Topic
Cipher
About: Cipher is a research topic. Over the lifetime, 9409 publications have been published within this topic receiving 110309 citations. The topic is also known as: cypher & cryptographic algorithm.
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18 Sep 2009
TL;DR: The preferred embodiment of the method of the present invention comprises steps of generating and receiving messages at an Internet e-mail system, encrypting said messages, updating a cipher dictionary at a cipher proxy, and decoding and decrypting the messages when accessed by a user as discussed by the authors.
Abstract: The preferred embodiments of the present invention disclose a security transformation system which includes an e-mail client, a cipher proxy, a dictionary database and an Internet e-mail system. The system is capable of generating and receiving messages and performing a cipher substitution and encryption of key fields of messages when they are stored at a user's Internet e-mail system. When the messages are received or accessed the system permits deciphering and decrypting the message using a reverse security transformation The preferred embodiments of the method of the present invention comprises steps of generating and receiving messages at an Internet e-mail system, performing a security transformation on said messages, encrypting said messages, updating a cipher dictionary at a cipher proxy, and decoding and decrypting the messages when accessed by a user.
108 citations
TL;DR: An efficient visually meaningful double color image encryption algorithm is proposed by combining 2D compressive sensing (CS) with an embedding technique to achieve simultaneous compression and encryption.
108 citations
18 Nov 2002
TL;DR: It is shown that some common obfuscation methods can be defeated using a fault injection attack, namely an attack where during program execution an attacker injects errors into the program environment.
Abstract: We study the strength of certain obfuscation techniques used to protect software from reverse engineering and tampering. We show that some common obfuscation methods can be defeated using a fault injection attack, namely an attack where during program execution an attacker injects errors into the program environment. By observing how the program fails under certain errors the attacker can deduce the obfuscated information in the program code without having to unravel the obfuscation mechanism. We apply this technique to extract a secret key from a block cipher obfuscated using a commercial obfuscation tool and draw conclusions on preventing this weakness.
107 citations
TL;DR: This work presents a thorough investigation of HEVC-CABAC from an encryption standpoint, and an algorithm is devised for conversion of non-dyadic ES to dyadic, which can be concatenated to form plaintext for AES-CFB.
Abstract: This paper presents one of the first methods allowing the protection of the newly emerging video codec HEVC (High Efficiency Video Coding). Visual protection is achieved through selective encryption (SE) of HEVC-CABAC binstrings in a format compliant manner. The SE approach developed for HEVC is different from that of H.264/AVC in several aspects. Truncated rice code is introduced for binarization of quantized transform coefficients (QTCs) instead of truncated unary code. The encryption space (ES) of binstrings of truncated rice codes is not always dyadic and cannot be represented by an integer number of bits. Hence they cannot be concatenated together to create plaintext for the CFB (Cipher Feedback) mode of AES, which is a self-synchronizing stream cipher for so-called AES-CFB. Another challenge for SE in HEVC concerns the introduction of context, which is adaptive to QTC. This work presents a thorough investigation of HEVC-CABAC from an encryption standpoint. An algorithm is devised for conversion of non-dyadic ES to dyadic, which can be concatenated to form plaintext for AES-CFB. For selectively encrypted binstrings, the context of truncated rice code for binarization of future syntax elements is guaranteed to remain unchanged. Hence the encrypted bitstream is format-compliant and has exactly the same bit-rate. The proposed technique requires very little processing power and is ideal for playback on hand held devices. The proposed scheme is acceptable for DRM of a wide range of applications, since it protects the contour and motion information, along with texture. Several benchmark video sequences of different resolutions and diverse contents were used for experimental evaluation of the proposed algorithm. A detailed security analysis of the proposed scheme verified the validity of the proposed encryption scheme for content protection in a wide range of applications.
107 citations
16 Aug 1998
TL;DR: Asymptotically optimal strategies for both encryption and guessing are demonstrated, which are universal in the sense of being independent of the statistics of the source.
Abstract: The Shannon theory of cipher systems is combined with recent work on guessing values of random variables. The security of encryption systems is measured in terms of moments of the number of guesses needed for the wiretapper to uncover the plaintext given the cryptogram. While the encrypter aims at maximizing the guessing effort, the wiretapper strives to minimize it, e.g., by ordering guesses according to descending order of posterior probabilities of plaintexts given the cryptogram. For a memoryless plaintext source and a given key rate, a single-letter characterization is given for the highest achievable guessing exponent function, that is, the exponential rate of the pth moment of the number of guesses as a function of the plaintext message length. Moreover, we demonstrate asymptotically optimal strategies for both encryption and guessing, which are universal in the sense of being independent of the statistics of the source. The guessing exponent is then investigated as a function of the key rate and related to the large-deviations guessing performance.
107 citations