Added checking of the key usage and extended key usage extensions in the

certificates.

ctaocrypt/src/asn.c

@@ -6493,6 +6493,12 @@ int ParseCRL(DecodedCRL* dcrl, const byte* buff, word32 sz, void* cm)
     if (ca) {
         CYASSL_MSG("Found CRL issuer CA");
         /* try to confirm/verify signature */
+        #ifndef IGNORE_KEY_EXTENSIONS
+            if ((ca->keyUsage & KEYUSE_CRL_SIGN) == 0) {
+                CYASSL_MSG("CA cannot sign CRLs");
+                return ASN_CRL_NO_SIGNER_E;
+            }
+        #endif /* IGNORE_KEY_EXTENSIONS */
         if (!ConfirmSignature(buff + dcrl->certBegin,
                 dcrl->sigIndex - dcrl->certBegin,
                 ca->publicKey, ca->pubKeySize, ca->keyOID,

cyassl/ctaocrypt/asn.h

@@ -426,6 +426,7 @@ struct DecodedCert {
 struct Signer {
     word32  pubKeySize;
     word32  keyOID;                  /* key type */
+    word16  keyUsage;
     byte*   publicKey;
     int     nameLen;
     char*   name;                    /* common name */

cyassl/error-ssl.h

@@ -115,6 +115,10 @@ enum CyaSSL_ErrorCodes {
     UNKNOWN_SNI_HOST_NAME_E = -281,        /* Unrecognized host name Error */
     UNKNOWN_MAX_FRAG_LEN_E  = -282,        /* Unrecognized max frag len Error */
     /* add strings to SetErrorString !!!!! */
+    KEYUSE_SIGNATURE_E      = -283,        /* KeyUse digSignature error */
+    KEYUSE_AGREEMENT_E      = -284,        /* KeyUse keyAgreement error */
+    KEYUSE_ENCIPHER_E       = -285,        /* KeyUse keyEncipher error */
+    EXTKEYUSE_AUTH_E        = -286,        /* ExtKeyUse server|client_auth */
 
     /* begin negotiation parameter errors */
     UNSUPPORTED_SUITE       = -290,        /* unsupported cipher suite */

src/internal.c

@@ -3465,6 +3465,49 @@ static int DoCertificate(CYASSL* ssl, byte* input, word32* inOutIdx,
         }
 #endif    
 
+#ifndef IGNORE_KEY_EXTENSIONS
+        if (dCert.extKeyUsageSet) {
+            if ((ssl->specs.kea == rsa_kea) &&
+                (dCert.extKeyUsage & KEYUSE_KEY_ENCIPHER) == 0) {
+                fatal = 1;
+                ret = KEYUSE_ENCIPHER_E;
+            }
+            if ((ssl->specs.kea == diffie_hellman_kea ||
+                    ssl->specs.kea == ecc_diffie_hellman_kea ||
+                    ssl->specs.kea == ecc_static_diffie_hellman_kea) &&
+                (dCert.extKeyUsage & KEYUSE_KEY_AGREE) == 0) {
+                fatal = 1;
+                ret = KEYUSE_AGREEMENT_E;
+            }
+            if ((ssl->specs.sig_algo == rsa_sa_algo ||
+                    ssl->specs.sig_algo == ecc_dsa_sa_algo) &&
+                (dCert.extKeyUsage & KEYUSE_DIGITAL_SIG) == 0) {
+                CYASSL_MSG("KeyUse Digital Sig not set");
+                fatal = 1;
+                ret = KEYUSE_SIGNATURE_E;
+            }
+        }
+
+        if (dCert.extExtKeyUsageSet) {
+            if (ssl->options.side == CYASSL_CLIENT_END) {
+                if ((dCert.extExtKeyUsage &
+                        (EXTKEYUSE_ANY | EXTKEYUSE_SERVER_AUTH)) == 0) {
+                    CYASSL_MSG("ExtKeyUse Server Auth not set");
+                    fatal = 1;
+                    ret = EXTKEYUSE_AUTH_E;
+                }
+            }
+            else {
+                if ((dCert.extExtKeyUsage &
+                        (EXTKEYUSE_ANY | EXTKEYUSE_CLIENT_AUTH)) == 0) {
+                    CYASSL_MSG("ExtKeyUse Client Auth not set");
+                    fatal = 1;
+                    ret = EXTKEYUSE_AUTH_E;
+                }
+            }
+        }
+#endif /* IGNORE_KEY_EXTENSIONS */
+
         if (fatal) {
             FreeDecodedCert(&dCert);
             ssl->error = ret;
@@ -6451,6 +6494,22 @@ void SetErrorString(int error, char* str)
         XSTRNCPY(str, "Unrecognized host name Error", max);
         break;
 
+    case KEYUSE_SIGNATURE_E:
+        XSTRNCPY(str, "Key Use digitalSignature not set Error", max);
+        break;
+
+    case KEYUSE_AGREEMENT_E:
+        XSTRNCPY(str, "Key Use keyAgreement not set Error", max);
+        break;
+
+    case KEYUSE_ENCIPHER_E:
+        XSTRNCPY(str, "Key Use keyEncipherment not set Error", max);
+        break;
+
+    case EXTKEYUSE_AUTH_E:
+        XSTRNCPY(str, "Ext Key Use server/client auth not set Error", max);
+        break;
+
     default :
         XSTRNCPY(str, "unknown error number", max);
     }

src/ssl.c

@@ -1526,6 +1526,8 @@ int AddCA(CYASSL_CERT_MANAGER* cm, buffer der, int type, int verify)
                                             cert.extSubjKeyId, SHA_DIGEST_SIZE);
             #endif
             XMEMCPY(signer->subjectNameHash, cert.subjectHash, SHA_DIGEST_SIZE);
+            signer->keyUsage = cert.extKeyUsageSet ? cert.extKeyUsage : 0xFFFF;
+                                   /* If Key Usage not set, all uses valid. */
             signer->next = NULL;   /* in case lock fails */
 
             cert.publicKey = 0;  /* don't free here */