ckolivas/lrzip
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Centralise where all encryption/decryption is done, and whether to carry over the IV or not.

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This commit is contained in:
ckolivas 2011-03-17 14:10:58 +11:00
parent 9d496236c5
commit 4bc23ee001
5 changed files with 71 additions and 88 deletions
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60
util.c
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@ -150,3 +150,63 @@ void get_rand(uchar *buf, int len)
fatal("Failed to close fd in get_rand\n");
}
}
static void xor128 (void *pa, const void *pb)
{
i64 *a = pa;
const i64 *b = pb;
a [0] ^= b [0];
a [1] ^= b [1];
}
void lrz_crypt(rzip_control *control, uchar *buf, i64 len, int encrypt, int carry_iv)
{
/* Encryption requires CBC_LEN blocks so we can use ciphertext
* stealing to not have to pad the block */
unsigned char ivec[CBC_LEN], tmp0[CBC_LEN], tmp1[CBC_LEN];
i64 N, M;
mlock(ivec, CBC_LEN);
memcpy(ivec, control->hash_iv, CBC_LEN);
M = len % CBC_LEN;
N = len - M;
if (encrypt) {
print_maxverbose("Encrypting data \n");
aes_crypt_cbc(&control->aes_ctx, AES_ENCRYPT, N, ivec, buf, buf);
if (M) {
memset(tmp0, 0, sizeof(tmp0));
memcpy(tmp0, buf + N, M);
aes_crypt_cbc(&control->aes_ctx, AES_ENCRYPT, CBC_LEN,
ivec, tmp0, tmp1);
memcpy(buf + N, buf + N - CBC_LEN, M);
memcpy(buf + N - CBC_LEN, tmp1, CBC_LEN);
}
} else {
print_maxverbose("Decrypting data \n");
if (M) {
aes_crypt_cbc(&control->aes_ctx, AES_DECRYPT, N - CBC_LEN,
ivec, buf, buf);
aes_crypt_ecb(&control->aes_ctx, AES_DECRYPT,
buf + N - CBC_LEN, tmp0);
memset(tmp1, 0, CBC_LEN);
memcpy(tmp1, buf + N, M);
xor128(tmp0, tmp1);
memcpy(buf + N, tmp0, M);
memcpy(tmp1 + M, tmp0 + M, CBC_LEN - M);
aes_crypt_ecb(&control->aes_ctx, AES_DECRYPT, tmp1,
buf + N - CBC_LEN);
xor128(buf + N - CBC_LEN, ivec);
} else
aes_crypt_cbc(&control->aes_ctx, AES_DECRYPT, len,
ivec, buf, buf);
}
/* The carry_iv flag tells us if we want to update the value in
* control->hash_iv for later encryption */
if (carry_iv)
memcpy(control->hash_iv, ivec, CBC_LEN);
memset(ivec, 0, CBC_LEN);
munlock(ivec, CBC_LEN);
}