void
sha1_hmac_init(struct sha1_hmac_context *ctx, const byte *key, uint keylen)
{
byte keybuf[SHA1_BLOCK_SIZE], buf[SHA1_BLOCK_SIZE];
/* Hash the key if necessary */
if (keylen <= SHA1_BLOCK_SIZE)
{
memcpy(keybuf, key, keylen);
memset(keybuf + keylen, 0, SHA1_BLOCK_SIZE - keylen);
}
else
{
sha1_hash_buffer(keybuf, key, keylen);
memset(keybuf + SHA1_SIZE, 0, SHA1_BLOCK_SIZE - SHA1_SIZE);
}
/* Initialize the inner digest */
sha1_init(&ctx->ictx);
int i;
for (i = 0; i < SHA1_BLOCK_SIZE; i++)
buf[i] = keybuf[i] ^ 0x36;
sha1_update(&ctx->ictx, buf, SHA1_BLOCK_SIZE);
/* Initialize the outer digest */
sha1_init(&ctx->octx);
for (i = 0; i < SHA1_BLOCK_SIZE; i++)
buf[i] = keybuf[i] ^ 0x5c;
sha1_update(&ctx->octx, buf, SHA1_BLOCK_SIZE);
}
static gpg_error_t
my_hash_buffer (void *arg, const char *oid,
const void *buffer, size_t length, size_t resultsize,
unsigned char *result, size_t *resultlen)
{
(void)arg; /* Not used. */
if (oid && strcmp (oid, "1.3.14.3.2.26"))
return gpg_error (GPG_ERR_NOT_SUPPORTED); /* We only support SHA-1. */
if (resultsize < 20)
return gpg_error (GPG_ERR_BUFFER_TOO_SHORT);
sha1_hash_buffer (result, buffer, length);
*resultlen = 20;
return 0;
}
