Getting invalid base64 string when testing 3DS notification URLs

[patrickryan79]

On this page: here we find:

Sample Challenge Notification endpoint (server side)

For .NET, the value of "cres" that I'm getting back from the ACS is not a valid base64 string. I have no idea where to go from here. Is this documentation outdated?

[Externaluse]

We use a static method to decode it from base64 first;
while (input.Length % 4 != 0) { input += "="; } var data = Convert.FromBase64CharArray(input.ToCharArray(), 0, input.Length); return Encoding.UTF8.GetString(data); }

[SneyderOspinaChavarria]

You could use this to avoid the issue from base64

var a = Convert.FromBase64String(cres.Replace('-', '+').Replace('_', '/') + "=");
var challengeUrlResponseString = Encoding.UTF8.GetString(a);