Argon2 Key Derivation with a Secret (Pepper), AD, and Encodings

Demonstrates the optional Argon2 options for Crypt2.Argon2DeriveKey: secret (a pepper), ad (associated data), the encoding member and its per-member overrides saltEncoding/secretEncoding/adEncoding, passwordCharset, and maxMemoryKb.

require 'chilkat'

success = false

crypt = Chilkat::CkCrypt2.new()

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

#  Build the Argon2 options JSON, this time using the optional secret, ad, and encoding members.
#    secret         the RFC 9106 secret value K, often called a "pepper": a key held by the
#                   application and NOT stored with the hash, so a stolen hash database cannot be
#                   attacked without it.
#    ad             optional associated data X: additional non-secret data bound into the derivation.
#    encoding       how salt, secret, and ad are encoded (default base64).  Per-member overrides are
#                   saltEncoding, secretEncoding, and adEncoding.
#    passwordCharset  the charset the password is converted to before use (default utf-8).
#    maxMemoryKb    a guard (not an Argon2 parameter) refusing to allocate more than this many KB;
#                   default 2097152 (2 GB).
json = Chilkat::CkJsonObject.new()

#  The salt is provided here as hex, overriding the default base64 for just this member.
json.UpdateString("salt","0102030405060708090a0b0c0d0e0f10")
json.UpdateString("saltEncoding","hex")

#  The pepper is supplied as UTF-8 text (its own characters are the bytes).
json.UpdateString("secret","application-wide-pepper")
json.UpdateString("secretEncoding","utf-8")

#  Associated data, supplied as UTF-8 text.
json.UpdateString("ad","user-id-42")
json.UpdateString("adEncoding","utf-8")

json.UpdateString("passwordCharset","utf-8")
json.UpdateInt("maxMemoryKb",1048576)
json.UpdateInt("keyLen",32)

bdKey = Chilkat::CkBinData.new()
success = crypt.Argon2DeriveKey(password,json.emit(),bdKey)
if (success == false)
    print crypt.lastErrorText() + "\n";
    exit
end

keyHex = bdKey.getEncoded("hex")
if (bdKey.get_LastMethodSuccess() == false)
    print bdKey.lastErrorText() + "\n";
    exit
end

print "Derived key: " + keyHex + "\n";