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32
Keying hash functions for message authentication
, 1996
"... The use of cryptographic hash functions like MD5 or SHA for message authentication has become a standard approach inmanyInternet applications and protocols. Though very easy to implement, these mechanisms are usually based on ad hoc techniques that lack a sound security analysis. We present new cons ..."
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Cited by 478 (38 self)
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The use of cryptographic hash functions like MD5 or SHA for message authentication has become a standard approach inmanyInternet applications and protocols. Though very easy to implement, these mechanisms are usually based on ad hoc techniques that lack a sound security analysis. We present new constructions of message authentication schemes based on a cryptographic hash function. Our schemes, NMAC and HMAC, are proven to be secure as long as the underlying hash function has some reasonable cryptographic strengths. Moreover we show, in a quantitativeway, that the schemes retain almost all the security of the underlying hash function. In addition our schemes are e cient and practical. Their performance is essentially that of the underlying hash function. Moreover they use the hash function (or its compression function) as a black box, so that widely available library code or hardware can be used to implement them in a simple way, and replaceability of the underlying hash function is easily supported.
The order of encryption and authentication for protecting communications (or: how Secure is SSL?)
, 2001
"... We study the question of how to generically compose symmetric encryption and authentication when building “secure channels” for the protection of communications over insecure networks. We show that any secure channels protocol designed to work with any combination of secure encryption (against chose ..."
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Cited by 124 (5 self)
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We study the question of how to generically compose symmetric encryption and authentication when building “secure channels” for the protection of communications over insecure networks. We show that any secure channels protocol designed to work with any combination of secure encryption (against chosen plaintext attacks) and secure MAC must use the encryptthenauthenticate method. We demonstrate this by showing that the other common methods of composing encryption and authentication, including the authenticatethenencrypt method used in SSL, are not generically secure. We show an example of an encryption function that provides (Shannon’s) perfect secrecy but when combined with any MAC function under the authenticatethenencrypt method yields a totally insecure protocol (for example, finding passwords or credit card numbers transmitted under the protection of such protocol becomes an easy task for an active attacker). The same applies to the encryptandauthenticate method used in SSH. On the positive side we show that the authenticatethenencrypt method is secure if the encryption method in use is either CBC mode (with an underlying secure block cipher) or a stream cipher (that xor the data with a random or pseudorandom pad). Thus, while we show the generic security of SSL to be broken, the current practical implementations of the protocol that use the above modes of encryption are safe.
UMAC: Fast and Secure Message Authentication
, 1999
"... Abstract. We describe a message authentication algorithm, UMAC, which can authenticate messages (in software, on contemporary machines) roughly an order of magnitude faster than current practice (e.g., HMACSHA1), and about twice as fast as times previously reported for the universal hashfunction f ..."
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Cited by 112 (14 self)
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Abstract. We describe a message authentication algorithm, UMAC, which can authenticate messages (in software, on contemporary machines) roughly an order of magnitude faster than current practice (e.g., HMACSHA1), and about twice as fast as times previously reported for the universal hashfunction family MMH. To achieve such speeds, UMAC uses a new universal hashfunction family, NH, and a design which allows effective exploitation of SIMD parallelism. The “cryptographic ” work of UMAC is done using standard primitives of the user’s choice, such as a block cipher or cryptographic hash function; no new heuristic primitives are developed here. Instead, the security of UMAC is rigorously proven, in the sense of giving exact and quantitatively strong results which demonstrate an inability to forge UMACauthenticated messages assuming an inability to break the underlying cryptographic primitive. Unlike conventional, inherently serial MACs, UMAC is parallelizable, and will have everfaster implementation speeds as machines offer up increasing amounts of parallelism. We envision UMAC as a practical algorithm for nextgeneration message authentication. 1
HAIL: A HighAvailability and Integrity Layer for Cloud Storage
, 2009
"... We introduce HAIL (HighAvailability and Integrity Layer), a distributed cryptographic system that permits a set of servers to prove to a client that a stored file is intact and retrievable. HAIL strengthens, formally unifies, and streamlines distinct approaches from the cryptographic and distribute ..."
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Cited by 80 (1 self)
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We introduce HAIL (HighAvailability and Integrity Layer), a distributed cryptographic system that permits a set of servers to prove to a client that a stored file is intact and retrievable. HAIL strengthens, formally unifies, and streamlines distinct approaches from the cryptographic and distributedsystems communities. Proofs in HAIL are efficiently computable by servers and highly compact— typically tens or hundreds of bytes, irrespective of file size. HAIL cryptographically verifies and reactively reallocates file shares. It is robust against an active, mobile adversary, i.e., one that may progressively corrupt the full set of servers. We propose a strong, formal adversarial model for HAIL, and rigorous analysis and parameter choices. We show how HAIL improves on the security and efficiency of existing tools, like Proofs of Retrievability (PORs) deployed on individual servers. We also report on a prototype implementation. 1
Authenticated MultiParty Key Agreement
, 1996
"... We examine multiparty key agreement protocols that provide (i) key authentication, (ii) key confirmation and (iii) forward secrecy. Several minor (repairable) attacks are presented against previous twoparty key agreement schemes and a model for key agreement is presented that provably provides the ..."
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Cited by 70 (2 self)
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We examine multiparty key agreement protocols that provide (i) key authentication, (ii) key confirmation and (iii) forward secrecy. Several minor (repairable) attacks are presented against previous twoparty key agreement schemes and a model for key agreement is presented that provably provides the properties listed above. A generalization of the BurmesterDesmedt model (Eurocrypt '94) for multiparty key agreement is given, allowing a transformation of any twoparty key agreement scheme into a multiparty scheme. Multiparty schemes (based on the general model and two specific 2party schemes) are presented that reduce the number of rounds required for key computation compared to the specific BurmesterDesmedt scheme. It is also shown how the specific BurmesterDesmedt scheme fails to provide key authentication. 1991 AMS Classification: 94A60 CR Categories: D.4.6 Key Words: multiparty, key agreement, key authentication, key confirmation, forward secrecy. Carleton University, Sc...
On Fast and Provably Secure Message Authentication Based on Universal Hashing
 In Advances in Cryptology – CRYPTO ’96
, 1996
"... There are wellknown techniques for message authentication using universal hash functions. This approach seems very promising, as it provides schemes that are both efficient and provably secure under reasonable assumptions. This paper contributes to this line of research in two ways. First, it analy ..."
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Cited by 67 (0 self)
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There are wellknown techniques for message authentication using universal hash functions. This approach seems very promising, as it provides schemes that are both efficient and provably secure under reasonable assumptions. This paper contributes to this line of research in two ways. First, it analyzes the basic construction and some variants under more realistic and practical assumptions. Second, it shows how these schemes can be efficiently implemented, and it reports on the results of empirical performance tests that demonstrate that these schemes are competitive with other commonly employed schemes whose security is less wellestablished. 1 Introduction Message Authentication. Message authentication schemes are an important security tool. As more and more data is being transmitted over networks, the need for secure, highspeed, softwarebased message authentication is becoming more acute. The setting for message authentication is the following. Two parties A and B agree on a secre...
Performance analysis of MD5
 Computer Science of the University of Bologna, Italy. From
, 1995
"... MD5 is an authentication algorithm proposed as the required implementation of the authentication option in IPv6. This paper presents an analysis of the speed at which MD5 can be implemented in software and hardware, and discusses whether its use interferes with high bandwidth networking. The analysi ..."
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Cited by 51 (1 self)
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MD5 is an authentication algorithm proposed as the required implementation of the authentication option in IPv6. This paper presents an analysis of the speed at which MD5 can be implemented in software and hardware, and discusses whether its use interferes with high bandwidth networking. The analysis indicates that MD5 software currently runs at 85 Mbps on a 190 Mhz RISC architecture, a rate that cannot be improved more than 2040%. Because MD5 processes the entire body of a packet, this data rate is insufficient for current high bandwidth networks, including HiPPI and FiberChannel. Further analysis indicates that a 300 Mhz custom VLSI CMOS hardware implementation of MD5 may run as fast as 256 Mbps. The hardware rate cannot support existing IPv4 data rates on high bandwidth links (800 Mbps HiPPI). The use of MD5 as the default required authentication algorithm in IPv6 should therefore be reconsidered, and an alternative should be proposed. This paper includes a brief description of the properties of such an alternative, including a sample alternate hash algorithm.
CBC MAC for RealTime Data Sources
 JOURNAL OF CRYPTOLOGY
, 1997
"... The Cipher Block Chaining (CBC) Message Authentication Code (MAC) is an authentication method which is widely used in practice. It is well known that the naive use of CBC MAC for variable length messages is not secure, and a few rules of thumb for the correct use of CBC MAC are known by folklore. ..."
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Cited by 44 (0 self)
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The Cipher Block Chaining (CBC) Message Authentication Code (MAC) is an authentication method which is widely used in practice. It is well known that the naive use of CBC MAC for variable length messages is not secure, and a few rules of thumb for the correct use of CBC MAC are known by folklore. The first rigorous proof of the security of CBC MAC, when used on fixed length messages, was given only recently by Bellare, Kilian and Rogaway [3]. They also suggested variants of CBC MAC that handle variable length messages but in these variants the length of the message has to be known in advance (i.e., before the message is processed). We study CBC authentication of real time applications in which the length of the message is not known until the message ends, and furthermore, since the application is realtime, it is not possible to start processing the authentication only after the message ends. We first present a variant of CBC MAC, called double MAC (DMAC) which handles messages of variable unknown lengths. Computing DMAC on a message is virtually as simple and as efficient as computing the standard CBC MAC on the message. We provide a rigorous proof that its security is implied by the security of the underlying block cipher. Next, we argue that the basic CBC MAC is secure when applied to prefix free message space. A message space can be made prefix free by authenticating also the (usually hidden) last character which marks the end of the message.
FloatingPoint Arithmetic And Message Authentication
, 2000
"... There is a wellknown class of message authentication systems guaranteeing that attackers will have a negligible chance of successfully forging a message. This paper shows how one of these systems can hash messages at extremely high speed  much more quickly than previous systems at the same securi ..."
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Cited by 28 (8 self)
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There is a wellknown class of message authentication systems guaranteeing that attackers will have a negligible chance of successfully forging a message. This paper shows how one of these systems can hash messages at extremely high speed  much more quickly than previous systems at the same security level  using IEEE floatingpoint arithmetic. This paper also presents a survey of the literature in a unified mathematical framework.
On the security of two MAC algorithms
 In Advances in Cryptology — EUROCRYPT ’96
, 1996
"... We consider the security of two message authentication code �MAC � algorithms� the MD5�based envelope method �RFC 1828� � and the banking standard MAA �ISO 8731�2�. Customization of a general MAC forgery attack allows improvements in both cases. For the envelope method � the forgery attack is extend ..."
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Cited by 28 (4 self)
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We consider the security of two message authentication code �MAC � algorithms� the MD5�based envelope method �RFC 1828� � and the banking standard MAA �ISO 8731�2�. Customization of a general MAC forgery attack allows improvements in both cases. For the envelope method � the forgery attack is extended to allow key recovery� for example � a 128�bit key can be recovered using 2 67 known text�MAC pairs and time plus 2 13 chosen texts. For MAA � internal collisions are found with fewer and shorter messages than previously by exploiting the algorithm�s internal structure � the number of chosen texts �each 256 Kbyte long � for a forgery can be reduced by two orders of magnitude � e.g. from 2 24 to 2 17. Moreover � certain internal collisions allow key recovery � and weak keys for MAA are identi�ed. 1