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CodeBased GamePlaying Proofs and the Security of Triple Encryption
 Eurocrypt 2006, LNCS
"... (Draft 3.0) The gameplaying technique is a powerful tool for analyzing cryptographic constructions. We illustrate this by using games as the central tool for proving security of threekey tripleencryption, a longstanding open problem. Our result, which is in the idealcipher model, demonstrates t ..."
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Cited by 46 (10 self)
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(Draft 3.0) The gameplaying technique is a powerful tool for analyzing cryptographic constructions. We illustrate this by using games as the central tool for proving security of threekey tripleencryption, a longstanding open problem. Our result, which is in the idealcipher model, demonstrates that for DES parameters (56bit keys and 64bit plaintexts) an adversary’s maximal advantage is small until it asks about 278 queries. Beyond this application, we develop the foundations for game playing, formalizing a general framework for gameplaying proofs and discussing techniques used within such proofs. To further exercise the gameplaying framework we show how to use games to get simple proofs for the PRP/PRF Switching Lemma, the security
OMAC: OneKey CBC MAC
 Preproceedings of Fast Software Encryption, FSE 2003
, 2002
"... In this paper, we present Onekey CBC MAC (OMAC) and prove its security for arbitrary length messages. OMAC takes only one key, K (k bits) of a block cipher E. Previously, XCBC requires three keys, (k + 2n) bits in total, and TMAC requires two keys, (k + n) bits in total, where n denotes the block l ..."
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Cited by 27 (6 self)
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In this paper, we present Onekey CBC MAC (OMAC) and prove its security for arbitrary length messages. OMAC takes only one key, K (k bits) of a block cipher E. Previously, XCBC requires three keys, (k + 2n) bits in total, and TMAC requires two keys, (k + n) bits in total, where n denotes the block length of E.
Improved security analyses for CBC MACs
 In Advances in Cryptology Crypto 2005, LNCS 3621
, 2005
"... Abstract We present an improved bound on the advantage of any qquery adversary at distinguishingbetween the CBC MAC over a random nbit permutation and a random function outputting nbits. The result assumes that no message queried is a prefix of any other, as is the case when all messages to be MAC ..."
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Cited by 24 (6 self)
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Abstract We present an improved bound on the advantage of any qquery adversary at distinguishingbetween the CBC MAC over a random nbit permutation and a random function outputting nbits. The result assumes that no message queried is a prefix of any other, as is the case when all messages to be MACed have the same length. We go on to give an improved analysis ofthe encrypted CBC MAC, where there is no restriction on queried messages. Letting
Security Flaws Induced by CBC Padding  Applications to SSL, IPSEC, WTLS
 Proceedings of In Advances in Cryptology  EUROCRYPT'02
, 2002
"... are first preformatted, then encrypted in CBC mode with a block cipher. Decryption needs to check if the format is valid. Validity of the format is easily leaked from communication protocols in a chosen ciphertext attack since the receiver usually sends an acknowledgment or an error message. This i ..."
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Cited by 11 (1 self)
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are first preformatted, then encrypted in CBC mode with a block cipher. Decryption needs to check if the format is valid. Validity of the format is easily leaked from communication protocols in a chosen ciphertext attack since the receiver usually sends an acknowledgment or an error message. This is a side channel. In this paper we show various ways to perform an efficient side channel attack. We discuss potential applications, extensions to other padding schemes and various ways to fix the problem. 1
PseudoRandom Functions and Parallelizable Modes of Operations of a Block Cipher
"... Abstract. This paper considers the construction and analysis of pseudorandom functions (PRFs) with specific reference to modes of operations of a block cipher. In the context of message authentication codes (MACs), earlier independent work by Bernstein and Vaudenay show how to reduce the analysis o ..."
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Cited by 9 (4 self)
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Abstract. This paper considers the construction and analysis of pseudorandom functions (PRFs) with specific reference to modes of operations of a block cipher. In the context of message authentication codes (MACs), earlier independent work by Bernstein and Vaudenay show how to reduce the analysis of relevant PRFs to some probability calculations. In the first part of the paper, we revisit this result and use it to prove a general result on constructions which use a PRF with a “small ” domain to build a PRF with a “large ” domain. This result is used to analyse two new parallelizable PRFs which are suitable for use as MAC schemes. The first scheme, called iPMAC, is based on a block cipher and improves upon the wellknown PMAC algorithm. The improvements consist in faster masking operations and the removal of a design stage discrete logarithm computation. The second scheme, called VPMAC, uses a keyed compression function rather than a block cipher. The only previously known compression function based parallelizable PRF is called the protected counter sum (PCS) and is due to Bernstein. VPMAC improves upon PCS by requiring lesser number of calls to the compression function. The second part of the paper takes a new look at the construction and analysis of modes of operations for authenticated encryption (AE) and for authenticated encryption with associated data (AEAD). Usually, the most complicated part in the security analysis of such modes is the analysis of authentication
The GamePlaying Technique
, 2004
"... In the gameplaying technique, one writes a pseudocode game such that an adversary's advantage in attacking some cryptographic construction is bounded above by the probability that the game sets a flag bad. This probability is then upper bounded by making stepwise, syntactical refinements to th ..."
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Cited by 5 (0 self)
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In the gameplaying technique, one writes a pseudocode game such that an adversary's advantage in attacking some cryptographic construction is bounded above by the probability that the game sets a flag bad. This probability is then upper bounded by making stepwise, syntactical refinements to the pseudocode  a chain of games. The approach was first used by Kilian and Rogaway (1996) and has been used repeatedly since, but it has never received a systematic treatment. In this paper we provide one. We develop the foundations...
Equivalence between MAC and PRF for Blockcipher based Constructions
"... Abstract. In FSE 2010, Nandi proved a sufficient condition of pseudo random function (PRF) for affine domain extensions (ADE), wide class of block cipher based domain extensions. This sufficient condition is satisfied by all known blockcipher based ADE constructions, however, it is not a characteriz ..."
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Abstract. In FSE 2010, Nandi proved a sufficient condition of pseudo random function (PRF) for affine domain extensions (ADE), wide class of block cipher based domain extensions. This sufficient condition is satisfied by all known blockcipher based ADE constructions, however, it is not a characterization of PRF. In this paper we completely characterize the ADE and show that message authentication code (MAC) and weakly collision resistant (WCR) are indeed equivalent to PRF. Note that a PRF is trivially a MAC and WCR, however, the converse need not be true in general. So our result suggests that it would be sufficient to ensure resisting against weakly collision attack or the forging attack to construct a pseudo random function ADE. Unlike FSE 2010 paper, here we consider the forced collisions of inputs of underlying blockciphers by incorporating the final outputs of a domain extension queried by an adaptive adversary. This is the main reason why we are able to obtain a characterization of PRF. Our approach is a more general and hence might have other theoretical interest.