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by alcari 3584 days ago
PCI-DSS says 112 bits of security is "strong cryptography", just so people can continue using 3DES.
1 comments
CiPHPerCoder 3584 days ago
Strictly speaking, 112 bits of "security" is "strong" enough. The problem is this is usually measured as the log (base 2) of the number of possible secret keys. It ignores:

  - Block size  <- YOU ARE HERE
  - Cipher mode
  - Cipher construction and integrity checks (for non-AEAD modes)
  - Key exchange
You can break 256 bit AES if you're using 256-bit classical Diffie Hellman, for example. "But AES has 256 bits of security!" is somewhat silly to argue in such a hypothetical protocol.

This is one reason why you're better off ignoring PCI-DSS when it comes to cryptography guidelines (aside from maintaining compliance where you have obligations to remain compliant, of course).

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