add wc_EccPublicKeyToDer function

.gitignore

@@ -71,6 +71,7 @@ ntru-cert.pem
 ntru-key.raw
 key.der
 key.pem
+ecc-public-key.der
 ecc-key.der
 ecc-key.pem
 certreq.der

wolfcrypt/src/asn.c

@@ -5877,9 +5877,8 @@ static int SetSerial(const byte* serial, byte* output)
     return length + CTC_SERIAL_SIZE;
 }
 
-
-#ifdef HAVE_ECC
-
+#endif /* defined(WOLFSSL_CERT_GEN) && !defined(NO_RSA) */
+#if defined(HAVE_ECC) && (defined(WOLFSSL_CERT_GEN) || defined(WOLFSSL_KEY_GEN))
 
 /* Write a public ECC key to output */
 static int SetEccPublicKey(byte* output, ecc_key* key, int with_header)
@@ -5978,8 +5977,38 @@ static int SetEccPublicKey(byte* output, ecc_key* key, int with_header)
 }
 
 
-#endif /* HAVE_ECC */
+/* returns the size of buffer used, the public ECC key in DER format is stored
+   in output buffer
+   with_AlgCurve is a flag for when to include a header that has the Algorithm
+   and Curve infromation */
+int wc_EccPublicKeyToDer(ecc_key* key, byte* output, word32 inLen,
+                                                              int with_AlgCurve)
+{
+    word32 infoSz = 0;
 
+    if (output == NULL || key == NULL) {
+        return BAD_FUNC_ARG;
+    }
+
+    if (with_AlgCurve) {
+        int maxSetLength = 4; /* max buffer space needed for SetLength        */
+        int asnBit = 1;       /* buffer space needed for asn bit string macro */
+
+        infoSz += asnBit;
+        infoSz += maxSetLength + asnBit; /* SetSequence buffer needed        */
+        infoSz += 2 * MAX_ALGO_SZ;       /* buffer space for algorithm/curve */
+        infoSz += asnBit;
+        infoSz += maxSetLength;
+    }
+
+    if (inLen < wc_ecc_size(key) + infoSz) {
+        return BAD_FUNC_ARG;
+    }
+
+    return SetEccPublicKey(output, key, with_AlgCurve);
+}
+#endif /* HAVE_ECC && (WOLFSSL_CERT_GEN || WOLFSSL_KEY_GEN) */
+#if defined(WOLFSSL_CERT_GEN) && !defined(NO_RSA)
 
 static INLINE byte itob(int number)
 {

wolfcrypt/test/test.c

@@ -5001,6 +5001,7 @@ int rsa_test(void)
             free(tmp);
             return -5415;
         }
+
         fclose(pemFile);
         free(pem);
         free(derCert);
@@ -6486,6 +6487,25 @@ static int ecc_test_key_gen(WC_RNG* rng, int keySize)
         return -1029;
     }
 
+    /* test export of public key */
+    derSz = wc_EccPublicKeyToDer(&userA, der, FOURK_BUF, 1);
+    if (derSz <= 0) {
+       return -5516;
+    }
+#ifdef FREESCALE_MQX
+        keyFile = fopen("a:\\certs\\ecc-public-key.der", "wb");
+#else
+        keyFile = fopen("./ecc-public-key.der", "wb");
+#endif
+    if (!keyFile) {
+       return -5417;
+    }
+    ret = (int)fwrite(der, 1, derSz, keyFile);
+    fclose(keyFile);
+    if (ret != derSz) {
+       return -5418;
+    }
+
     wc_ecc_free(&userA);
 
     return 0;

wolfssl/wolfcrypt/asn_public.h

@@ -259,6 +259,10 @@ WOLFSSL_API int wc_SetCertificatePolicies(Cert *cert, const char **input);
     /* public key helper */
     WOLFSSL_API int wc_EccPublicKeyDecode(const byte*, word32*,
                                               ecc_key*, word32);
+    #if (defined(WOLFSSL_CERT_GEN) || defined(WOLFSSL_KEY_GEN))
+        WOLFSSL_API int wc_EccPublicKeyToDer(ecc_key*, byte* output,
+                                               word32 inLen, int with_AlgCurve);
+    #endif
 #endif
 
 /* DER encode signature */