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Merge pull request #426 from Logan007/aesKeyLenTrgrs

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adopted aes key-length trigger values
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Luca Deri 2020-09-18 23:49:39 +02:00 committed by GitHub
commit 4759a99eb4
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2 changed files with 6 additions and 3 deletions
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2
doc/Crypto.md
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@ -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.
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 was the first stream cipher supported by n2n.

7
src/transform_aes.c
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@ -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);
// the length-dependant scheme for key setup was discussed on github:
// https://github.com/ntop/n2n/issues/101
if(password_len >= 65) {
// https://github.com/ntop/n2n/issues/101 -- as no iv encryption required
// anymore, the key-size trigger values were roughly halved
if(password_len >= 33) {
key_size = AES256_KEY_BYTES; // 256 bit
} else if(password_len >= 44) {
} else if(password_len >= 23) {
key_size = AES192_KEY_BYTES; // 192 bit
} else {
key_size = AES128_KEY_BYTES; // 128 bit