Verify an Argon2 Password with a Secret and Memory Guard

Demonstrates Crypt2.Argon2VerifyPassword when the hash was created with a secret (pepper) or ad, and the use of maxMemoryKb to guard against untrusted hash strings.

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

//  The password should come from a secure source rather than being hard-coded.
string password = "correct horse battery staple";

string phcHash = "$argon2id$v=19$m=131072,t=4,p=2$c29tZXJhbmRvbXNhbHQ$3fJ7v1qKcVJ0lHqXjBQZ8mYm3sNTfSPRt0bqDl9kEyM";

//  When the hash was created with a secret (pepper) or ad, the same values must be supplied to verify.
//  Only the secret, ad, encoding, passwordCharset, and maxMemoryKb members of the options are used;
//  everything else is ignored.
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.UpdateString("secret","application-wide-pepper");
json.UpdateString("secretEncoding","utf-8");

//  maxMemoryKb guards against a hash from an untrusted source claiming an enormous memory cost.  The
//  memory cost is taken from the hash string, so this limit is checked before any memory is allocated.
//  It defaults to 2 GB.
json.UpdateInt("maxMemoryKb",262144);

//  Argon2VerifyPassword returns 1 if the password matched, 0 if it did not match, and -1 if the
//  verification could not be performed.  Always test for a match with == 1.
int verifyResult = crypt.Argon2VerifyPassword(password,json.Emit(),phcHash);
if (verifyResult == 1) {
    Debug.WriteLine("The password is verified.");
}
else {
    if (verifyResult == 0) {
        Debug.WriteLine("The password does not match.");
    }
    else {
        Debug.WriteLine("The verification could not be performed: " + crypt.LastErrorText);
    }

}