Breaking the FF3 Format Preserving Encryption
نویسندگان
چکیده
The NIST standard FF3 scheme (also known as BPS scheme) is a tweakable block cipher based on a 8-round Feistel Network. We break it with a practical attack. Our attack exploits the bad domain separation in FF3 design. The attack works with chosen plaintexts and tweaks when the message domain is small. Our FF3 attack requires O(N 11 6 ) chosen plaintexts with time complexity N, where N is domain size to the Feistel Network. Due to the bad domain separation in 8-round FF3, we reduced the FF3 attack to an attack on 4-round Feistel Networks. In our generic attack, we reconstruct the entire codebook of 4-round Feistel Network with N 3 2 ( N 2 ) 1 6 known plaintexts and time complexity N.
منابع مشابه
Breaking the FF3 Format-Preserving Encryption Standard over Small Domains
The National Institute of Standards and Technology (NIST) recently published a Format-Preserving Encryption standard accepting two Feistel structure based schemes called FF1 and FF3. Particularly, FF3 is a tweakable block cipher based on an 8-round Feistel network. In CCS ̃2016, Bellare et. al. gave an attack to break FF3 (and FF1) with time and data complexity $O(Nˆ5\log(N))$, which is much lar...
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