/*
cipher.c -- Symmetric block cipher handling
- Copyright (C) 2007-2013 Guus Sliepen <guus@tinc-vpn.org>
+ Copyright (C) 2007-2017 Guus Sliepen <guus@tinc-vpn.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
return cipher_open(evp_cipher);
}
-cipher_t *cipher_open_blowfish_ofb(void) {
- return cipher_open(EVP_bf_ofb());
-}
-
void cipher_close(cipher_t *cipher) {
if(!cipher)
return;
return EVP_CIPHER_key_length(cipher->cipher) + EVP_CIPHER_iv_length(cipher->cipher);
}
+uint64_t cipher_budget(const cipher_t *cipher) {
+ /* Hopefully some failsafe way to calculate the maximum amount of bytes to
+ send/receive with a given cipher before we might run into birthday paradox
+ attacks. Because we might use different modes, the block size of the mode
+ might be 1 byte. In that case, use the IV length. Ensure the whole thing
+ is limited to what can be represented with a 64 bits integer.
+ */
+
+ if(!cipher || !cipher->cipher)
+ return UINT64_MAX; // NULL cipher
+
+ int ivlen = EVP_CIPHER_iv_length(cipher->cipher);
+ int blklen = EVP_CIPHER_block_size(cipher->cipher);
+ int len = blklen > 1 ? blklen : ivlen > 1 ? ivlen : 8;
+ int bits = len * 4 - 1;
+ return bits < 64 ? UINT64_C(1) << bits : UINT64_MAX;
+}
+
size_t cipher_blocksize(const cipher_t *cipher) {
if(!cipher || !cipher->cipher)
return 1;
int len, pad;
if(EVP_EncryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
&& EVP_EncryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
- && EVP_EncryptFinal(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
+ && EVP_EncryptFinal_ex(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
if(outlen) *outlen = len + pad;
return true;
}
int len, pad;
if(EVP_DecryptInit_ex(cipher->ctx, NULL, NULL, NULL, NULL)
&& EVP_DecryptUpdate(cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
- && EVP_DecryptFinal(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
+ && EVP_DecryptFinal_ex(cipher->ctx, (unsigned char *)outdata + len, &pad)) {
if(outlen) *outlen = len + pad;
return true;
}