/* Find the "weakest link". Get the strength of the signature and symmetric * keys and choose a curve based on the weakest of those two. */ const sslNamedGroupDef * ssl_GetECGroupForServerSocket(sslSocket *ss) { const sslServerCert *cert = ss->sec.serverCert; unsigned int certKeySize; const ssl3BulkCipherDef *bulkCipher; unsigned int requiredECCbits; PORT_Assert(cert); if (!cert || !cert->serverKeyPair || !cert->serverKeyPair->pubKey) { PORT_SetError(SSL_ERROR_NO_CYPHER_OVERLAP); return NULL; } if (cert->certType.authType == ssl_auth_rsa_sign) { certKeySize = SECKEY_PublicKeyStrengthInBits(cert->serverKeyPair->pubKey); certKeySize = SSL_RSASTRENGTH_TO_ECSTRENGTH(certKeySize); } else if (cert->certType.authType == ssl_auth_ecdsa || cert->certType.authType == ssl_auth_ecdh_rsa || cert->certType.authType == ssl_auth_ecdh_ecdsa) { const sslNamedGroupDef *groupDef = cert->certType.namedCurve; /* We won't select a certificate unless the named curve has been * negotiated (or supported_curves was absent), double check that. */ PORT_Assert(groupDef->keaType == ssl_kea_ecdh); PORT_Assert(ssl_NamedGroupEnabled(ss, groupDef)); if (!ssl_NamedGroupEnabled(ss, groupDef)) { return NULL; } certKeySize = groupDef->bits; } else { PORT_Assert(0); return NULL; } bulkCipher = ssl_GetBulkCipherDef(ss->ssl3.hs.suite_def); requiredECCbits = bulkCipher->key_size * BPB * 2; PORT_Assert(requiredECCbits || ss->ssl3.hs.suite_def->bulk_cipher_alg == cipher_null); if (requiredECCbits > certKeySize) { requiredECCbits = certKeySize; } return ssl_GetECGroupWithStrength(ss, requiredECCbits); }
// This function guesses what key exchange strength libssl will choose. PRUint32 SSLInt_DetermineKEABits(PRUint16 serverKeyBits, const SSLCipherSuiteInfo *info) { PRUint32 authBits; SSLAuthType authAlgorithm = info->authType; if (authAlgorithm == ssl_auth_ecdsa || authAlgorithm == ssl_auth_ecdh_rsa || authAlgorithm == ssl_auth_ecdh_ecdsa) { authBits = serverKeyBits; } else { PORT_Assert(authAlgorithm == ssl_auth_rsa_decrypt || authAlgorithm == ssl_auth_rsa_sign); authBits = SSL_RSASTRENGTH_TO_ECSTRENGTH(serverKeyBits); } // We expect a curve for key exchange to be selected based on the symmetric // key strength (times 2) or the server key size, whichever is smaller. PRUint32 targetKeaBits = PR_MIN(info->symKeyBits * 2, authBits); // P-256 is the preferred curve of minimum size. return PR_MAX(256U, targetKeaBits); }
/* Find the "weakest link". Get the strength of the signature and symmetric * keys and choose a curve based on the weakest of those two. */ const namedGroupDef * ssl_GetECGroupForServerSocket(sslSocket *ss) { const sslServerCert *cert = ss->sec.serverCert; int certKeySize; int requiredECCbits = ss->sec.secretKeyBits * 2; PORT_Assert(cert); if (!cert || !cert->serverKeyPair || !cert->serverKeyPair->pubKey) { PORT_SetError(SSL_ERROR_NO_CYPHER_OVERLAP); return NULL; } if (cert->certType.authType == ssl_auth_rsa_sign) { certKeySize = SECKEY_PublicKeyStrengthInBits(cert->serverKeyPair->pubKey); certKeySize = SSL_RSASTRENGTH_TO_ECSTRENGTH(certKeySize); } else if (cert->certType.authType == ssl_auth_ecdsa || cert->certType.authType == ssl_auth_ecdh_rsa || cert->certType.authType == ssl_auth_ecdh_ecdsa) { const namedGroupDef *groupDef = cert->certType.namedCurve; /* We won't select a certificate unless the named curve has been * negotiated (or supported_curves was absent), double check that. */ PORT_Assert(groupDef->type == group_type_ec); PORT_Assert(ssl_NamedGroupEnabled(ss, groupDef)); if (!ssl_NamedGroupEnabled(ss, groupDef)) { return NULL; } certKeySize = groupDef->bits; } else { PORT_Assert(0); return NULL; } if (requiredECCbits > certKeySize) { requiredECCbits = certKeySize; } return ssl_GetECGroupWithStrength(ss->namedGroups, requiredECCbits); }
SECStatus SSL_CanBypass(CERTCertificate *cert, SECKEYPrivateKey *srvPrivkey, PRUint32 protocolmask, PRUint16 *ciphersuites, int nsuites, PRBool *pcanbypass, void *pwArg) { SECStatus rv; int i; PRUint16 suite; PK11SymKey * pms = NULL; SECKEYPublicKey * srvPubkey = NULL; KeyType privKeytype; PK11SlotInfo * slot = NULL; SECItem param; CK_VERSION version; CK_MECHANISM_TYPE mechanism_array[2]; SECItem enc_pms = {siBuffer, NULL, 0}; PRBool isTLS = PR_FALSE; SSLCipherSuiteInfo csdef; PRBool testrsa = PR_FALSE; PRBool testrsa_export = PR_FALSE; PRBool testecdh = PR_FALSE; PRBool testecdhe = PR_FALSE; #ifdef NSS_ENABLE_ECC SECKEYECParams ecParams = { siBuffer, NULL, 0 }; #endif if (!cert || !srvPrivkey || !ciphersuites || !pcanbypass) { PORT_SetError(SEC_ERROR_INVALID_ARGS); return SECFailure; } srvPubkey = CERT_ExtractPublicKey(cert); if (!srvPubkey) return SECFailure; *pcanbypass = PR_TRUE; rv = SECFailure; /* determine which KEAs to test */ /* 0 (SSL_NULL_WITH_NULL_NULL) is used as a list terminator because * SSL3 and TLS specs forbid negotiating that cipher suite number. */ for (i=0; i < nsuites && (suite = *ciphersuites++) != 0; i++) { /* skip SSL2 cipher suites and ones NSS doesn't support */ if (SSL_GetCipherSuiteInfo(suite, &csdef, sizeof(csdef)) != SECSuccess || SSL_IS_SSL2_CIPHER(suite) ) continue; switch (csdef.keaType) { case ssl_kea_rsa: switch (csdef.cipherSuite) { case TLS_RSA_EXPORT1024_WITH_RC4_56_SHA: case TLS_RSA_EXPORT1024_WITH_DES_CBC_SHA: case SSL_RSA_EXPORT_WITH_RC4_40_MD5: case SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5: testrsa_export = PR_TRUE; } if (!testrsa_export) testrsa = PR_TRUE; break; case ssl_kea_ecdh: if (strcmp(csdef.keaTypeName, "ECDHE") == 0) /* ephemeral? */ testecdhe = PR_TRUE; else testecdh = PR_TRUE; break; case ssl_kea_dh: /* this is actually DHE */ default: continue; } } /* For each protocol try to derive and extract an MS. * Failure of function any function except MS extract means * continue with the next cipher test. Stop testing when the list is * exhausted or when the first MS extract--not derive--fails. */ privKeytype = SECKEY_GetPrivateKeyType(srvPrivkey); protocolmask &= SSL_CBP_SSL3|SSL_CBP_TLS1_0; while (protocolmask) { if (protocolmask & SSL_CBP_SSL3) { isTLS = PR_FALSE; protocolmask ^= SSL_CBP_SSL3; } else { isTLS = PR_TRUE; protocolmask ^= SSL_CBP_TLS1_0; } if (privKeytype == rsaKey && testrsa_export) { if (PK11_GetPrivateModulusLen(srvPrivkey) > EXPORT_RSA_KEY_LENGTH) { *pcanbypass = PR_FALSE; rv = SECSuccess; break; } else testrsa = PR_TRUE; } for (; privKeytype == rsaKey && testrsa; ) { /* TLS_RSA */ unsigned char rsaPmsBuf[SSL3_RSA_PMS_LENGTH]; unsigned int outLen = 0; CK_MECHANISM_TYPE target; SECStatus irv; mechanism_array[0] = CKM_SSL3_PRE_MASTER_KEY_GEN; mechanism_array[1] = CKM_RSA_PKCS; slot = PK11_GetBestSlotMultiple(mechanism_array, 2, pwArg); if (slot == NULL) { PORT_SetError(SSL_ERROR_TOKEN_SLOT_NOT_FOUND); break; } /* Generate the pre-master secret ... (client side) */ version.major = 3 /*MSB(clientHelloVersion)*/; version.minor = 0 /*LSB(clientHelloVersion)*/; param.data = (unsigned char *)&version; param.len = sizeof version; pms = PK11_KeyGen(slot, CKM_SSL3_PRE_MASTER_KEY_GEN, ¶m, 0, pwArg); PK11_FreeSlot(slot); if (!pms) break; /* now wrap it */ enc_pms.len = SECKEY_PublicKeyStrength(srvPubkey); enc_pms.data = (unsigned char*)PORT_Alloc(enc_pms.len); if (enc_pms.data == NULL) { PORT_SetError(PR_OUT_OF_MEMORY_ERROR); break; } irv = PK11_PubWrapSymKey(CKM_RSA_PKCS, srvPubkey, pms, &enc_pms); if (irv != SECSuccess) break; PK11_FreeSymKey(pms); pms = NULL; /* now do the server side--check the triple bypass first */ rv = PK11_PrivDecryptPKCS1(srvPrivkey, rsaPmsBuf, &outLen, sizeof rsaPmsBuf, (unsigned char *)enc_pms.data, enc_pms.len); /* if decrypt worked we're done with the RSA test */ if (rv == SECSuccess) { *pcanbypass = PR_TRUE; break; } /* check for fallback to double bypass */ target = isTLS ? CKM_TLS_MASTER_KEY_DERIVE : CKM_SSL3_MASTER_KEY_DERIVE; pms = PK11_PubUnwrapSymKey(srvPrivkey, &enc_pms, target, CKA_DERIVE, 0); rv = ssl_canExtractMS(pms, isTLS, PR_FALSE, pcanbypass); if (rv == SECSuccess && *pcanbypass == PR_FALSE) goto done; break; } /* Check for NULL to avoid double free. * SECItem_FreeItem sets data NULL in secitem.c#265 */ if (enc_pms.data != NULL) { SECITEM_FreeItem(&enc_pms, PR_FALSE); } #ifdef NSS_ENABLE_ECC for (; (privKeytype == ecKey && ( testecdh || testecdhe)) || (privKeytype == rsaKey && testecdhe); ) { CK_MECHANISM_TYPE target; SECKEYPublicKey *keapub = NULL; SECKEYPrivateKey *keapriv; SECKEYPublicKey *cpub = NULL; /* client's ephemeral ECDH keys */ SECKEYPrivateKey *cpriv = NULL; SECKEYECParams *pecParams = NULL; if (privKeytype == ecKey && testecdhe) { /* TLS_ECDHE_ECDSA */ pecParams = &srvPubkey->u.ec.DEREncodedParams; } else if (privKeytype == rsaKey && testecdhe) { /* TLS_ECDHE_RSA */ ECName ec_curve; int serverKeyStrengthInBits; int signatureKeyStrength; int requiredECCbits; /* find a curve of equivalent strength to the RSA key's */ requiredECCbits = PK11_GetPrivateModulusLen(srvPrivkey); if (requiredECCbits < 0) break; requiredECCbits *= BPB; serverKeyStrengthInBits = srvPubkey->u.rsa.modulus.len; if (srvPubkey->u.rsa.modulus.data[0] == 0) { serverKeyStrengthInBits--; } /* convert to strength in bits */ serverKeyStrengthInBits *= BPB; signatureKeyStrength = SSL_RSASTRENGTH_TO_ECSTRENGTH(serverKeyStrengthInBits); if ( requiredECCbits > signatureKeyStrength ) requiredECCbits = signatureKeyStrength; ec_curve = ssl3_GetCurveWithECKeyStrength(SSL3_SUPPORTED_CURVES_MASK, requiredECCbits); rv = ssl3_ECName2Params(NULL, ec_curve, &ecParams); if (rv == SECFailure) { break; } pecParams = &ecParams; } if (testecdhe) { /* generate server's ephemeral keys */ keapriv = SECKEY_CreateECPrivateKey(pecParams, &keapub, NULL); if (!keapriv || !keapub) { if (keapriv) SECKEY_DestroyPrivateKey(keapriv); if (keapub) SECKEY_DestroyPublicKey(keapub); PORT_SetError(SEC_ERROR_KEYGEN_FAIL); rv = SECFailure; break; } } else { /* TLS_ECDH_ECDSA */ keapub = srvPubkey; keapriv = srvPrivkey; pecParams = &srvPubkey->u.ec.DEREncodedParams; } /* perform client side ops */ /* generate a pair of ephemeral keys using server's parms */ cpriv = SECKEY_CreateECPrivateKey(pecParams, &cpub, NULL); if (!cpriv || !cpub) { if (testecdhe) { SECKEY_DestroyPrivateKey(keapriv); SECKEY_DestroyPublicKey(keapub); } PORT_SetError(SEC_ERROR_KEYGEN_FAIL); rv = SECFailure; break; } /* now do the server side */ /* determine the PMS using client's public value */ target = isTLS ? CKM_TLS_MASTER_KEY_DERIVE_DH : CKM_SSL3_MASTER_KEY_DERIVE_DH; pms = PK11_PubDeriveWithKDF(keapriv, cpub, PR_FALSE, NULL, NULL, CKM_ECDH1_DERIVE, target, CKA_DERIVE, 0, CKD_NULL, NULL, NULL); rv = ssl_canExtractMS(pms, isTLS, PR_TRUE, pcanbypass); SECKEY_DestroyPrivateKey(cpriv); SECKEY_DestroyPublicKey(cpub); if (testecdhe) { SECKEY_DestroyPrivateKey(keapriv); SECKEY_DestroyPublicKey(keapub); } if (rv == SECSuccess && *pcanbypass == PR_FALSE) goto done; break; } /* Check for NULL to avoid double free. */ if (ecParams.data != NULL) { PORT_Free(ecParams.data); ecParams.data = NULL; } #endif /* NSS_ENABLE_ECC */ if (pms) PK11_FreeSymKey(pms); } /* *pcanbypass has been set */ rv = SECSuccess; done: if (pms) PK11_FreeSymKey(pms); /* Check for NULL to avoid double free. * SECItem_FreeItem sets data NULL in secitem.c#265 */ if (enc_pms.data != NULL) { SECITEM_FreeItem(&enc_pms, PR_FALSE); } #ifdef NSS_ENABLE_ECC if (ecParams.data != NULL) { PORT_Free(ecParams.data); ecParams.data = NULL; } #endif /* NSS_ENABLE_ECC */ if (srvPubkey) { SECKEY_DestroyPublicKey(srvPubkey); srvPubkey = NULL; } return rv; }
SECStatus SSL_CanBypass(CERTCertificate *cert, SECKEYPrivateKey *srvPrivkey, PRUint32 protocolmask, PRUint16 *ciphersuites, int nsuites, PRBool *pcanbypass, void *pwArg) { #ifdef NO_PKCS11_BYPASS if (!pcanbypass) { PORT_SetError(SEC_ERROR_INVALID_ARGS); return SECFailure; } *pcanbypass = PR_FALSE; return SECSuccess; #else SECStatus rv; int i; PRUint16 suite; PK11SymKey * pms = NULL; SECKEYPublicKey * srvPubkey = NULL; KeyType privKeytype; PK11SlotInfo * slot = NULL; SECItem param; CK_VERSION version; CK_MECHANISM_TYPE mechanism_array[2]; SECItem enc_pms = {siBuffer, NULL, 0}; PRBool isTLS = PR_FALSE; SSLCipherSuiteInfo csdef; PRBool testrsa = PR_FALSE; PRBool testrsa_export = PR_FALSE; PRBool testecdh = PR_FALSE; PRBool testecdhe = PR_FALSE; #ifdef NSS_ENABLE_ECC SECKEYECParams ecParams = { siBuffer, NULL, 0 }; #endif if (!cert || !srvPrivkey || !ciphersuites || !pcanbypass) { PORT_SetError(SEC_ERROR_INVALID_ARGS); return SECFailure; } srvPubkey = CERT_ExtractPublicKey(cert); if (!srvPubkey) return SECFailure; *pcanbypass = PR_TRUE; rv = SECFailure; for (i=0; i < nsuites && (suite = *ciphersuites++) != 0; i++) { if (SSL_GetCipherSuiteInfo(suite, &csdef, sizeof(csdef)) != SECSuccess || SSL_IS_SSL2_CIPHER(suite) ) continue; switch (csdef.keaType) { case ssl_kea_rsa: switch (csdef.cipherSuite) { case TLS_RSA_EXPORT1024_WITH_RC4_56_SHA: case TLS_RSA_EXPORT1024_WITH_DES_CBC_SHA: case SSL_RSA_EXPORT_WITH_RC4_40_MD5: case SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5: testrsa_export = PR_TRUE; } if (!testrsa_export) testrsa = PR_TRUE; break; case ssl_kea_ecdh: if (strcmp(csdef.keaTypeName, "ECDHE") == 0) testecdhe = PR_TRUE; else testecdh = PR_TRUE; break; case ssl_kea_dh: default: continue; } } privKeytype = SECKEY_GetPrivateKeyType(srvPrivkey); protocolmask &= SSL_CBP_SSL3|SSL_CBP_TLS1_0; while (protocolmask) { if (protocolmask & SSL_CBP_SSL3) { isTLS = PR_FALSE; protocolmask ^= SSL_CBP_SSL3; } else { isTLS = PR_TRUE; protocolmask ^= SSL_CBP_TLS1_0; } if (privKeytype == rsaKey && testrsa_export) { if (PK11_GetPrivateModulusLen(srvPrivkey) > EXPORT_RSA_KEY_LENGTH) { *pcanbypass = PR_FALSE; rv = SECSuccess; break; } else testrsa = PR_TRUE; } for (; privKeytype == rsaKey && testrsa; ) { unsigned char rsaPmsBuf[SSL3_RSA_PMS_LENGTH]; unsigned int outLen = 0; CK_MECHANISM_TYPE target; SECStatus irv; mechanism_array[0] = CKM_SSL3_PRE_MASTER_KEY_GEN; mechanism_array[1] = CKM_RSA_PKCS; slot = PK11_GetBestSlotMultiple(mechanism_array, 2, pwArg); if (slot == NULL) { PORT_SetError(SSL_ERROR_TOKEN_SLOT_NOT_FOUND); break; } version.major = 3 ; version.minor = 0 ; param.data = (unsigned char *)&version; param.len = sizeof version; pms = PK11_KeyGen(slot, CKM_SSL3_PRE_MASTER_KEY_GEN, ¶m, 0, pwArg); PK11_FreeSlot(slot); if (!pms) break; enc_pms.len = SECKEY_PublicKeyStrength(srvPubkey); enc_pms.data = (unsigned char*)PORT_Alloc(enc_pms.len); if (enc_pms.data == NULL) { PORT_SetError(PR_OUT_OF_MEMORY_ERROR); break; } irv = PK11_PubWrapSymKey(CKM_RSA_PKCS, srvPubkey, pms, &enc_pms); if (irv != SECSuccess) break; PK11_FreeSymKey(pms); pms = NULL; rv = PK11_PrivDecryptPKCS1(srvPrivkey, rsaPmsBuf, &outLen, sizeof rsaPmsBuf, (unsigned char *)enc_pms.data, enc_pms.len); if (rv == SECSuccess) { *pcanbypass = PR_TRUE; break; } target = isTLS ? CKM_TLS_MASTER_KEY_DERIVE : CKM_SSL3_MASTER_KEY_DERIVE; pms = PK11_PubUnwrapSymKey(srvPrivkey, &enc_pms, target, CKA_DERIVE, 0); rv = ssl_canExtractMS(pms, isTLS, PR_FALSE, pcanbypass); if (rv == SECSuccess && *pcanbypass == PR_FALSE) goto done; break; } if (enc_pms.data != NULL) { SECITEM_FreeItem(&enc_pms, PR_FALSE); } #ifdef NSS_ENABLE_ECC for (; (privKeytype == ecKey && ( testecdh || testecdhe)) || (privKeytype == rsaKey && testecdhe); ) { CK_MECHANISM_TYPE target; SECKEYPublicKey *keapub = NULL; SECKEYPrivateKey *keapriv; SECKEYPublicKey *cpub = NULL; SECKEYPrivateKey *cpriv = NULL; SECKEYECParams *pecParams = NULL; if (privKeytype == ecKey && testecdhe) { pecParams = &srvPubkey->u.ec.DEREncodedParams; } else if (privKeytype == rsaKey && testecdhe) { ECName ec_curve; int serverKeyStrengthInBits; int signatureKeyStrength; int requiredECCbits; requiredECCbits = PK11_GetPrivateModulusLen(srvPrivkey); if (requiredECCbits < 0) break; requiredECCbits *= BPB; serverKeyStrengthInBits = srvPubkey->u.rsa.modulus.len; if (srvPubkey->u.rsa.modulus.data[0] == 0) { serverKeyStrengthInBits--; } serverKeyStrengthInBits *= BPB; signatureKeyStrength = SSL_RSASTRENGTH_TO_ECSTRENGTH(serverKeyStrengthInBits); if ( requiredECCbits > signatureKeyStrength ) requiredECCbits = signatureKeyStrength; ec_curve = ssl3_GetCurveWithECKeyStrength( ssl3_GetSupportedECCurveMask(NULL), requiredECCbits); rv = ssl3_ECName2Params(NULL, ec_curve, &ecParams); if (rv == SECFailure) { break; } pecParams = &ecParams; } if (testecdhe) { keapriv = SECKEY_CreateECPrivateKey(pecParams, &keapub, NULL); if (!keapriv || !keapub) { if (keapriv) SECKEY_DestroyPrivateKey(keapriv); if (keapub) SECKEY_DestroyPublicKey(keapub); PORT_SetError(SEC_ERROR_KEYGEN_FAIL); rv = SECFailure; break; } } else { keapub = srvPubkey; keapriv = srvPrivkey; pecParams = &srvPubkey->u.ec.DEREncodedParams; } cpriv = SECKEY_CreateECPrivateKey(pecParams, &cpub, NULL); if (!cpriv || !cpub) { if (testecdhe) { SECKEY_DestroyPrivateKey(keapriv); SECKEY_DestroyPublicKey(keapub); } PORT_SetError(SEC_ERROR_KEYGEN_FAIL); rv = SECFailure; break; } target = isTLS ? CKM_TLS_MASTER_KEY_DERIVE_DH : CKM_SSL3_MASTER_KEY_DERIVE_DH; pms = PK11_PubDeriveWithKDF(keapriv, cpub, PR_FALSE, NULL, NULL, CKM_ECDH1_DERIVE, target, CKA_DERIVE, 0, CKD_NULL, NULL, NULL); rv = ssl_canExtractMS(pms, isTLS, PR_TRUE, pcanbypass); SECKEY_DestroyPrivateKey(cpriv); SECKEY_DestroyPublicKey(cpub); if (testecdhe) { SECKEY_DestroyPrivateKey(keapriv); SECKEY_DestroyPublicKey(keapub); } if (rv == SECSuccess && *pcanbypass == PR_FALSE) goto done; break; } if (ecParams.data != NULL) { PORT_Free(ecParams.data); ecParams.data = NULL; } #endif if (pms) PK11_FreeSymKey(pms); } rv = SECSuccess; done: if (pms) PK11_FreeSymKey(pms); if (enc_pms.data != NULL) { SECITEM_FreeItem(&enc_pms, PR_FALSE); } #ifdef NSS_ENABLE_ECC if (ecParams.data != NULL) { PORT_Free(ecParams.data); ecParams.data = NULL; } #endif if (srvPubkey) { SECKEY_DestroyPublicKey(srvPubkey); srvPubkey = NULL; } return rv; #endif }