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.

#include <CkCrypt2.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    CkCrypt2 crypt;

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

    const char *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.
    CkJsonObject json;
    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) {
        std::cout << "The password is verified." << "\r\n";
    }
    else {
        if (verifyResult == 0) {
            std::cout << "The password does not match." << "\r\n";
        }
        else {
            std::cout << "The verification could not be performed: " << crypt.lastErrorText() << "\r\n";
        }

    }
    }