- tag: § Cryptography
- Because of symmetry of Xor, the decryption algorithm is exactly the same as encryption.
- Encrypt IV and use that as IV for the next block.
- Xor encrypted IV with the block of ciphertext.
- The stream of encrypted IVs (keystream) can be computed beforehand and applied in parallel.
- The keystream can be obtained by using CBC with a constant stream of zeros as input. That is useful as it allows using hardware acceleration.
- Using OFB mode with partial blocks as feedback reduces the average cycle length by factor of or more. For this reason, support for truncated feedback was removed from the specification of OFB.