Acrónimos: OFB
Ver:
·
[NIST-SP800-38A:2001]
·
[FIPS-81:1980]
·
Criptografía
de clave secreta
·
http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation
Modalidad de
cifrado de flujo cuyo generador de la serie cifrante está constituido por un
cifrado de bloques seguido por un selector de bits. [Ribagorda:1997]
(N) A block cipher mode that
modifies ECB mode to operate on plaintext segments of variable length less than
or equal to the block length. [FP081] (See: block cipher, [SP38A].) [RFC4949:2007]
The output feedback (OFB)
mode makes a block cipher into a synchronous stream cipher: it generates
keystream blocks, which are then XORed with the plaintext blocks to get the
ciphertext. Just as with other stream ciphers, flipping a bit in the ciphertext
produces a flipped bit in the plaintext at the same location. This property
allows many error correcting codes to function normally even when applied
before encryption.
Because of the symmetry of
the XOR operation, encryption and decryption are exactly the same.
http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation