@Override
        protected void initContext(byte[] keyBytes) {
            NativeRef.CMAC_CTX ctxLocal = new NativeRef.CMAC_CTX(NativeCrypto.CMAC_CTX_new());
            NativeCrypto.CMAC_Init(ctxLocal, keyBytes);
            this.ctx = ctxLocal;
        }
Holds the EVP_MD for the hashing algorithm, e.g.
EVP_get_digestbyname("sha1");
common/src/main/java/org/conscrypt/OpenSSLMac.java