negotiating ECDSA ciphers and sigalgs in TLS 1.2

tlsfuzzer · Apr 1, 2019 · 495e716 · 495e716
1 parent b6203c7
commit 495e716
Showing 1 changed file with 20 additions and 4 deletions.
diff --git a/tlslite/tlsconnection.py b/tlslite/tlsconnection.py
@@ -2114,7 +2114,8 @@ def _handshakeServerAsyncHelper(self, verifierDB,
         # Perform a certificate-based key exchange
         elif (cipherSuite in CipherSuite.certSuites or
               cipherSuite in CipherSuite.dheCertSuites or
-              cipherSuite in CipherSuite.ecdheCertSuites):
+              cipherSuite in CipherSuite.ecdheCertSuites or
+              cipherSuite in CipherSuite.ecdheEcdsaSuites):
             if cipherSuite in CipherSuite.certSuites:
                 keyExchange = RSAKeyExchange(cipherSuite,
                                              clientHello,
@@ -2128,7 +2129,8 @@ def _handshakeServerAsyncHelper(self, verifierDB,
                                                  privateKey,
                                                  settings.dhParams,
                                                  dhGroups)
-            elif cipherSuite in CipherSuite.ecdheCertSuites:
+            elif cipherSuite in CipherSuite.ecdheCertSuites or \
+                    cipherSuite in CipherSuite.ecdheEcdsaSuites:
                 acceptedCurves = self._curveNamesToList(settings)
                 defaultCurve = getattr(GroupName, settings.defaultCurve)
                 keyExchange = ECDHE_RSAKeyExchange(cipherSuite,
@@ -3114,6 +3116,7 @@ def _serverGetClientHello(self, settings, cert_chain, verifierDB,
                 cipherSuites += CipherSuite.getTLS13Suites(settings,
                                                            version)
             if ecGroupIntersect:
+                cipherSuites += CipherSuite.getEcdsaSuites(settings, version)
                 cipherSuites += CipherSuite.getEcdheCertSuites(settings,
                                                                version)
             if ffGroupIntersect:
@@ -3968,11 +3971,11 @@ def _pickServerKeyExchangeSig(settings, clientHello, certList=None,
         supported = TLSConnection._sigHashesToList(settings,
                                                    certList=certList,
                                                    version=version)
-
         for schemeID in supported:
             if schemeID in hashAndAlgsExt.sigalgs:
                 name = SignatureScheme.toRepr(schemeID)
-                if not name and schemeID[1] == SignatureAlgorithm.rsa:
+                if not name and schemeID[1] in (SignatureAlgorithm.rsa,
+                                                SignatureAlgorithm.ecdsa):
                     name = HashAlgorithm.toRepr(schemeID[0])
 
                 if name:
@@ -3992,6 +3995,19 @@ def _sigHashesToList(settings, privateKey=None, certList=None,
         sigAlgs = []
 
         for hashName in settings.ecdsaSigHashes:
+            # only SHA256, SHA384 and SHA512 are allowed in TLS 1.3
+            if version > (3, 3) and hashName in ("sha1", "sha224"):
+                continue
+
+            # in TLS 1.3 ECDSA key curve is bound to hash
+            if privateKey and version > (3, 3):
+                if len(privateKey) == 256 and hashName != "sha256":
+                    continue
+                if len(privateKey) == 384 and hashName != "sha384":
+                    continue
+                if len(privateKey) == 521 and hashName != "sha512":
+                    continue
+
             sigAlgs.append((getattr(HashAlgorithm, hashName),
                             SignatureAlgorithm.ecdsa))