ABAP string to SHA256 different to SAPUI5/Javascript

[former_member595185]

Hi all,

Currently on my SAPUI5 project, I am creating a HMAC encoded string with this line of code;

var secretKey = CryptoJS.enc.Hex.parse('SECRETKEY'); //USING THE CRYPTOJS LIBRARY!
var hash = CryptoJS.HmacSHA256('abc', secretKey);
hashInBase64 = CryptoJS.enc.Base64.stringify(hash);

I am using the CryptoJS library to execute this code in UI5.

However the problem is that I am receiving the wrong HMAC encoded string when I want to do the same in ABAP. After testing a few times, it seems like the encoding (in abap) is wrong before the HMAC is calculated.

Is there a function module that does 'CryptoJS.enc.Hex.parse()' - after googling what it does it interprets the parameter as encoded and converts it into a word array.

DATA:
      lv_sign_key_x                TYPE xstring,
      lv_hmac_result               TYPE string.

DATA(lv_binary_secret) = cl_abap_hmac=>string_to_xstring('SECRETKEY').

    cl_abap_hmac=>calculate_hmac_for_char(
      EXPORTING
        if_algorithm           = 'SHA256'           "Hash Algorithm
        if_key                 = lv_binary_secret   "HMAC Key
        if_data                = 'abc'   "Data
      IMPORTING
        ef_hmacb64string       = lv_hmac_result  "HMAC value as base64-encoded string
    ).

Thank you in advance.

[Former Member · Accepted solution]

In this case are you sure about this line in your JS code?

var secretKey = CryptoJS.enc.Hex.parse('SECRETKEY');//USING THE CRYPTOJS LIBRARY!

Method CryptoJS.enc.Hex.parse parses the already Hex-encoded string and converts it into string.

So if you want string from Hex, you use it and if you want hex-encoding from string then you use Hex.stringify.

var words = CryptoJS.enc.Hex.parse("48656c6c6f2c20576f726c6421");
var hex = CryptoJS.enc.Hex.stringify(words);

So I am a bit confused here.

What is a value returned by this code? I assume null.

var secretKey = CryptoJS.enc.Hex.parse('SECRETKEY');//USING THE CRYPTOJS LIBRARY!

Check CryptoJS docs:

https://cryptojs.gitbook.io/docs/

Viktor

[former_member595185 · Accepted solution]

Sorry if it may seem confusing to you. not sure if 'SECRETKEY' is confusing you, I only used that word as I don't want to share the actual key I'll use '48656c6c6f2c20576f726c6421' as the key I am parsing for now.. The code in Javascript is perfectly correct and I need the ABAP to perform the same way/same results.

In Javascript I am parsing the hex which comes back with a word array using this line of code

var words = CryptoJS.enc.Hex.parse("48656c6c6f2c20576f726c6421");

1. words: Array(4)
   1. 0: 1214606444
   2. 1: 1865162839
   3. 2: 1869769828
   4. 3: 553648128

I then use the word array to be placed in var hash = CryptoJS.HmacSHA256('abc', wordArray); and then converted into Base64

This is all correct and the documentation is in this page - https://docs.adyen.com/classic-integration/hosted-payment-pages/hmac-signature-calculation/ which is what I have done in Javascript and have tested that it works. The javascript is completely fine. I just need a solution in ABAP.

However, I want to do the same thing in ABAP... The ABAP is returning a completely different encode

DATA(lv_binary_secret)= cl_abap_hmac=>string_to_xstring('48656c6c6f2c20576f726c6421').

Relating to the link I have provided above on step 4, Do you know how to hex encode my key in ABAP?

[Former Member · Accepted solution]

In this case the following should work:

    data lv_binary_secret type xstring.
    data lv_string type string value '48656c6c6f2c20576f726c6421'.
    translate lv_string to upper case.
    lv_binary_secret = lv_string.


    cl_abap_hmac=>calculate_hmac_for_char(
      EXPORTING
        if_algorithm           = 'SHA256'           "Hash Algorithm
        if_key                 = lv_binary_secret   "HMAC Key
        if_data                = 'abc'   "Data
      IMPORTING
        ef_hmacb64string       = data(lv_hmac_result)  "HMAC value as base64-encoded string
    ).

[former_member595185 · Accepted solution]

Working as intended. Thanks a lot Viktor.