Artin's braid groups currently provide a promising background for cryptographical applications, s... more Artin's braid groups currently provide a promising background for cryptographical applications, since the first cryptosystems using braids were introduced in [2, 3, 18] (see also [22]). A variety of key agreement protocols based on braids have been described, but few authentication or signature schemes have been proposed so far. We introduce three authentication schemes based on braids, two of them being zero-knowledge interactive proofs of knowledge. Then we discuss their possible implementations, involving normal forms or an alternative braid algorithm, called handle reduction, which can achieve good efficiency under specific requirements.
In 2008, Groth and Sahai proposed a general methodology for constructing non-interactive zero-kno... more In 2008, Groth and Sahai proposed a general methodology for constructing non-interactive zero-knowledge (and witness-indistinguishable) proofs in bilinear groups. While avoiding expensive NP-reductions, these proof systems are still inefficient due to the number of pairing computations required for verification. We apply recent techniques of batch verification to the Groth-Sahai proof systems and succeed to improve significantly the complexity of proof verification. We give explicit batch-verification formulas for generic Groth-Sahai equations (whose cost is less than a tenth of the original) as well as for specific popular protocols relying on their methodology (namely Groth's group signatures and the P-signatures by Belenkiy, Chase, Kohlweiss and Lysyanskaya).
In this paper, we present Decim v2 , a stream cipher hardwareoriented selected for the phase 3 of... more In this paper, we present Decim v2 , a stream cipher hardwareoriented selected for the phase 3 of the ECRYPT stream cipher project eSTREAM. As required by the initial call for hardware-oriented stream cipher contribution, Decim v2 manages 80-bit secret keys and 64-bit public initialization vectors. The design of Decim v2 combines two filtering mechanisms: a nonlinear Boolean filter over a LFSR, followed by an irregular decimation mechanism called the ABSG. Since designers have been invited to demonstrate flexibility of their design by proposing variants that take 128-bit keys, we also present a 128-bit security version of Decim called Decim-128.
Method of Processing Data Streams Received by a Wireless Communication Apparatus and at Least Partly Requiring Cryptographic Processing Operations and Corresponding Apparatus
Artin's braid groups currently provide a promising background for cryptographical applications, s... more Artin's braid groups currently provide a promising background for cryptographical applications, since the first cryptosystems using braids were introduced in [2, 3, 18] (see also [22]). A variety of key agreement protocols based on braids have been described, but few authentication or signature schemes have been proposed so far. We introduce three authentication schemes based on braids, two of them being zero-knowledge interactive proofs of knowledge. Then we discuss their possible implementations, involving normal forms or an alternative braid algorithm, called handle reduction, which can achieve good efficiency under specific requirements.
In 2008, Groth and Sahai proposed a general methodology for constructing non-interactive zero-kno... more In 2008, Groth and Sahai proposed a general methodology for constructing non-interactive zero-knowledge (and witness-indistinguishable) proofs in bilinear groups. While avoiding expensive NP-reductions, these proof systems are still inefficient due to the number of pairing computations required for verification. We apply recent techniques of batch verification to the Groth-Sahai proof systems and succeed to improve significantly the complexity of proof verification. We give explicit batch-verification formulas for generic Groth-Sahai equations (whose cost is less than a tenth of the original) as well as for specific popular protocols relying on their methodology (namely Groth's group signatures and the P-signatures by Belenkiy, Chase, Kohlweiss and Lysyanskaya).
In this paper, we present Decim v2 , a stream cipher hardwareoriented selected for the phase 3 of... more In this paper, we present Decim v2 , a stream cipher hardwareoriented selected for the phase 3 of the ECRYPT stream cipher project eSTREAM. As required by the initial call for hardware-oriented stream cipher contribution, Decim v2 manages 80-bit secret keys and 64-bit public initialization vectors. The design of Decim v2 combines two filtering mechanisms: a nonlinear Boolean filter over a LFSR, followed by an irregular decimation mechanism called the ABSG. Since designers have been invited to demonstrate flexibility of their design by proposing variants that take 128-bit keys, we also present a 128-bit security version of Decim called Decim-128.
Method of Processing Data Streams Received by a Wireless Communication Apparatus and at Least Partly Requiring Cryptographic Processing Operations and Corresponding Apparatus
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