# Tag Info

## New answers tagged ssh

0

Parallelization is not a necessity but it can help to speed things up if you have a multicore processor. This is because of the parallel nature of CTR mode where the blocks are encrypted independently of each other. Another main advantage, besides being parallelizable, is that unlike CBC, CTR mode can perform certain calculations offline to prepare the key ...

3

Other advantages of CTR are: easier to decrypt from a certain offset within the ciphertext no randomness requirements for the nonce nonce can be calculated, e.g. be a simple counter nonce can be a message identifier $E = D$: encryption is the same as decryption, which means only encryption or decryption required from the block cipher less logic ...

3

There seems to be an attack on SSH when using CBC: Plaintext Recovery Attacks Against SSH. I have just scanned the paper and they state, that this will not be possible when CTR mode is used. I don't think that en-/decryption parallelization is need or even utilized in SSH. Update: Link to CERT concerning the topic: Vulnerability Note VU#958563 SSH CBC ...

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