/*
* Verify a plaintext password against a SCRAM verifier. This is used when
* performing plaintext password authentication for a user that has a SCRAM
* verifier stored in pg_authid.
*/
bool
scram_verify_plain_password(const char *username, const char *password,
const char *verifier)
{
char *encoded_salt;
char *salt;
int saltlen;
int iterations;
uint8 salted_password[SCRAM_KEY_LEN];
uint8 stored_key[SCRAM_KEY_LEN];
uint8 server_key[SCRAM_KEY_LEN];
uint8 computed_key[SCRAM_KEY_LEN];
char *prep_password = NULL;
pg_saslprep_rc rc;
if (!parse_scram_verifier(verifier, &iterations, &encoded_salt,
stored_key, server_key))
{
/*
* The password looked like a SCRAM verifier, but could not be parsed.
*/
ereport(LOG,
(errmsg("invalid SCRAM verifier for user \"%s\"", username)));
return false;
}
salt = palloc(pg_b64_dec_len(strlen(encoded_salt)));
saltlen = pg_b64_decode(encoded_salt, strlen(encoded_salt), salt);
if (saltlen == -1)
{
ereport(LOG,
(errmsg("invalid SCRAM verifier for user \"%s\"", username)));
return false;
}
/* Normalize the password */
rc = pg_saslprep(password, &prep_password);
if (rc == SASLPREP_SUCCESS)
password = prep_password;
/* Compute Server Key based on the user-supplied plaintext password */
scram_SaltedPassword(password, salt, saltlen, iterations, salted_password);
scram_ServerKey(salted_password, computed_key);
if (prep_password)
pfree(prep_password);
/*
* Compare the verifier's Server Key with the one computed from the
* user-supplied password.
*/
return memcmp(computed_key, server_key, SCRAM_KEY_LEN) == 0;
}
/*
* Calculate ClientKey or ServerKey.
*/
void
scram_ClientOrServerKey(const char *password,
const char *salt, int saltlen, int iterations,
const char *keystr, uint8 *result)
{
uint8 keybuf[SCRAM_KEY_LEN];
scram_HMAC_ctx ctx;
scram_SaltedPassword(password, salt, saltlen, iterations, keybuf);
scram_HMAC_init(&ctx, keybuf, SCRAM_KEY_LEN);
scram_HMAC_update(&ctx, keystr, strlen(keystr));
scram_HMAC_final(result, &ctx);
}
