6 results sorted by ID
Fast Keyed-Verification Anonymous Credentials on Standard Smart Cards
Jan Camenisch, Manu Drijvers, Petr Dzurenda, Jan Hajny
Cryptographic protocols
Cryptographic anonymous credential schemes allow users to prove their personal attributes, such as age, nationality, or the validity of a ticket or a pre-paid pass, while preserving their privacy, as such proofs are unlinkable and attributes can be selectively disclosed. Recently, Chase et al. (CCS 2014) observe that in such systems, a typical setup is that the credential issuer also serves as the verifier. They introduce keyed-verification credentials that are tailored to this setting. In...
Signer-Anonymous Designated-Verifier Redactable Signatures for Cloud-Based Data Sharing
David Derler, Stephan Krenn, Daniel Slamanig
Public-key cryptography
Redactable signature schemes allow to black out predefined parts of a signed message without affecting the validity of the signature, and are therefore an important building block in privacy-enhancing cryptography. However, a second look shows, that for many practical applications, they cannot be used in their vanilla form. On the one hand, already the identity of the signer may often reveal sensitive information to the receiver of a redacted message; on the other hand, if data leaks or is...
Practical-Time Attacks Against Reduced Variants of MISTY1
Orr Dunkelman, Nathan Keller
Secret-key cryptography
MISTY1 is a block cipher designed by Matsui in 1997. It is widely deployed in Japan where it is an e-government standard, and is recognized internationally as a NESSIE-recommended cipher as well as
an ISO standard and an RFC. Moreover, MISTY1 was selected to be the blueprint on top of which KASUMI, the GSM/3G block cipher, was based. Since its introduction, and especially in recent years, MISTY1 was subjected to extensive cryptanalytic efforts, which resulted in numerous attacks on its...
Weak Keys of the Full MISTY1 Block Cipher for Related-Key Cryptanalysis
Jiqiang Lu, Wen-She Yap, Yongzhuang Wei
Secret-key cryptography
The MISTY1 block cipher has a 64-bit block length, a 128-bit user key and a recommended number of 8 rounds. It is a Japanese CRYPTREC-recommended e-government cipher, an European NESSIE selected cipher, and an ISO international standard. Despite of considerable cryptanalytic efforts during the past fifteen years, there has been no published cryptanalytic attack on the full MISTY1 cipher algorithm. In this paper, we present related-key differential and related-key amplified boomerang attacks...
Differential Attack on Five Rounds of the SC2000 Block Cipher
Jiqiang Lu
Secret-key cryptography
The SC2000 block cipher has a 128-bit block size and a user key of 128, 192 or 256 bits, which employs a total of 6.5 rounds if a 128-bit user key is used. It is a CRYPTREC recommended e-government cipher. In this
paper we describe two 4.75-round differential characteristics with
probability $2^{-126}$ of SC2000 and seventy-six 4.75-round differential characteristics with probability $2^{-127}$. Finally,
we present a differential cryptanalysis attack on a 5-round reduced
version of SC2000 ...
Secure Online Elections in Practice
Lucie Langer, Axel Schmidt, Johannes Buchmann
Applications
Current remote e-voting schemes aim at a number of security objectives. However, this is not enough for providing secure online elections in practice. Beyond a secure e-voting protocol, there are many organizational and technical security requirements that have to be satisfied by the operational environment in which the scheme is implemented. We have investigated four state-of-the-art e-voting protocols in order to identify the organizational and technical requirements which these protocols...
Cryptographic anonymous credential schemes allow users to prove their personal attributes, such as age, nationality, or the validity of a ticket or a pre-paid pass, while preserving their privacy, as such proofs are unlinkable and attributes can be selectively disclosed. Recently, Chase et al. (CCS 2014) observe that in such systems, a typical setup is that the credential issuer also serves as the verifier. They introduce keyed-verification credentials that are tailored to this setting. In...
Redactable signature schemes allow to black out predefined parts of a signed message without affecting the validity of the signature, and are therefore an important building block in privacy-enhancing cryptography. However, a second look shows, that for many practical applications, they cannot be used in their vanilla form. On the one hand, already the identity of the signer may often reveal sensitive information to the receiver of a redacted message; on the other hand, if data leaks or is...
MISTY1 is a block cipher designed by Matsui in 1997. It is widely deployed in Japan where it is an e-government standard, and is recognized internationally as a NESSIE-recommended cipher as well as an ISO standard and an RFC. Moreover, MISTY1 was selected to be the blueprint on top of which KASUMI, the GSM/3G block cipher, was based. Since its introduction, and especially in recent years, MISTY1 was subjected to extensive cryptanalytic efforts, which resulted in numerous attacks on its...
The MISTY1 block cipher has a 64-bit block length, a 128-bit user key and a recommended number of 8 rounds. It is a Japanese CRYPTREC-recommended e-government cipher, an European NESSIE selected cipher, and an ISO international standard. Despite of considerable cryptanalytic efforts during the past fifteen years, there has been no published cryptanalytic attack on the full MISTY1 cipher algorithm. In this paper, we present related-key differential and related-key amplified boomerang attacks...
The SC2000 block cipher has a 128-bit block size and a user key of 128, 192 or 256 bits, which employs a total of 6.5 rounds if a 128-bit user key is used. It is a CRYPTREC recommended e-government cipher. In this paper we describe two 4.75-round differential characteristics with probability $2^{-126}$ of SC2000 and seventy-six 4.75-round differential characteristics with probability $2^{-127}$. Finally, we present a differential cryptanalysis attack on a 5-round reduced version of SC2000 ...
Current remote e-voting schemes aim at a number of security objectives. However, this is not enough for providing secure online elections in practice. Beyond a secure e-voting protocol, there are many organizational and technical security requirements that have to be satisfied by the operational environment in which the scheme is implemented. We have investigated four state-of-the-art e-voting protocols in order to identify the organizational and technical requirements which these protocols...
