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.

import chilkat2

crypt = chilkat2.Crypt2()

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

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.
json = chilkat2.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.
verifyResult = crypt.Argon2VerifyPassword(password,json.Emit(),phcHash)
if (verifyResult == 1):
    print("The password is verified.")
else:
    if (verifyResult == 0):
        print("The password does not match.")
    else:
        print("The verification could not be performed: " + crypt.LastErrorText)