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Zerocopy crypto_secretbox_open_easy()

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This commit is contained in:
Frank Denis 2014-06-25 20:17:50 -07:00
parent 8e22264e85
commit b2a8367b2b
1 changed files with 29 additions and 26 deletions
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55
src/libsodium/crypto_secretbox/crypto_secretbox_easy.c
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@ -68,39 +68,42 @@ crypto_secretbox_open_easy(unsigned char *m, const unsigned char *c,
unsigned long long clen, const unsigned char *n,
const unsigned char *k)
{
unsigned char *c_boxed;
unsigned char *m_boxed;
size_t c_boxed_len;
size_t m_boxed_len;
int rc;
unsigned char block0[64U];
unsigned char subkey[crypto_stream_salsa20_KEYBYTES];
unsigned long long i;
unsigned long long mlen0;
(void) sizeof(int[crypto_secretbox_BOXZEROBYTES + crypto_secretbox_MACBYTES
== crypto_secretbox_ZEROBYTES ? 1 : -1]);
if (clen < crypto_secretbox_MACBYTES ||
clen > SIZE_MAX - crypto_secretbox_BOXZEROBYTES) {
if (clen < crypto_secretbox_MACBYTES) {
return -1;
}
c_boxed_len = clen + crypto_secretbox_BOXZEROBYTES;
if ((c_boxed = (unsigned char *) malloc(c_boxed_len)) == NULL) {
crypto_core_hsalsa20(subkey, n, k, sigma);
crypto_stream_salsa20(block0, crypto_stream_salsa20_KEYBYTES,
n + 16, subkey);
if (crypto_onetimeauth_poly1305_verify(c, c + crypto_secretbox_MACBYTES,
clen - crypto_secretbox_MACBYTES,
block0) != 0) {
sodium_memzero(subkey, sizeof subkey);
return -1;
}
memset(c_boxed, 0, crypto_secretbox_BOXZEROBYTES);
memcpy(c_boxed + crypto_secretbox_BOXZEROBYTES, c, clen);
m_boxed_len = crypto_secretbox_ZEROBYTES + (clen - crypto_secretbox_MACBYTES);
if ((m_boxed = (unsigned char *) malloc(m_boxed_len)) == NULL) {
free(c_boxed);
return -1;
mlen0 = clen - crypto_secretbox_MACBYTES;
if (mlen0 > 64U - crypto_secretbox_ZEROBYTES) {
mlen0 = 64U - crypto_secretbox_ZEROBYTES;
}
rc = crypto_secretbox_open(m_boxed, c_boxed,
(unsigned long long) c_boxed_len, n, k);
free(c_boxed);
if (rc != 0) {
free(m_boxed);
return -1;
memcpy(block0 + crypto_secretbox_ZEROBYTES,
c + crypto_secretbox_MACBYTES, mlen0);
crypto_stream_salsa20_xor(block0, block0,
crypto_secretbox_ZEROBYTES + mlen0,
n + 16, subkey);
for (i = 0U; i < mlen0; i++) {
m[i] = block0[i + crypto_secretbox_ZEROBYTES];
}
memcpy(m, m_boxed + crypto_secretbox_ZEROBYTES,
clen - crypto_secretbox_MACBYTES);
free(m_boxed);
if (clen - crypto_secretbox_MACBYTES > mlen0) {
crypto_stream_salsa20_xor_ic(m + mlen0,
c + crypto_secretbox_MACBYTES + mlen0,
clen - crypto_secretbox_MACBYTES - mlen0,
n + 16, 1U, subkey);
}
sodium_memzero(subkey, sizeof subkey);
return 0;
}