TY - GEN

T1 - A domain extender for the ideal cipher

AU - Coron, Jean Sébastien

AU - Dodis, Yevgeniy

AU - Mandal, Avradip

AU - Seurin, Yannick

PY - 2010

Y1 - 2010

N2 - We describe the first domain extender for ideal ciphers, i.e. we show a construction that is indifferentiable from a 2n-bit ideal cipher, given a n-bit ideal cipher. Our construction is based on a 3-round Feistel, and is more efficient than first building a n-bit random oracle from a n-bit ideal cipher (as in [9]) and then a 2n-bit ideal cipher from a n-bit random oracle (as in [10], using a 6-round Feistel). We also show that 2 rounds are not enough for indifferentiability by exhibiting a simple attack. We also consider our construction in the standard model: we show that 2 rounds are enough to get a 2n-bit tweakable block-cipher from a n-bit tweakable block-cipher and we show that with 3 rounds we can get beyond the birthday security bound.

AB - We describe the first domain extender for ideal ciphers, i.e. we show a construction that is indifferentiable from a 2n-bit ideal cipher, given a n-bit ideal cipher. Our construction is based on a 3-round Feistel, and is more efficient than first building a n-bit random oracle from a n-bit ideal cipher (as in [9]) and then a 2n-bit ideal cipher from a n-bit random oracle (as in [10], using a 6-round Feistel). We also show that 2 rounds are not enough for indifferentiability by exhibiting a simple attack. We also consider our construction in the standard model: we show that 2 rounds are enough to get a 2n-bit tweakable block-cipher from a n-bit tweakable block-cipher and we show that with 3 rounds we can get beyond the birthday security bound.

KW - Ideal cipher model

KW - Indifferentiability

KW - Tweakable block-cipher

UR - http://www.scopus.com/inward/record.url?scp=77949598897&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=77949598897&partnerID=8YFLogxK

U2 - 10.1007/978-3-642-11799-2_17

DO - 10.1007/978-3-642-11799-2_17

M3 - Conference contribution

AN - SCOPUS:77949598897

SN - 3642117988

SN - 9783642117985

T3 - Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)

SP - 273

EP - 289

BT - Theory of Cryptography - 7th Theory of Cryptography Conference, TCC 2010, Proceedings

T2 - 7th Theory of Cryptography Conference, TCC 2010

Y2 - 9 February 2010 through 11 February 2010

ER -