tls-crypto: Distinguish between signing and verifying signature schemes

strongSwan supports RSA_PSS_RSAE schemes for signing but does not
differentiate between rsaEncryption and rsassaPss encoding. Thus
RSA_PSS_PSS schemes are only used for verifying signatures.

diff --git a/src/libtls/tls_crypto.c b/src/libtls/tls_crypto.c
index 86fafb4dd433e1e2e36b76a2829c2cb7d00c04de..fc74d31f2e62a672780f107caf9fb32b7903d462 100644 (file)
--- a/src/libtls/tls_crypto.c
+++ b/src/libtls/tls_crypto.c
@@ -1512,19 +1512,18 @@ METHOD(tls_crypto_t, get_signature_algorithms, void,
 /**
  * Get the signature parameters from a TLS signature scheme
  */
-static signature_params_t *params_for_scheme(tls_signature_scheme_t sig)
+static signature_params_t *params_for_scheme(tls_signature_scheme_t sig,
+                                                                                        bool sign)
 {
        int i;
 
        for (i = 0; i < countof(schemes); i++)
        {
                /* strongSwan supports only RSA_PSS_RSAE schemes for signing but can
-                * verify public keys in rsaEncryption as well as rsassaPss encoding.
-                * Current implementation does not distinguish between signing and
-                * verifying. */
-               if (sig == TLS_SIG_RSA_PSS_PSS_SHA256 ||
-                       sig == TLS_SIG_RSA_PSS_PSS_SHA384 ||
-                       sig == TLS_SIG_RSA_PSS_PSS_SHA512)
+                * verify public keys in rsaEncryption as well as rsassaPss encoding. */
+               if (sign && (sig == TLS_SIG_RSA_PSS_PSS_SHA256 ||
+                                        sig == TLS_SIG_RSA_PSS_PSS_SHA384 ||
+                                        sig == TLS_SIG_RSA_PSS_PSS_SHA512))
                {
                        continue;
                }
@@ -1765,7 +1764,7 @@ METHOD(tls_crypto_t, sign, bool,
                {
                        if (reader->read_uint16(reader, &scheme))
                        {
-                               params = params_for_scheme(scheme);
+                               params = params_for_scheme(scheme, TRUE);
                                if (params &&
                                        type == key_type_from_signature_scheme(params->scheme) &&
                                        key->sign(key, params->scheme, params->params, data, &sig))
@@ -1840,7 +1839,7 @@ METHOD(tls_crypto_t, verify, bool,
                        DBG1(DBG_TLS, "received invalid signature");
                        return FALSE;
                }
-               params = params_for_scheme(scheme);
+               params = params_for_scheme(scheme, FALSE);
                if (!params)
                {
                        DBG1(DBG_TLS, "signature algorithms %N not supported",