Comments on: Calculating hash values with NAV2013

By: Lots of new goodies hidden inside NAV2018 | Hougaard.com – Applied Hacking

Fri, 26 Jan 2018 23:11:55 +0000

[…] needed to hash some passwords in NAV. I turned to my blog (via a trip to Google) and found my old article on the subject, […]

By: hougaard

hougaard — Tue, 04 Aug 2015 16:22:47 +0000

In reply to Roddy.

You cannot use SHA256 for HMACSHA256 – see http://security.stackexchange.com/questions/79577/whats-the-difference-between-hmac-sha256key-data-and-sha256key-data

You much recreate this C# example from Amazon in C/AL
static byte[] HmacSHA256(String data, byte[] key) { String algorithm = "HmacSHA256"; KeyedHashAlgorithm kha = KeyedHashAlgorithm.Create(algorithm); kha.Key = key;


    return kha.ComputeHash(Encoding.UTF8.GetBytes(data));

}
static byte[] getSignatureKey(String key, String dateStamp, String regionName, String serviceName)

{

    byte[] kSecret = Encoding.UTF8.GetBytes(("AWS4" + key).ToCharArray());

    byte[] kDate = HmacSHA256(dateStamp, kSecret);

    byte[] kRegion = HmacSHA256(regionName, kDate);

    byte[] kService = HmacSHA256(serviceName, kRegion);

    byte[] kSigning = HmacSHA256("aws4_request", kService);

return kSigning; }

By: Roddy

Roddy — Tue, 04 Aug 2015 15:47:50 +0000

Hi, thanks for the SHA256 code. I think I may be misusing it, I’m trying to create a signature for Amazon Web Services, (http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html) as below (first step). Any help would be greatly appreciated. Thanks Roddy

Test Input
key = ‘wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY’
dateStamp = ‘20120215’

Expected Output
kDate = ‘969fbb94feb542b71ede6f87fe4d5fa29c789342b0f407474670f0c2489e0a0d’

Actual Output
kDate = ‘8583c661110d4c95a37df70fd6f70d92fd18418f306c9f8d54582a2c354acad4”

Sample Psuedo code from AWS
kDate = HMAC(“AWS4” + key, dateStamp) //UTF-8

My use of your library
CLEAR(SHA256Lib);
SHA256Lib.InitSHA256;
SHA256Lib.AddString(AsciiAnsiLib.Ansi2Ascii(‘AWS4’ + key));
SHA256Lib.AddLF;
SHA256Lib.AddString(DateStamp);
kDate := SHA256Lib.CalculateSHA256;