Hi all

I’m banging my head against the wall on this.. I have to port a bit of Java code over to Elixir/erlang and can’t seem to get this working.. I mean I can get my code to output base64 encoded strings but the server is rejecting them as invalid.

This is the function in question:

    private static String generateMacSignature(final String payload, final String resourceURI, final String host,
					       final String port, final String macId, final String key, final String httpMethod) {
    	String signature = null;
    	try {
	    String timestamp = Long.toString(System.currentTimeMillis()).trim();
	    String nonce = UUID.randomUUID().toString().trim();
	    String bodyHash = encode(payload, key);
	    // Create MAC input string
	    String macInput = timestamp + "\n" + nonce + "\n" + httpMethod + "\n" + resourceURI + "\n" + host + "\n"
		+ port + "\n" + bodyHash + "\n";
	    String encodedMacInput = encode(macInput, key);
	    String macRequestAuthFmt = "MAC id={0},ts={1},nonce={2},bodyhash={4},mac={3}";
	    String[] authHeaderInputs = new String[]{"\"" + macId + "\"", "\"" + timestamp + "\"", "\"" + nonce + "\"",
						     "\"" + encodedMacInput + "\"", "\"" + bodyHash + "\""};
	    signature = MessageFormat.format(macRequestAuthFmt, authHeaderInputs);
    	} catch (Exception e) {
	    System.err.println("Exception while generating MAC Signature: " + e.getMessage());
    	}
    	return signature;
    }

    private static String encode(String data, String key) throws Exception {
    	String encodedData = null;
    	try {
	    // get an HmacSHA256 signing- key from the raw key bytes
	    SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(), "HmacSHA256");
	    // get an HmacSHA256Mac instance and initialize with the signing key
	    Mac mac = Mac.getInstance("HmacSHA256");
	    mac.init(signingKey);
	    // compute the hmac on input data bytes
	    byte[] rawHmac = mac.doFinal(data.getBytes());
	    // base64-encode the hmac
	    encodedData = new String(Base64.encodeBase64(rawHmac)).replace("\r\n", StringUtils.EMPTY);
    	} catch (Exception e) {
	    throw e;
    	}
    	return encodedData;
    }

I’ve basically tried a few different variants of this based on some posts I’ve seen here and SO as well as asking GPT4 and haven’t been able to get the server integration to work.

Here’s my basic function but I’m not completely sure how those Java libraries work or what they’re doing that’s different.

  defp encode(data, secret) do
    :crypto.mac(:hmac, :sha256, secret, data) |> Base.encode64
  end

Thanks for any assistance!