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Merge pull request #426 from Logan007/aesKeyLenTrgrs

adopted aes key-length trigger values
pull/427/head
Luca Deri 4 years ago
committed by GitHub
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4759a99eb4
No known key found for this signature in database GPG Key ID: 4AEE18F83AFDEB23
  1. 2
      doc/Crypto.md
  2. 7
      src/transform_aes.c

2
doc/Crypto.md

@ -40,6 +40,8 @@ AES also prepends a random value to the plaintext. Its size is adjustable by cha
Apart from n2n's plain C implementation, Intel's AES-NI is supported – again, please have a look at the [Building document](./Building.md). In case of openSSL support its `evp_*` interface gets used which also offers hardware acceleration where available (SSE, AES-NI, …). It however is slower than the following stream ciphers because the CBC mode cannot compete with the optimized stream ciphers. Apart from n2n's plain C implementation, Intel's AES-NI is supported – again, please have a look at the [Building document](./Building.md). In case of openSSL support its `evp_*` interface gets used which also offers hardware acceleration where available (SSE, AES-NI, …). It however is slower than the following stream ciphers because the CBC mode cannot compete with the optimized stream ciphers.
This cipher's different key-sizes are triggered by the length of the user-provided key: 22 characters or less make n2n use AES-128, between 23 and 32 characters lead to AES-192, and 33 or more characters trigger AES-256.
### ChaCha20 ### ChaCha20
ChaCha20 was the first stream cipher supported by n2n. ChaCha20 was the first stream cipher supported by n2n.

7
src/transform_aes.c

@ -187,10 +187,11 @@ static int setup_aes_key(transop_aes_t *priv, const uint8_t *password, ssize_t p
pearson_hash_256(key_mat, password, password_len); pearson_hash_256(key_mat, password, password_len);
// the length-dependant scheme for key setup was discussed on github: // the length-dependant scheme for key setup was discussed on github:
// https://github.com/ntop/n2n/issues/101 // https://github.com/ntop/n2n/issues/101 -- as no iv encryption required
if(password_len >= 65) { // anymore, the key-size trigger values were roughly halved
if(password_len >= 33) {
key_size = AES256_KEY_BYTES; // 256 bit key_size = AES256_KEY_BYTES; // 256 bit
} else if(password_len >= 44) { } else if(password_len >= 23) {
key_size = AES192_KEY_BYTES; // 192 bit key_size = AES192_KEY_BYTES; // 192 bit
} else { } else {
key_size = AES128_KEY_BYTES; // 128 bit key_size = AES128_KEY_BYTES; // 128 bit

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