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replaced twofish implementation by a faster version

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This commit is contained in:
Logan007 2020-08-26 20:06:40 +05:45
parent d5c1295bec
commit bf6ef081e0
2 changed files with 12 additions and 8 deletions
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4
src/tf.c
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@ -465,6 +465,7 @@ int tf_cbc_decrypt (unsigned char *out, const unsigned char *in, size_t in_len,
const unsigned char *iv, tf_context_t *ctx) {
uint8_t tmp[TF_BLOCK_SIZE];
uint8_t old[TF_BLOCK_SIZE];
size_t i;
size_t n;
@ -472,9 +473,10 @@ int tf_cbc_decrypt (unsigned char *out, const unsigned char *in, size_t in_len,
n = in_len / TF_BLOCK_SIZE;
for(i=0; i < n; i++) {
memcpy(old, &in[i * TF_BLOCK_SIZE], TF_BLOCK_SIZE);
twofish_internal_decrypt(ctx->K, ctx->QF, &out[i * TF_BLOCK_SIZE], &in[i * TF_BLOCK_SIZE]);
fix_xor(&out[i * TF_BLOCK_SIZE], tmp);
memcpy(tmp, &in[i * TF_BLOCK_SIZE], TF_BLOCK_SIZE);
memcpy(tmp, old, TF_BLOCK_SIZE);
}
return n * TF_BLOCK_SIZE;

16
src/transform_tf.c
View File

@ -29,7 +29,7 @@
// cbc mode is being used with random value prepended to plaintext
// instead of iv so, actual iv is null_iv
uint8_t null_iv[TF_IV_SIZE] = {0};
const uint8_t null_iv[TF_IV_SIZE] = {0};
typedef struct transop_tf {
tf_context_t *ctx;
@ -70,6 +70,7 @@ static int transop_encode_tf(n2n_trans_op_t * arg,
// the assembly buffer is a source for encrypting data
// the whole contents of assembly are encrypted
uint8_t assembly[N2N_PKT_BUF_SIZE];
uint8_t assembly2[N2N_PKT_BUF_SIZE];
size_t idx = 0;
int padded_len;
uint8_t padding;
@ -83,10 +84,10 @@ static int transop_encode_tf(n2n_trans_op_t * arg,
// full block sized random value (128 bit)
// !!! replace with 2 calls to encode_uint64(...) as as available
// !!! which is still under consideration in pull request 'revAes'
encode_uint32(assembly, &idx, 0);
encode_uint32(assembly, &idx, 0);
encode_uint32(assembly, &idx, 0);
encode_uint32(assembly, &idx, 0);
encode_uint32(assembly, &idx, n2n_rand());
encode_uint32(assembly, &idx, n2n_rand());
encode_uint32(assembly, &idx, n2n_rand());
encode_uint32(assembly, &idx, n2n_rand());
// adjust for maybe differently chosen TF_PREAMBLE_SIZE
idx = TF_PREAMBLE_SIZE;
@ -100,12 +101,11 @@ static int transop_encode_tf(n2n_trans_op_t * arg,
// pad the following bytes with zero, fixed length (TF_BLOCK_SIZE) seems to compile
// to slightly faster code than run-time dependant 'padding'
memset (assembly + idx, 0, TF_BLOCK_SIZE);
tf_cbc_encrypt(outbuf, assembly, padded_len, null_iv, priv->ctx);
if(padding) {
// exchange last two cipher blocks
memcpy (buf, outbuf+padded_len - TF_BLOCK_SIZE, TF_BLOCK_SIZE);
memcpy (buf, outbuf + padded_len - TF_BLOCK_SIZE, TF_BLOCK_SIZE);
memcpy (outbuf + padded_len - TF_BLOCK_SIZE, outbuf + padded_len - 2 * TF_BLOCK_SIZE, TF_BLOCK_SIZE);
memcpy (outbuf + padded_len - 2 * TF_BLOCK_SIZE, buf, TF_BLOCK_SIZE);
}
@ -156,7 +156,9 @@ static int transop_decode_tf(n2n_trans_op_t * arg,
// write new penultimate block from buf
memcpy(assembly + penultimate_block, buf, TF_BLOCK_SIZE);
// regular cbc decryption on the re-arranged ciphertext
tf_cbc_decrypt(assembly, assembly, in_len + TF_BLOCK_SIZE - rest, null_iv, priv->ctx);
// check for expected zero padding and give a warning otherwise
if (memcmp(assembly + in_len, null_iv, TF_BLOCK_SIZE - rest)) {
traceEvent(TRACE_WARNING, "transop_decode_tf payload decryption failed with unexpected cipher text stealing padding");