Xojo Plugin

Manually Duplicate SetSecretKeyViaPassword

Demonstrates how to duplicate the password string to binary secret key computation of SetSecretKeyViaPassword.

This is a cryptographically weak way of generating a secret key from a password. The SetSecretKeyViaPassword method is deprecated and should not be used.

Xojo Plugin

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Dim crypt As New Chilkat.Crypt2

// The password string is transformed to a binary secret key by computing the 
// MD5 digest (of the utf-8 password) to obtain 16 bytes.  
// If the KeyLength is greater than 16 bytes, then the MD5 digest of the Base64 encoding 
// of the utf-8 password is added.  A max of 32 bytes of key material is generated, and 
// this is truncated to the actual KeyLength required.

crypt.CryptAlgorithm = "aes"
crypt.KeyLength = 256

Dim password As String
password = "this is my password"
crypt.SetSecretKeyViaPassword password

// Examine the resulting SecretKey in hex:
System.DebugLog("Computed Secret Key = " + crypt.GetEncodedKey("hex"))

// Now perform the same computation manually:
Dim sb As New Chilkat.StringBuilder

crypt.HashAlgorithm = "md5"
crypt.Charset = "utf-8"
crypt.EncodingMode = "hex"
Dim success As Boolean
success = sb.Append(crypt.HashStringENC(password))

Dim passwordBase64 As String
passwordBase64 = crypt.EncodeString(password,"utf-8","base64")
success = sb.Append(crypt.HashStringENC(passwordBase64))

System.DebugLog("Manually Computed = " + sb.GetAsString())

// The output is:
// Computed Secret Key = 210D53992DFF432EC1B1A9698AF9DA16C7E90518F90E24828F78EC9E0A413B36
// Manually Computed = 210D53992DFF432EC1B1A9698AF9DA16C7E90518F90E24828F78EC9E0A413B36