PowerShell Requires Chilkat v11.6.0+

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.

Background. A pepper is a secret value held by the application and not stored with the hash, so a stolen hash database cannot be attacked without it. The encoding members control how the salt, secret, and ad text are interpreted as bytes (base64 by default; utf-8 uses the characters themselves). maxMemoryKb is a guard against an unreasonable memory cost.

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Add-Type -Path "C:\chilkat\ChilkatDotNet47-x64\ChilkatDotNet47.dll"

$success = $false

$crypt = New-Object Chilkat.Crypt2

#  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 = New-Object Chilkat.JsonObject

#  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 = New-Object Chilkat.BinData
$success = $crypt.Argon2DeriveKey($password,$json.Emit(),$bdKey)
if ($success -eq $false) {
    $($crypt.LastErrorText)
    exit
}

$keyHex = $bdKey.GetEncoded("hex")
if ($bdKey.LastMethodSuccess -eq $false) {
    $($bdKey.LastErrorText)
    exit
}

$("Derived key: " + $keyHex)