculated before. Do the operations using 64 bit numbers or rounding (for floats) or overflow (for integers) errors won’t let you get the exact result.

    Up to now we have calculated the number of possible cases in each of the five categories, but we are interested in obtaining the number of favorable cases instead. It is very easy to derive the latter from the former as this is just fixing the combination of the four decimal digits (or the required hexadecimal digits if there are no four decimal digits) of the PVV instead of letting them free. In practice this means turning the 10’s in the formula above into 1’s and the required amount of 6’s into 1’s if there are no four decimal digits. That is, we have to divide the first result by 104, the second one by 103 * 6, the third one by 102 * 62 , the fourth one by 10 * 63 and the fifth one by 64 . Then the number of favorable cases in the five categories are approximately 1.8 * 1015, 1.2 * 1012, 2.6 * 1011 , 3.5 * 1010, 2.2 * 109 respectively.

    Now we are able to obtain what is the probability for a DES output to match a PVV by chance. We just have to add the five numbers of favorable cases and divide it by the total number of possible cases. Doing this we obtain that the probability is very approximately 0.0001 or one out of ten thousand. Is it strange this well rounded result? Not at all, just have a look at the numbers we calculated above. The first category dominates by several orders of magnitude the number of favorable and possible cases. This is rather intuitive as it seems clear that it is very unlikely not having four decimal digits (10 chances out of 16 per digit) among 16 hexadecimal digits. We saw previously that the relationship between the number of possible and favorable cases in the first category was a division by 10^4, that’s where our result p = 0.0001 comes from.

    Our aim for all these calculations was to find out how many TSP-PVV pairs we need to carry a successful brute force attack. Now we are able to calculate the expected number of false positives in a first search: it will be the number of trials times the probability for a single random false positive, i.e. t * p where t = 2^56, the size of the key space. This amounts to approximately 7.2 * 10^12, a rather big number. The expected number of false positives in the second search (restricted to the positive keys found in the first search) will be (t * p) * p, for a third search will be ((t * p) * p) * p and so on. Thus for n searches the expected number of false positives will be t * p^n.

    We can obtain the number of searches required to expect just one false positive by expressing the equation t * p^n = 1 and solving for n. So n equals to the logarithm in base p of 1/t, which by properties of logarithms it yields n = log(1/t)/log(p) ~ 4.2. Since we cannot do a fractional search it is convenient to round up this number. Therefore what is the expected number of false positives if we perform five searches? It is t * p^5 ~ 0.0007 or approximately 1 out of 1400. Thus using five TSP-PVV pairs is safe to obtain the true secret key with no false positives.

    The attack

    Once we know we need five TSP-PVV pairs, how do we get them? Of course we need at least one card with known PIN, and due to the nature of the PVV algorithm, that’s the only thing we need. With other PIN systems, such as IBM, we would need five cards, however this is not necessary with VISA PVV algorithm. We just have to read the magnetic stripe and then change the PIN four times but reading the card after each change.

    It is necessary to read the magnetic stripe of the card to get the PVV and the encrypting key selector. You can buy a commercial magnetic stripe reader or make one yourself following the instructions you can find in the previous page and links therein. Once you have a reader see this description of standard magnetic tracks to find out how to get the PVV from the data read. In that document the PVV field in tracks 1 and 2 is said to be five character long, but actually the true PVV consists of the last four digits. The first of the five digits is the key selector. I have only seen cards with a value of 1 in this digit, which is consistent with the standard and with the secret key never being compromised (and therefore they did not need to move to another key changing the selector).

    I did a simple C program, getpvvkey.c, to perform the attack. It consists of a loop to try all possible keys to encrypt the first TSP, if the derived PVV matches the true PVV a new TSP is tried, and so on until there is a mismatch, in which case the key is discarded and a new one is tried, or the five derived PVVs match the corresponding true PVVs, in which case we can assume we got the bank secret key, however the loop goes on until it exhausts the key space. This is done to assure we find the true key because there is a chance (although very low) the first key found is a false positive.

    It is expected the program would take a very long time to finish and to minimize the risks of a power cut, computer hang out, etc. it does checkpoints into the file getpvvkey.dat from time to time (the exact time depends on the speed of the computer, it’s around one hour for the fastest computers now in use). For the same reason if a positive key is found it is written on the file getpvvkey.key. The program only displays one message at the beginning, the starting position taken from the checkpoint file if any, after that nothing more is displayed.

    The DES algorithm is a key point in the program, it is therefore very important to optimize its speed. I tested several implementations: libdes, SSLeay, openssl, cryptlib, nss, libgcrypt, catacomb, libtomcrypt, cryptopp, ufc-crypt. The DES functions of the first four are based on the same code by Eric Young and is the one which performed best (includes optimized C and x86 assembler code). Thus I chose libdes which was the original implementation and condensed all relevant code in the files encrypt.c (C version) and x86encrypt.s (x86 assembler version). The code is slightly modified to achieve some enhancements in a brute force attack: the initial permutation is a fixed common steep in each TSP encryption and therefore can be made just one time at the beginning. Another improvement is that I wrote a completely new setkey function (I called it nextkey) which is optimum for a brute force loop.

    To get the program working you just have to type in the corresponding place five TSPs and their PVVs and then compile it. I have tested it only in UNIX platforms, using the makefile Makegetpvvkey to compile (use the command “make -f Makegetpvvkey”). It may compile on other systems but you may need to fix some things. Be sure that the definition of the type long64 corresponds to a 64 bit integer. In principle there is no dependence on the endianness of the processor. I have successfully compiled and run it on Pentium-Linux, Alpha-Tru64, Mips-Irix and Sparc-Solaris. If you do not have and do not want to install Linux (you don’t know what you are missing 😉 you still have the choice to run Linux on CD and use my program, see my page running Linux without installing it.

    Once you have found the secret bank key if you want to find the PIN of an arbitrary card you just have to write a similar program (sorry I have not written it, I’m too lazy 🙂 that would try all 10^4 PINs by generating the corresponding TSP, encrypting it with the (no longer) secret key, deriving the PVV and comparing it with the PVV in the magnetic stripe of the card. You will get one match for the true PIN. Only one match? Remember what we saw above, we have a chance of 0.0001 that a random encryption matches the PVV. We are trying 10000 PINs (and therefore TSPs) thus we expect 10000 * 0.0001 = 1 false positive on average.

    This is a very interesting result, it means that, on average, each card has two valid PINs: the customer PIN and the expected false positive. I call it “false” but note that as long as it generates the true PVV it is a PIN as valid as the customer’s one. Furthermore, there is no way to know which is which, even for the ATM; only customer knows. Even if the false positive were not valid as PIN, you still have three trials at the ATM anyway, enough on average. Therefore the probability we calculated at the beginning of this document about random guessing of the PIN has to be corrected. Actually it is twice that value, i.e., it is 0.0006 or one out of more than 1600, still safely low.


    It is important to optimize the compilation of the program and to run it in the fastest possible processor due to the long expected run time. I found that the compiler optimization flag -O gets the better performance, thought some improvement is achieved adding the -fomit-frame-pointer flag on Pentium-Linux, the -spike flag on Alpha-Tru64, the -IPA flag on Mips-Irix and the -fast flag on Sparc-Solaris. Special flags (-DDES_PTR -DDES_RISC1 -DDES_RISC2 -DDES_UNROLL -DASM) for the DES code have generally benefits as well. All these flags have already been tested and I chose the best combination for each processor (see makefile) but you can try to fine tune other flags.

    According to my tests the best performance is achieved with the AMD Athlon 1600 MHz processor, exceeding 3.4 million keys per second. Interestingly it gets better results than Intel Pentium IV 1800 MHz and 2000 MHz (see figures below, click on them to enlarge). I believe this is due to some I/O saturation, surely cache or memory access, that the AMD processor (which has half the cache of the Pentium) or the motherboard in which it is running, manages to avoid. In the first figure below you can see that the DES breaking speed of all processors has more or less a linear relationship with the processor speed, except for the two Intel Pentium I mentioned before. This is logical, it means that for a double processor speed you’ll get double breaking speed, but watch out for saturation effects, in this case it is better the AMD Athlon 1600 MHz, which will be even cheaper than the Intel Pentium 1800 MHz or 2000 MHz.

    In the second figure we can see in more detail what we would call intrinsic DES break power of the processor. I get this value simply dividing the break speed by the processor speed, that is, we get the number of DES keys tried per second and per MHz. This is a measure of the performance of the processor type independently of its speed. The results show that the best processor for this task is the AMD Athlon, then comes the Alpha and very close after it is the Intel Pentium (except for the higher speed ones which perform very poor due to the saturation effect). Next is the Mips processor and in the last place is the Sparc. Some Alpha and Mips processors are located at bottom of scale because they are early releases not including enhancements of late versions. Note that I included the performance of x86 processors for C and assembler code as there is a big difference. It seems that gcc is not a good generator of optimized machine code, but of course we don’t know whether a manual optimization of assembler code for the other processors (Alpha, Mips, Sparc) would boost their results compared to the native C compilers (I did not use gcc for these other platforms) as it happens with the x86 processor.


    Here is an article where these techniques may have been used.

    Technology is always being challenged

    I read a very interesting paper created by the University of Massachusetts, RSA Laboratories and Innealta, Inc.<<

    This paper primarily relates to the compromise of contact less payment technologies (RFID) if the RFID and/or reader have not been implemented correctly or the solution provider has used an inappropriate type of RFID and discusses the challenges around Chip and Pin with respect to financial transactions e.g. EMV standards and compliance.

    Additionally, the paper describes a RFID relay method which is being discussed within many forums around the world and we have now begun to see equipment being produced for the RFID skimmers/clonners to use for malicious means.

    The overarching point of this paper is to use an appropriate RFID & Chip solutions which supports the security/privacy of the user and purpose of the transaction (financial or non financial)<<

    The paper can be found at

    In modern payment RFID & Chip solutions, newer devices can be used which possess a high degree of processing power and are therefore able to execute strong cryptographic methods (such as digital signatures) to protect the identification and payment information whilst the transaction is occurring.

    These systems often utilise bidirectional authentication between the RFID/Chip scanner and the RFID tag/Chip prior to performing the transaction. These methods and cryptographic algorithms are accepted and proven to work within the traditional payment markets.

    As mentioned in the paper, some solution store static digitally signed and/or encrypted data which is provided to the RFID/Chip reader when queried, but this data never changes from one transaction to another. This may allow a malicious individual to capture and re-inject the data into the reader at a later stage. The alternative to storing static digitally signed and/or encrypted data is to negotiate a key exchange at the time of the transaction in which the card/value information is encrypted and subsequently transmitted. With this method the transmitted data
    changes on every transaction and therefore even if a malicious individual was to capture the encrypted transaction data from one transaction, this would not be accepted by the reader if re-injected at a later stage.

    Although this is the case today, older RFID/Chip solutions often use technologies which are not appropriate for financial transactions and therefore may be compromised easily and in some cases without the knowledge of the card holder, merchant or acquirer.

    I find this interesting how some of these less secure solution have been approved for use by acquiring banks and the card schemes around the world (if they were told) in recent years, where it has been seen that these solutions have utilised techniques or deployment methods which can be compromised. These technologies and techniques would never be approved within the Point of Sale (PoS) or traditional banking markets.

    It can only be assumed that the need to get product to market quickly at the expense of proper testing, understanding and with due consideration to industry lessons learnt has succeeded again.

    ISO 14443 contactless card

    An international standard for proximity or contactless smart card communication

    ISO 14443 contactless card

    ISO 14443 is an international standard which describes how contactless cards and terminals should work to ensure industry-wide compatibility, for example in identity, security, payment, mass-transit and access control applications.

    ISO standards are developed by the ISO, the International Organization for Standardization. Technical committees comprising experts from the industrial, technical and business sectors develop the standards to increase levels of quality, reliability and interoperability on a global scale.

    Gemplus has always had a strong involvement in ISO definition of the chip card standards, and has been represented in the development of this international standard. The ISO 14443 is divided into 4 separate parts outlining physical characteristics, radio frequency power and signal interface, initialization and anti-collision and transmission protocol.

    Gemplus has developed a wide range of contactless payment solutions based on the ISO 14443 international standard. The speed and convenience of contactless technology has created a significant demand for this sort of solution in environments such as fast food restaurants, gas stations, public transport services, banks and many others.

    Bluetooth – Security

    Redirected from Bluetooth



    1 Bluetooth
    2 Wireless- History
    3 Wireless- Technologies
    4 Bluetooth- Technical Introduction
    5 Bluetooth- Advantages
    6 Bluetooth- Applications
    7 Bluetooth- Security Issues
    7.1 The SNARF attack
    7.2 The BACKDOOR attack
    7.3 The BLUEBUG attack
    7.4 Bluejacking
    7.5 Warnibbling
    8 Future of Bluetooth
    9 See also:
    10 Reference List


    Bluetooth is a new technology that utilises radio frequency waves as a way to communicate wirelessly between digital devices. It sets up personal area networks that incorporate all of a persons digital devices into one system for both convergence and convenience.

    Wireless- History

    Many people put the invention of [wireless] radio down to Guglielmo Marconi, who in 1895 sent the first radio telegraph transmission across the English Channel. Only twelve years later radio began being used in the public sphere. [Mathias, p.2] Up until then however, many wireless pioneers conducted trials across lakes where the antenna used to transmit the signal was longer than the distance across the lake. [Brodsky, p. 3] After its introduction the main use of wireless radio was for military communications where its first use was for the Boer War. [Flichy, p. 103] The invention of broadcast radio ensured the feasibility of wireless technologies. [Morrow, p. 2] By the 1920s, radio had become a well-recognised mass medium. [Flichy, p. 111] From the 1980s until now, wireless communications have been through several stages, from 1G (analogue signal), 2G (digital signal) and 3G (always on, faster data rate). [Lightman and Rojas, p. 3] The history of Bluetooth is a much more recent one, with the first Bluetooth-enabled products coming into existence in 2000. Named after Harald Blatand the first, king of Denmark around twelve hundred years ago, who joined the Danish and Norwegian kingdoms, Bluetooth technology is founded on this same unifying principle of being able to unite the computer and telecommunication industr[ies]. [Ganguli, p. 5] In 1994 the Ericsson Company began looking into the idea of replacing cables connecting accessories to mobile phones and computers with wireless links, and this became the main inspiration behind Bluetooth. [Morrow, p. 10]

    Wireless- Technologies

    Bluetooth is not the only wireless technology currently being developed and utilised. Other wireless technologies, including 802.11b, otherwise known as Wi-Fi, Infrared Data Association (IrDA), Ultra- Wideband Radio (UWB), and Home RF are being applied to similar technologies that Bluetooth use with mixed results. 802.11 is the most well known technology, excluding Bluetooth, and uses the same radio frequency, meaning that they are not compatible as they cause interference with each other. 802.11 is being implemented into universities in the US, Japan and China, as well as food and beverage shops where they are being used to identify students and customers. Even airports have taken up the 802.11 technology, with airports all over America, and three of Americas most prominent airlines promoting the use of it. [Lightman and Rojas, p. 202-3] Infrared Data Association is extremely inferior to that of Bluetooth. Its limitations include only being able to communicate point-to-point, needing a line of sight, and it has a speed of fifty- six kilobytes per second, whereas Bluetooth is one megabyte per second. [Ganguli, p. 17] The Ultra- Wideband Radio is superior to that of Bluetooth in that it can transmit at greater lengths (up to 70 metres), with only half of the power that Bluetooth uses. [Ganguli, p.17] HomeRF is a technology that is not very well known. It is used for data and voice communication and targeted for the residential market segment and does not serve enterprise- class WLANs, public access systems or fixed wireless Internet access. [Ganguli, p.17-18]

    Bluetooth- Technical Introduction

    Bluetooth is a short- range radio device that replaces cables with low power radio waves to connect electronic devices, whether they are portable or fixed. The Bluetooth device also uses frequency hopping to ensure a secure, quality link, and it uses ad hoc networks, meaning that it connects peer-to-peer. It can be operated worldwide and without a network because it uses the unlicensed Industrial- Scientific Medical (ISM) band for transmission that varies with a change in location. [Ganguli, p. 25-6] The Bluetooth user has the choice of point-to-point or point-to-multipoint links whereby communication can be held between two devices, or up to eight. [Ganguli, p. 96] When devices are communicating with each other they are known as piconets, and each device is designated as a master unit or slave unit, usually depending on who initiates the connection. However, both devices have the potential to be either a master or a slave. [Swaminatha and Elden, p. 49]

    Bluetooth- Advantages

    There are many advantages to using Bluetooth wireless technologies including the use of a radio frequency, the inexpensive cost of the device, replacing tedious cable connections, the low power use and implemented security measures. The use of an unlicensed radio frequency ensures that users do not need to gain a license in order to use it. Unlike Infrared which needs to have a line of sight in order to work, Bluetooth radio waves are omnidirectional and do not need a clear path. The device itself is relatively cheap and easy to use, one can be bought for around ten American dollars, and this price is currently decreasing. Compare this to the expensive cost of implementing hundreds of cables and wires into an office and there is no competition. Of course, this is the main reason for the take -up in Bluetooth -enabled devices; it does away with cables. Another of Bluetooths advantages is its low power use, ensuring that battery operated devices such as mobile phones and personal digital assistants wont have their battery life drained with the use of it. This low power consumption also guarantees minimal interruption from other radio operated and wireless devices that operate at a higher power. Bluetooth has several enabled security measures that ensures a level of privacy and security, including frequency hopping, whereby the device changes radio frequency sixteen hundred times per second. Also within the security tools are encryption and authentification mechanisms that guarantee little interference by unauthorised hackers. [Ganguli, p. 330] One of the best advantages of Bluetooth devices, especially the hands free device that connects to a mobile phone, is that it removes radiation from the brain region. [Tsang, p.1]

    Bluetooth- Applications

    The applications that are in development or current use for the Bluetooth technology include such areas as automotive, medical, industrial equipment, output equipment, digital -still cameras, computers, and communications systems. [Lightman and Rojas, p. 201] Bluetooth is an ad hoc network user, and therefore it may be used for social networking, i.e. people can meet and share files or link their Bluetooth devices together to play games or other such activities. [Smyth, p. 70] Using Bluetooth, a mobile phone can become a three- way phone, where at home it connects to a landline for cheaper calls, on the move it acts as a mobile phone and when it comes in contact with another Bluetooth-enabled phone it acts as a walkie- talkie. This walkie- talkie option allows for free interaction and communication, as Bluetooth is not connected to any telecommunications network. [Gupta, p.1] Bluetooth also allows automatic synchronization of your desktop, mobile computer, notebook and your mobile phone for the user to have all of their data managed as one. [Gupta, p.1]

    Bluetooth- Security Issues

    Bluetooth has several threats which range in level of risk and how widespread the action is. These threats have the ability to provide criminals with sensitive information on both corporate and personal levels. The only way to avoid such threats is for manufacturers, distributors, and consumers to be provided with more information on how they are committed, current attack activity and how to combat them. This information can be used on a technical level for manufacturers, it can be used by distributors at retail levels to teach consumers the risks and it can be used directly by consumers to be aware of the threats. The outcome of such research will allow end users of Bluetooth products to have an upper hand in this wireless warfare. Bluetooth security is in early stages with regards to both the attackers, their techniques and consumers understanding of these attacks. Some research has been conducted into what the attackers are doing and how they do it. Adam Laurie of A.L Digital Ltd is leading the research race in Bluetooth security and is often linked to academic resources. Laurie’s research has uncovered the following capabilities of Bluetooth attacks:

    • Confidential data such as the entire phone book, calender and the phone’s IMEI.
    • Complete memory contents of some mobile phones can be accessed by a previously trusted (“paired”) device that has since been removed from the trusted list.
    • Access can be gained to the AT command set of the device, giving full access to the higher level commands and channels, such as data, voice and messaging.

    Attacks on Bluetooth devices at this stage are relatively new to consumers, and therefore are not widely seen as a real threat. Attacks such as the Bluejack attack are probably more recognised by consumers due to its perceived humorous and novelty nature as well as the ease to Bluejack someone. Users who allow their phone to be Bluejacked open the door to more serious attacks, such as the Backdoor attack which have a low level of awareness amongst consumers as attackers can attach to the device with out the users knowledge. Corporations are starting to understand the risks Bluetooth devices pose, Michael Ciarochi (in Brewin 2004) stated that ‘Bluetooth radios were included in laptop PCs that were being configured by an IT Engineer. It raises the possibility of opening a wireless back door into data stored on the PCs. Such a security weakness would be extremely attractive to hackers. Although Bluetooth invites hackers to such attacks; Bluetooth Venders are playing down the risks, Brewin (2004) said that ‘Bluetooth advocates last week dismissed growing security fears about the short-range wireless technology, saying any flaws are limited to a few mobile-phone models. They also detailed steps that users can take to secure Bluetooth devices’. There are many methods of Bluetooth attacks, the Snarf, the Backdoor, Bluebug, Bluejack and Warnibbling attack are the only recognised attacks at this early stage. Below are explanations of such attacks.

    The SNARF attack

    It is possible for attackers to connect to the device without alerting the user, once in the system sensitive data can be retrieved, such as the phone book, business cards, images, messages and voice messages.

    Local Copy: BlueSnarf_CeBIT2004.pdf

    The BACKDOOR attack

    The backdoor attack is a higher concern for Bluetooth users; it allows attackers to establishing a trust relationship through the “pairing” mechanism, but ensuring that the user can not see the target’s register of paired devices. In doing this attackers have access to all the data on the device, as well as access to use the modem or internet; WAP and GPRS gateways may be accessed without the owner’s knowledge or consent.

    The BLUEBUG attack

    This attack gives access to the AT command set, in other words it allows the attacker to make premium priced phone calls, allows the use of SMS, or connection the internet. Attackers can not only use the device for such fraudulent exercises it also allows identity theft to impersonate the user.


    Dibble (2004) explained that ‘Just as SMS was spawned, there’s a new craze that’s spreading across parts of Europe. Reportedly, it’s more prominent in the UK, but popular elsewhere too’. Bluejacking allows attackers to send messages to strangers in public via Bluetooth. When the phones ‘pair’ the attacked can write a message to the user. Although it may seem harmless at first, there is a downside. Once connected the attacker may then have access to any data on the users Bluetooth device, which has obvious concerns. Powell (2004: 22) explained that ‘Users can refuse any incoming message or data, so Bluejackers change their username to a short barb or compliment to beat you to the punch. For example, you might receive something along the lines of “Incoming message from: Dude, you’ve been Bluejacked.” Or, “Incoming message from: ROI is overrated.” Bluejacking is regarded as a smaller threat to Bluetooth as users being attacked are aware they have been Bluejacked. This does not mean however that they are aware that sensitive information is being accessed and used in a malicious manner.


    Warnibbling is a hacking technique using Redfang, or similar software that allows hackers to reveal corporate or personal sensitive information. Redfang allows hackers to find Bluetooth devices in the area, once found, the software takes you through the process of accessing any data that is stored on that device. Redfang also allows non-discoverable devices to be found. Whitehouse explains when testing Redfang ‘One of the first obstacles we had to overcome was the discovery of non-discoverable devices (it was surprising to see the number of devices that dont by default implement this security measure)’.

    Future of Bluetooth

    Further information, and somewhat speculation is required for consumers and Bluetooth stakeholders on the future of Bluetooth. Such information will provide a clearer understanding of why security of Bluetooth must be improved. Luo and Lee (2004) provide a short term prediction of where Bluetooth is heading, Europe and Asian countries already offer electronic newspapers, subway tickets, and car parking fees via wireless devices. Collins (2003) says that Bluetooth devices ‘appear to be more secure than 802.11 wireless LANs. However, this situation may not last, as the Bluetooth technology becomes more widespread and attracts greater interest from the hacking community’.

    See also:

    Reference List

    • Brodsky, I. (1995) Wireless: The Revolution in Personal Telecommunications, Massachussetts, USA: Artech House Inc, ISBN 0890067171 (Erin Watson)
    • Collins, G. (2003) Bluetooth Security. [Online], Available: Academic Search Elite, ISSN:0360-5280 [Accessed 6/9/04]. (Ben Henzell)
    • Dibble, T (2003) ‘Bluejack city: a new wireless craze is spreading through Europe’ [Online]. Available: [Accessed 4/8/04. (Ben Henzell)
    • Finn, E. (2004) Be carefull when you cut the cord. Popular Science [Online], vol. 264, issue. 5, p30. Available: Ebsco Host: Academic Search Elite, ISSN:0161-7370 [Accessed 6/9/04]. (Ben Henzell)
    • Flichy, P. (1995) Dynamics of Modern Communication, London: Sage Publications, ISBN 0803978502 (Erin Watson)
    • Ganguli, M. (2002) Getting Started with Bluetooth, Ohio: Premier Press, ISBN 1931841837 (Erin Watson)
    • Gupta, P. 1999. Bluetooth Technology: What are the Applications?. (accessed August 23, 2004). (Erin Watson)
    • Laurie, B & L (2003) Serious flaws in Bluetooth security lead to disclosure of personal data [Online]. Available: [Accessed 4th Aug 2004]. (Ben Henzell)
    • Lightman, A. and Rojas, W. (2002) Brave New Unwired World, New York, USA: John Wiley and Sons, Inc., ISBN 0471441104 (Erin Watson)
    • Luo, X. Lee, C. (2004). Micropayments in Wireless M-Commerce: Issues, Security, and Trend[Online]. Available: [Accessed 4/8/2004] (Ben Henzell)
    • Morrow, R. (2002) Bluetooth Operation and Use, New York, USA: The McGraw- Hill Companies, ISBN 007138779X (Erin Watson)
    • Powell, W. (2004) The Wild Wild Web T+D [Online], Vol. 58, issue. 1, p22. Available: Academic Search Elite, ISSN:1535-7740 [Accessed 6/9/04]. (Ben Henzell)
    • Smyth, P. (ed.)(2004) Mobile and Wireless Communications: Key Technologies and Future Applications, London, UK: The Institute of Electrical Engineers, ISBN 0863413684 (Erin Watson)
    • Swaminatha, T. and Elden, C. (2003) Wireless Security and Privacy: Best Practices and Design Techniques, Massachussetts, USA: Pearson Education, Inc., ISBN 0201760347 (Erin Watson)
    • Tsang, W. et al. Date unknown. Bluetooth Applications. (accessed August 23, 2004). (Erin Watson)
    • Whitehouse, O. (2003).’War Nibbling: Bluetooth Insecurity’ [Online]. Available: [Accessed 9/8/04] (Ben Henzell)

    Erin Watson 08:47, 8 Sep 2004 (EST) –nhenzell 12:30, 8 Sep 2004 (EST)

    Serious flaws in bluetooth security lead to disclosure of personal data




    In November 2003, Adam Laurie of A.L. Digital Ltd. discovered that there are serious flaws in the authentication and/or data transfer mechanisms on some bluetooth enabled devices. Specifically, three vulnerabilities have been found:

    Firstly, confidential data can be obtained, anonymously, and without the owner’s knowledge or consent, from some bluetooth enabled mobile phones. This data includes, at least, the entire phone book and calendar, and the phone’s IMEI.

    Secondly, it has been found that the complete memory contents of some mobile phones can be accessed by a previously trusted (“paired”) device that has since been removed from the trusted list. This data includes not only the phonebook and calendar, but media files such as pictures and text messages. In essence, the entire device can be “backed up” to an attacker’s own system.

    Thirdly, access can be gained to the AT command set of the device, giving full access to the higher level commands and channels, such as data, voice and messaging. This third vulnerability was identified by Martin Herfurt, and they have since started working together on finding additional possible exploits resulting from this vulnerability.

    Finally, the current trend for “Bluejacking” is promoting an environment which puts consumer devices at greater risk from the above attacks.

    The SNARF attack:
    It is possible, on some makes of device, to connect to the device without alerting the owner of the target device of the request, and gain access to restricted portions of the stored data therein, including the entire phonebook (and any images or other data associated with the entries), calendar, real-time clock, business card, properties, change log, IMEI (International Mobile Equipment Identity [6], which uniquely identifies the phone to the mobile network, and is used in illegal phone ‘cloning’). This is normally only possible if the device is in “discoverable” or “visible” mode, but there are tools available on the Internet that allow even this safety net to be bypassed[4]. Further details will not be released at this time (see below for more on this), but the attack can and will be demonstrated to manufacturers and press if required.

    The BACKDOOR attack:
    The backdoor attack involves establishing a trust relationship through the “pairing” mechanism, but ensuring that it no longer appears in the target’s register of paired devices. In this way, unless the owner is actually observing their device at the precise moment a connection is established, they are unlikely to notice anything untoward, and the attacker may be free to continue to use any resource that a trusted relationship with that device grants access to (but note that so far we have only tested file transfers). This means that not only can data be retrieved from the phone, but other services, such as modems or Internet, WAP and GPRS gateways may be accessed without the owner’s knowledge or consent. Indications are that once the backdoor is installed, the above SNARF attack will function on devices that previously denied access, and without the restrictions of a plain SNARF attack, so we strongly suspect that the other services will prove to be available also.

    The BLUEBUG attack:
    The bluebug attack creates a serial profile connection to the device, thereby giving full access to the AT command set, which can then be exploited using standard off the shelf tools, such as PPP for networking and gnokii for messaging, contact management, diverts and initiating calls. With this facility, it is possible to use the phone to initiate calls to premium rate numbers, send sms messages, read sms messages, connect to data services such as the Internet, and even monitor conversations in the vicinity of the phone. This latter is done via a voice call over the GSM network, so the listening post can be anywhere in the world. Bluetooth access is only required for a few seconds in order to set up the call. Call forwarding diverts can be set up, allowing the owner’s incoming calls to be intercepted, either to provide a channel for calls to more expensive destinations, or for identity theft by impersonation of the victim.

    Although known to the technical community and early adopters for some time, the process now known as “Bluejacking”[1] has recently come to the fore in the consumer arena, and is becoming a popular mechanism for exchanging anonymous messages in public places. The technique involves abusing the bluetooth “pairing”[2] protocol, the system by which bluetooth devices authenticate each other, to pass a message during the initial “handshake” phase. This is possible because the “name” of the initiating bluetooth device is displayed on the target device as part of the handshake exchange, and, as the protocal allows a large user defined name field – up to 248 characters – the field itself can be used to pass the message. This is all well and good, and, on the face of it, fairly harmless, but, unfortunately, there is a down side. There is a potential security problem with this, and the more the practice grows and is accepted by the user community, and leveraged as a marketing tool by the vendors, the worse it will get. The problem lies in the fact that the protocol being abused is designed for information exchange. The ability to interface with other devices and exchange, update and synchronise data, is the raison d’être of bluetooth. The bluejacking technique is using the first part of a process that allows that exchange to take place, and is therefore open to further abuse if the handshake completes and the “bluejacker” successfully pairs with the target device. If such an event occurs, then all data on the target device becomes available to the initiator, including such things as phone books, calendars, pictures and text messages. As the current wave of PDA and telephony integration progresses, the volume and quality of such data will increase with the devices’ capabilities, leading to far more serious potential compromise. Given the furore that irrupted when a second-hand Blackberry PDA was sold without the previous owner’s data having been wiped[3], it is alarming to think of the consequences of a single bluejacker gathering an entire corporate staff’s contact details by simply attending a conference or camping outside their building or in their foyer with a bluetooth capable device and evil intent. Of course, corporates are not the only potential targets – a bluejacking expedition to, say, The House of Commons, or The US Senate, could provide some interesting, valuable and, who’s to say, potentially damaging or compromising data.<<<


    The above may sound alarmist and far fetched, and the general reaction would probably be that most users would not be duped into allowing the connection to complete, so the risk is small. However, in today’s society of instant messaging, the average consumer is under a constant barrage of unsolicited messages in one form or another, whether it be by SPAM email, or “You have won!” style SMS text messages, and do not tend to treat them with much suspicion (although they may well be sceptical about the veracity of the offers). Another message popping up on their ‘phone saying something along the lines of “You have won 10,000 pounds! Enter this 4 digit PIN number and then dial 0900-SUCKER to collect your prize!” is unlikely to cause much alarm, and is more than likely to succeed in many cases.

    Workarounds and fixes
    We are not aware of any workarounds for the SNARF or BLUEBUG attacks at this time, other than to switch off bluetooth. For permanent fixes, see the ‘Fixes’ section at the bottom of the page.

    To permanently remove a pairing, and protect against future BACKDOOR attacks, it seems you must perform a factory reset, but this will, of course, erase all your personal data.

    To avoid Bluejacking, “just say no”. :)

    The above methods work to the best of our knowledge, but, as the devices affected are running closed-source proprietary software, it not possible to verify that without the collaboration of the manufacturers. We therefore make no claims as to the level of protection they provide, and you must continue to use bluetooth at your own risk.

    Who’s Vulnerable
    To date the quantity of devices tested is not great. However, due to the fact that they are amongst the most popular brands, we still consider the affected group to be large. It is also assumed that there are shared implementations of the bluetooth stack, so what affects one model is likely to affect others. This table is accurate to the best of our knowledge, but without the cooperation of the manufacturers (which we currently do not have), it is not possible to conduct more extensive validation.

    The devices known to be vulnerable at this time are:

    Vulnerability Matrix (* = NOT Vulnerable)
    MakeModelFirmware RevBACKDOORSNARF when VisibleSNARF when NOT VisibleBUG
    Sony EricssonR520m20R2G?YesNo?
    Sony EricssonT68i20R1B
    Sony EricssonT61020R1A081
    Sony EricssonT61020R1A081???Yes
    Sony EricssonZ1010??Yes??
    Sony EricssonZ60020R2C007
    Nokia7650?YesNo (+)?No
    * SiemensS55?NoNoNoNo
    * SiemensSX1?NoNoNoNo
    MotorolaV600 (++)?NoNoNoYes
    MotorolaV80 (++)?NoNoNoYes

    + We now believe the 7650 is only vulnerable to SNARF if it has already been BACKDOORed.
    ++ The V600 and V80 are discoverable for only 60 seconds, when first powered on or when this feature is user selected, and the window for BDADDR discovery is therefore very small. Motorola have stated that they will correct the vulnerability in current firmware.

    What is the Philosophy of Full Disclosure, and why are we providing the tools and detailing the methods that allow this to be done? The reasoning is simple – by exposing the problem we are achieving two goals: firstly, to alert users that the dangers exist, in order that they can take their own precautions against compromise, and secondly, to put pressure on manufacturers to rectify the situation. Consumers have a right to expect that their confidential data is treated as such, and is not subject to simple compromise by poorly implemented protocols on consumer devices. Manufacturers have a duty of care to ensure that such protection is provided, but, in practice, commercial considerations will often take precedence, and, given the choice, they may choose to simply supress or hide the problem, or, even worse, push for laws that prevent the discovery and/or disclosure of such flaws[5]. In our humble opinion, laws provide scant consumer protection against the lawless.

    After 13 months, and in consideration of the fact that affected manufacturers had acknowledged the issues and made updated firmware available, Full Disclosure took place at the Chaos Computer Club’s annual congress – 21C3, in Berlin, 2004.

    Slides from the disclosure talk can be found here:

    Proof of concept utilities have been developed, but are not yet available in the wild. They are:

    • bluestumbler – Monitor and log all visible bluetooth devices (name, MAC, signal strength, capabilities), and identify manufacturer from MAC address lookup.
    • bluebrowse – Display available services on a selected device (FAX, Voice, OBEX etc).
    • bluejack – Send anoymous message to a target device (and optionally broadcast to all visible devices).
    • bluesnarf – Copy data from target device (everything if pairing succeeds, or a subset in other cases, including phonebook and calendar. In the latter case, user will not be alerted by any bluejack message).
    • bluebug – Set up covert serial channel to device.
      Tools will not be released at this time, so please do not ask. However, if you are a bona-fide manufacturer of bluetooth devices that we have been otherwise unable to contact, please feel free to get in touch for more details on how you can identify your device status.

    The above vulnerabilities were discovered by Adam Laurie, during the course of his work with A.L. Digital, in November 2003, and this announcement was prepared thereafter by Adam and Ben Laurie for immediate release.

    Adam Laurie is Managing Director and Chief Security Officer of A.L. Digital Ltd.

    Ben Laurie is Technical Director of A.L. Digital, and author of Apache-SSL and contributor to many other open source projects, too numerous to expand on here.

    A.L. Digital Ltd. are the owner operators of The Bunker, the world’s most secure data centre(s).


    Further information relating to this disclosure will be updated at






    • bluesniff
    • btscanner
    • redfang



    Bluetooth Wireless Specification


    This article is about the Bluetooth wireless specification. For King Harold Bluetooth, see Harold I of Denmark

    Bluetooth is an industrial specification for wireless personal area networks (PANs).

    Bluetooth provides a way to connect and exchange information between devices like personal digital assistants (PDAs), mobile phones, laptops, PCs, printers and digital cameras via a secure, low-cost, globally available short range radio frequency.

    Bluetooth lets these devices talk to each other when they come in range, even if they’re not in the same room, as long as they are within 10 metres (32 feet) of each other.

    The spec was first developed by Ericsson, later formalised by the Bluetooth Special Interest Group (SIG). The SIG was formally announced on May 20, 1999. It was established by Sony Ericsson, IBM, Intel, Toshiba and Nokia, and later joined by many other companies as Associate or Adopter members.

    Table of contents

    * 1 About the name
    * 2 General information
    o 2.1 Embedded Bluetooth
    * 3 Features by version
    o 3.1 Bluetooth 1.0 and 1.0B
    o 3.2 Bluetooth 1.1
    o 3.3 Bluetooth 1.2
    o 3.4 Bluetooth 2.0
    * 4 Future Bluetooth uses
    * 5 Security concerns
    * 6 Bluetooth profiles
    * 7 See also
    * 8 External links

    About the name

    The system is named after a Danish king Harald Blåtand (<arold Bluetooth in English), King of Denmark and Norway from 935 and 936 respectively, to 940 known for his unification of previously warring tribes from Denmark, Norway and Sweden. Bluetooth likewise was intended to unify different technologies like computers and mobile phones. The Bluetooth logo merges the Nordic runes for H and B.

    General information


    A typical Bluetooth mobile phone headset

    The latest version currently available to consumers is 2.0, but few manufacturers have started shipping any products yet. Apple Computer, Inc. offered the first products supporting version 2.0 to end customers in January 2005. The core chips have been available to OEMs (from November 2004), so there will be an influx of 2.0 devices in mid-2005. The previous version, on which all earlier commercial devices are based, is called 1.2.

    Bluetooth is a wireless radio standard primarily designed for low power consumption, with a short range (up to 10 meters [1], ) and with a low-cost transceiver microchip in each device.

    It can be used to wirelessly connect peripherals like printers or keyboards to computers, or to have PDAs communicate with other nearby PDAs or computers.

    Cell phones with integrated Bluetooth technology have also been sold in large numbers, and are able to connect to computers, PDAs and, specifically, to handsfree devices. BMW was the first motor vehicle manufacturer to install handsfree Bluetooth technology in its cars, adding it as an option on its 3 Series, 5 Series and X5 vehicles. Since then, other manufacturers have followed suit, with many vehicles, including the 2004 Toyota Prius and the 2004 Lexus LS 430. The Bluetooth car kits allow users with Bluetooth-equipped cell phones to make use of some of the phone’s features, such as making calls, while the phone itself can be left in a suitcase or in the boot/trunk, for instance.

    The standard also includes support for more powerful, longer-range devices suitable for constructing wireless LANs.

    A Bluetooth device playing the role of “master” can communicate with up to 7 devices playing the role of “slave”. At any given instant in time, data can be transferred between the master and one slave; but the master switches rapidly from slave to slave in a round-robin fashion. (Simultaneous transmission from the master to multiple slaves is possible, but not used much in practice). These groups of up to 8 devices (1 master and 7 slaves) are called piconets.

    The Bluetooth specification also allows connecting two or more piconets together to form a scatternet, with some devices acting as a bridge by simultaneously playing the master role in one piconet and the slave role in another piconet. These devices have yet to come, though are supposed to appear within the next two years.

    Any device may perform an “inquiry” to find other devices to which to connect, and any device can be configured to respond to such inquiries.

    Pairs of devices may establish a trusted relationship by learning (by user input) a shared secret known as a “passkey”. A device that wants to communicate only with a trusted device can cryptographically authenticate the identity of the other device. Trusted devices may also encrypt the data that they exchange over the air so that no one can listen in.

    The protocol operates in the license-free ISM band at 2.45 GHz. In order to avoid interfering with other protocols which use the 2.45 GHz band, the Bluetooth protocol divides the band into 79 channels (each 1 MHz wide) and changes channels up to 1600 times per second. Implementations with versions 1.1 and 1.2 reach speeds of 723.1 kbit/s. Version 2.0 implementations feature Bluetooth Enhanced Data Rate (EDR), and thus reach 2.1 Mbit/s. Technically version 2.0 devices have a higher power consumption, but the three times faster rate reduces the transmission times, effectively reducing consumption to half that of 1.x devices (assuming equal traffic load).

    Bluetooth differs from Wi-Fi in that the latter provides higher throughput and covers greater distances but requires more expensive hardware and higher power consumption. They use the same frequency range, but employ different multiplexing schemes. While Bluetooth is a cable replacement for a variety of applications, Wi-Fi is a cable replacement only for local area network access. A glib summary is that Bluetooth is wireless USB whereas Wi-Fi is wireless Ethernet.

    Many USB Bluetooth adapters are available, some of which also include an IrDA adapter.

    Embedded Bluetooth

    Bluetooth devices and modules are increasingly being made available which come with an embedded stack and a standard UART port. The UART protocol can be as simple as the industry standard AT protocol, which allows the device to be configured to cable replacement mode. This means it now only takes a matter of hours (instead of weeks) to enable legacy wireless products that communicate via UART port.

    Features by version

    Bluetooth 1.0 and 1.0B

    Versions 1.0 and 1.0B had numerous problems and the various manufacturers had great difficulties in making their products interoperable. 1.0 and 1.0B also had mandatory Bluetooth Hardware Device Address (BD_ADDR) transmission in the handshaking process, rendering anonymity impossible at a protocol level, which was a major set-back for services planned to be used in Bluetooth environments, such as Consumerism.

    Bluetooth 1.1

    In version 1.1 many errata found in the 1.0B specifications were fixed. There was added support for non-encrypted channels.

    Bluetooth 1.2

    This version is backwards compatible with 1.1 and the major enhancements include

    • Adaptive Frequency Hopping (AFH), which improves resistance to radio interference by avoiding using crowded frequencies in the hopping sequence
    • Higher transmission speeds in practice
    • extended Synchronous Connections (eSCO), which improves voice quality of audio links by allowing retransmissions of corrupted packets.
    • Received Signal Strength Indicator (RSSI)
    • Host Controller Interface (HCI) support for 3-wire UART
    • HCI access to timing information for Bluetooth applications.

    Bluetooth 2.0

    This version is backwards compatible with 1.x and the major enhancements include

    • Non-hopping narrowband channel(s) introduced. These are faster but have been criticised as defeating a built-in security mechanism of earlier versions; however frequency hopping is hardly a reliable security mechanism by today’s standards. Rather, Bluetooth security is based mostly on cryptography.
    • Broadcast/multicast support. Non-hopping channels are used for advertising Bluetooth service profiles offered by various devices to high volumes of Bluetooth devices simultaneously, since there is no need to perform handshaking with every device. (In previous versions the handshaking process takes a bit over one second.)
    • Enhanced Data Rate (EDR) of 2.1 Mbit/s.
    • Built-in quality of service.
    • Distributed media-access control protocols.
    • Faster response times.
    • Halved power consumption due to shorter duty cycles.

    Future Bluetooth uses

    One of the ways Bluetooth technology may become useful is in Voice over IP. When VOIP becomes more widespread, companies may find it unnecessary to employ telephones physically similar to today’s analogue telephone hardware. Bluetooth may then end up being used for communication between a cordless phone and a computer listening for VOIP and with an infrared PCI card acting as a base for the cordless phone. The cordless phone would then just require a cradle for charging. Bluetooth would naturally be used here to allow the cordless phone to remain operational for a reasonably long period.

    Security concerns

    In November 2003, Ben and Adam Laurie from A.L. Digital Ltd. discovered that serious flaws in Bluetooth security lead to disclosure of personal data (see It should be noted however that the reported security problems concerned some poor implementations of Bluetooth, rather than the protocol itself.

    In a subsequent experiment, Martin Herfurt from the was able to do a field-trial at the CeBIT fairgrounds showing the importance of the problem to the world. A new attack called BlueBug was used for this experiment.

    In April 2004, security consultants @Stake revealed a security flaw that makes it possible to crack into conversations on Bluetooth based wireless headsets by reverse engineering the PIN.

    This is one of a number of concerns that have been raised over the security of Bluetooth communications. In 2004 the first purported virus using Bluetooth to spread itself among mobile phones appeared for the Symbian OS. The virus was first described by Kaspersky Labs and requires users to confirm the installation of unknown software before it can propagate. The virus was written as a proof-of-concept by a group of virus writers known as 29a and sent to anti-virus groups. Because of this, it should not be regarded as a security failure of either Bluetooth or the Symbian OS. It has not propagated ‘in the wild’.

    In August 2004, a world-record-setting experiment (see also Bluetooth sniping) showed that with directional antennas the range of class 2 Bluetooth radios could be extended to one mile. This enables attackers to access vulnerable Bluetooth-devices from a distance beyond expectation.

    Bluetooth uses the SAFER+ algorithm for authentication and key generation.

    Bluetooth profiles

    In order to use Bluetooth, a device must be able to interpret certain Bluetooth profiles. These define the possible applications. Following profiles are defined:

    • Generic Access Profile (GAP)
    • Service Discovery Application Profile (SDAP)
    • Cordless Telephony Profile (CTP)
    • Intercom Profile (IP)
    • Serial Port Profile (SPP)
    • Headset Profile (HSP)
    • Dial-up Networking Profile (DUNP)
    • Fax Profile
    • LAN Access Profile (LAP)
    • Generic Object Exchange Profile (GOEP)
    • Object Push Profile (OPP)
    • File Transfer Profile (FTP)
    • Synchronisation Profile (SP)

    This profile allows synchronisation of Personal Information Manager (PIM) items. As this profile originated as part of the infra-red specifications but has been adopted by the Bluetooth SIG to form part of the main Bluetooth specification, it is also commonly referred to as IrMC Synchronisation.

    • Hands-Free Profile (HFP)
    • Human Interface Device Profile (HID)
    • Hard Copy Replacement Profile (HCRP)
    • Basic Imaging Profile (BIP)
    • Personal Area Networking Profile (PAN)
    • Basic Printing Profile (BPP)
    • Advanced Audio Distribution Profile (A2DP)
    • Audio Video Remote Control Profile (AVRCP)
    • SIM Access Profile (SAP)

    Compatibility of products with profiles can be verified on the Bluetooth Qualification website.

    See also

    External links