private synchronized void ensureDigestInitializedInContext() {
        if (!digestInitializedInContext) {
            final NativeRef.EVP_MD_CTX ctxLocal = ctx;
            NativeCrypto.EVP_DigestInit_ex(ctxLocal, evp_md);
            digestInitializedInContext = true;
        }
    }
Creates a new OpenSSLMessageDigest instance for the given algorithm name.
common/src/main/java/org/conscrypt/OpenSSLMessageDigestJDK.java