private static byte[] readSecurityBuffer(final byte[] src, final int index) {
        final int length = readUShort(src, index);
        final int offset = readULong(src, index + 4);
        if (src.length < offset + length) {
            return new byte[length];
        }
        final byte[] buffer = new byte[length];
        System.arraycopy(src, offset, buffer, 0, length);
        return buffer;
    }
Creates the type 3 message using the given server nonce. The type 3
message includes all the information for authentication, host, domain,
username and the result of encrypting the nonce sent by the server using
the user's password as the key.

@param user
           The user name. This should not include the domain name.
@param password
           The password.
@param host
           The host that is originating the authentication request.
@param domain
           The domain to authenticate within.
@param nonce
           the 8 byte array the server sent.
@return The type 3 message.
httpclient5/src/main/java/org/apache/hc/client5/http/impl/auth/NTLMEngineImpl.java