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- ### Supported Ciphers
- | Name | Block Size (bytes) | Key Range (bytes) | Rounds |
- |---|---|---|---|
- | #Crypto.BlowfishCipher | 8 | 8 ... 56 | 16 |
- | #Crypto.TeaCipher | 8 | 16 | 32 |
- | #Crypto.XteaCipher | 8 | 16 | 32 |
- | #Crypto.AESCipher | 16 | 16, 24, 32 | 10, 12, 14 |
- | #Crypto.TwofishCipher | 16 | 16, 24, 32 | 16 |
- | #Crypto.DESCipher | 8 | 8 | 16 |
- | 3DES (EDE mode) (See #Crypto.DESCipher) | 8 | 16, 24 | 16 |
- | #Crypto.Cast5Cipher | 8 | 5 ... 16 | 12, 16 |
- | #Crypto.NoekeonCipher | 16 | 16 | 16 |
- | #Crypto.SkipjackCipher | 8 | 10 | 32 |
- | #Crypto.AnubisCipher | 16 | 16 ... 40 | 12 ... 18 |
- | #Crypto.KhazadCipher | 8 | 16 | 8 |
- | #Crypto.KSEEDCipher | 16 | 16 | 16 |
- | #Crypto.KASUMICipher | 8 | 16 | 8 |
- | #Crypto.CamelliaCipher | 16 | 16, 24, 32 | 18, 24 |
- | #Crypto.IDEACipher | 8 | 16 | 8 |
- | #Crypto.SerpentCipher | 16 | 16, 24, 32 | 32 |
- ### Key sizes and Number of Rounds
- As a general rule of thumb, do not use symmetric keys under 80 bits if you can help it.
- Only a few of the ciphers support smaller keys (mainly for test vectors anyways).
- Ideally, your application should be making at least 256 bit keys. This is not because you are to be paranoid.
- It is because if your PRNG has a bias of any sort the more bits the better.
- For example, if you have `Pr[X = 1] = 1/2 ±γ` where `|γ| > 0` then the total amount of entropy in N bits is `N·−log^2 (1/2 +|γ|)`.
- So if `γ` were 0.25 (a severe bias) a 256-bit string would have about 106 bits of entropy whereas a 128-bit string would have only 53 bits of entropy.
- The number of rounds of most ciphers is not an option you can change. Only RC5 allows you to change the number of rounds.
- By passing zero as the number of rounds all ciphers will use their default number of rounds. Generally the ciphers are configured such that the default
- number of rounds provide adequate security for the given block and key size.
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