Dodis, Yevgeniy; Pietrzak, Krzysztof ZIST Austria ; Puniya, Prashant
We propose a new mode of operation, enciphered CBC, for domain extension of length-preserving functions (like block ciphers), which is a variation on the popular CBC mode of operation. Our new mode is twice slower than CBC, but has many (property-preserving) properties not enjoyed by CBC and other known modes. Most notably, it yields the first constant-rate Variable Input Length (VIL) MAC from any length preserving Fixed Input Length (FIL) MAC. This answers the question of Dodis and Puniya from Eurocrypt 2007. Further, our mode is a secure domain extender for PRFs (with basically the same security as encrypted CBC). This provides a hedge against the security of the block cipher: if the block cipher is pseudorandom, one gets a VIL-PRF, while if it is "only" unpredictable, one "at least" gets a VIL-MAC. Additionally, our mode yields a VIL random oracle (and, hence, a collision-resistant hash function) when instantiated with length-preserving random functions, or even random permutations (which can be queried from both sides). This means that one does not have to re-key the block cipher during the computation, which was critically used in most previous constructions (analyzed in the ideal cipher model).
198 - 219
EUROCRYPT: Theory and Applications of Cryptographic Techniques
Dodis Y, Pietrzak KZ, Puniya P. A new mode of operation for block ciphers and length preserving MACs. In: Vol 4965. Springer; 2008:198-219. doi:10.1007/978-3-540-78967-3_12
Dodis, Y., Pietrzak, K. Z., & Puniya, P. (2008). A new mode of operation for block ciphers and length preserving MACs (Vol. 4965, pp. 198–219). Presented at the EUROCRYPT: Theory and Applications of Cryptographic Techniques, Springer. https://doi.org/10.1007/978-3-540-78967-3_12
Dodis, Yevgeniy, Krzysztof Z Pietrzak, and Prashant Puniya. “A New Mode of Operation for Block Ciphers and Length Preserving MACs,” 4965:198–219. Springer, 2008. https://doi.org/10.1007/978-3-540-78967-3_12.
Y. Dodis, K. Z. Pietrzak, and P. Puniya, “A new mode of operation for block ciphers and length preserving MACs,” presented at the EUROCRYPT: Theory and Applications of Cryptographic Techniques, 2008, vol. 4965, pp. 198–219.
Dodis Y, Pietrzak KZ, Puniya P. 2008. A new mode of operation for block ciphers and length preserving MACs. EUROCRYPT: Theory and Applications of Cryptographic Techniques, LNCS, vol. 4965, 198–219.
Dodis, Yevgeniy, et al. A New Mode of Operation for Block Ciphers and Length Preserving MACs. Vol. 4965, Springer, 2008, pp. 198–219, doi:10.1007/978-3-540-78967-3_12.