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In cryptography, a cipher block chaining message authentication code (CBC-MAC) is a technique for constructing a message authentication code (MAC) from a block cipher.The message is encrypted with some block cipher algorithm in cipher block chaining (CBC) mode to create a chain of blocks such that each block depends on the proper encryption of the previous block.
As the name suggests, CCM mode combines counter (CTR) mode for confidentiality with cipher block chaining message authentication code (CBC-MAC) for authentication. These two primitives are applied in an "authenticate-then-encrypt" manner: CBC-MAC is first computed on the message to obtain a message authentication code (MAC), then the message and the MAC are encrypted using counter mode.
Counter with cipher block chaining message authentication code (counter with CBC-MAC; CCM) is an authenticated encryption algorithm designed to provide both authentication and confidentiality. CCM mode is only defined for block ciphers with a block length of 128 bits. [14] [15]
The 2011 BEAST attack exploited the non-random chained IV and broke all CBC algorithms in TLS 1.0 and under. [29] In addition, deeper analysis of SSL/TLS modeled the protection as MAC-then-pad-then-encrypt, i.e. the plaintext is first padded to the block size of the encryption function.
The message and the MAC tag are then sent to the receiver. The receiver in turn runs the message portion of the transmission through the same MAC algorithm using the same key, producing a second MAC data tag. The receiver then compares the first MAC tag received in the transmission to the second generated MAC tag.
[4] [6] Additionally the attack requires the use of either ChaCha20-Poly1305 or a CBC cipher in combination with Encrypt-then-MAC modes of encryption. [7] The SSH developers have stated that the major impact of the attack is the capability to degrade the keystroke timing obfuscation features of SSH. [6]
A man who was running away from police has been arrested after getting stuck in a chimney while trying to hide from them, authorities said. The incident occurred on Tuesday evening in Fall River ...
One-key MAC (OMAC) is a family of message authentication codes constructed from a block cipher much like the CBC-MAC algorithm. It may be used to provide assurance of the authenticity and, hence, the integrity of data. Two versions are defined: The original OMAC of February 2003, which is seldom used. [1] The preferred name is now "OMAC2". [2]