New answers tagged format-preserving
In the decrypting steps use AES_encrypt itself instead of AES_decrypt, AES decrypt is never needed. Remember while encrypting, AES_encrypt is only used as a Pseudo Random Function, we don't really need AES_decrypt method even in decrypting phase. This might seem little confusing at first but not needed. Please check the proof given for this answer
DISCLAIMER: any implementation of the following should be reviewed and analyzed before being used in a non-test environment. I have tested an implementation that operates as expected for 32 and 64-bit inputs, but proper round counts have not been determined. Most modern block ciphers already use building blocks that operate on 32-bit integers as they are ...
We have designed FNR encryption scheme for this very purpose of preserving lengths and formats of small input fields ( $ 32 <= x < 128$ bits). It uses Naor and Reingold's PWIP extensions to classic fiestel networks. They have proved it to be more secure than classic Feistels. We have made it practical by using invertible matrices rather than working in ...
I'm not aware of any implementations, but I'm also not aware of any patents on this algorithm. Furthermore, that algorithm can quite directly be made tweakable, as that paper describes on pages 10-13.
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