crypto: Add evp hashing function.

src/libcrypto.c

@@ -97,6 +97,34 @@ void sha1(unsigned char *digest, int len, unsigned char *hash) {
   SHA1(digest, len, hash);
 }
 
+#ifdef HAVE_OPENSSL_ECC
+static const EVP_MD *nid_to_evpmd(int nid)
+{
+    switch (nid) {
+        case NID_X9_62_prime256v1:
+            return EVP_sha256();
+        case NID_secp384r1:
+            return EVP_sha384();
+        case NID_secp521r1:
+            return EVP_sha512();
+        default:
+            return NULL;
+    }
+
+    return NULL;
+}
+
+void evp(int nid, unsigned char *digest, int len, unsigned char *hash, unsigned int *hlen)
+{
+    const EVP_MD *evp_md = nid_to_evpmd(nid);
+    EVP_MD_CTX md;
+
+    EVP_DigestInit(&md, evp_md);
+    EVP_DigestUpdate(&md, digest, len);
+    EVP_DigestFinal(&md, hash, hlen);
+}
+#endif
+
 SHA256CTX sha256_init(void){
   SHA256CTX c = malloc(sizeof(*c));
   if (c == NULL) {