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.

let crypt = chilkat::Crypt2::new();

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

let phc_hash = "$argon2id$v=19$m=131072,t=4,p=2$c29tZXJhbmRvbXNhbHQ$3fJ7v1qKcVJ0lHqXjBQZ8mYm3sNTfSPRt0bqDl9kEyM".to_string();

// 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.
let json = chilkat::JsonObject::new();
let _ = json.update_string("secret", "application-wide-pepper");
let _ = json.update_string("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.
let _ = json.update_int("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.
let verify_result = crypt.argon2_verify_password(&password, &json.emit().unwrap_or_default(), &phc_hash);
if verify_result == 1 {
    println!("The password is verified.");
} else {
    if verify_result == 0 {
        println!("The password does not match.");
    } else {
        println!("The verification could not be performed: {}", crypt.last_error_text());
    }

}