(AutoIt) Duplicate PHP's openssl_encrypt and openssl_random_pseudo_bytes

Demonstrates how to duplicate PHP's openssl_encrypt function. (https://www.php.net/manual/en/function.openssl-encrypt.php)

For more information, see https://www.php.net/manual/en/function.openssl-encrypt.php

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

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

; Duplicates thw following PHP script:

; $text = "This is a test";
; $passphrase = "my password";
; $iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length("AES-256-CBC"));
; $crypted = base64_encode($iv.openssl_encrypt($text, "AES-256-CBC", $passphrase, OPENSSL_RAW_DATA, $iv));
; echo $crypted;

Local $bSuccess
$oCrypt = ObjCreate("Chilkat.Crypt2")

Local $sText = "This is a test"
Local $sPassphrase = "my password"

; AES is a block cipher.  The IV size for any block cipher is the size of the block, which is defined by the encryption algorithm. 
; For AES, the block size is always 16 bytes, regardless of key size (i.e. 128-bits, 192-bits, or 256-bits).
; Therefore, generate 16 random bytes for the IV.
$oCrypt.EncodingMode = "base64"
Local $sIvBase64 = $oCrypt.GenRandomBytesENC(16)

ConsoleWrite("Generated IV = " & $sIvBase64 & @CRLF)

; Because we're doing AES-256-CBC, the key length must be 256-bits (i.e. 32 bytes).
; Given that our passphrase is a us-ascii string that can be shorter or longer than 32-bytes, we need to 
; somehow transform the passphrase to a 32-byte secret key.  We need to know what openssl_encrypt does.
; Here's the answer from the openssl_encrypt documentation:
; 
; "If the passphrase is shorter than expected, it is silently padded with NUL characters; 
; if the passphrase is longer than expected, it is silently truncated."

; OK.... so let's pad or shorten to get a 32-byte key.
$oBdKey = ObjCreate("Chilkat.BinData")
$oBdKey.AppendString($sPassphrase,"utf-8")

Local $iSz = $oBdKey.NumBytes
If ($iSz > 32) Then
    $oBdKey.RemoveChunk(32,$iSz - 32)
Else
    $oBdKey.Clear()
    $oBdKey.AppendPadded($sPassphrase,"utf-8",False,32)
EndIf

; Setup for encryption.
$oCrypt.CryptAlgorithm = "aes"
$oCrypt.KeyLength = 256
$oCrypt.SetEncodedIV $sIvBase64,"base64"
$oCrypt.SetEncodedKey $oBdKey.GetEncoded("base64"),"base64"

; Encrypt and base64 encode.
Local $sCipherText64 = $oCrypt.EncryptStringENC($sText)

; The PHP code fragment above returns the base64 encoded bytes of the IV and the encrypted text.
; So let's do that..
$oBd = ObjCreate("Chilkat.BinData")
$oBd.AppendEncoded($sIvBase64,"base64")
$oBd.AppendEncoded($sCipherText64,"base64")
Local $sResult = $oBd.GetEncoded("base64")

ConsoleWrite("result = " & $sResult & @CRLF)

; Sample output:
; dN0vS1O0cWi5BbLAAY+NTf7bs3S27xzPf11RkG47sjs=

; Now let's decrypt from the output...

; Setup for decryption.
$oCrypt.CryptAlgorithm = "aes"
$oCrypt.KeyLength = 256
$oCrypt.SetEncodedKey $oBdKey.GetEncoded("base64"),"base64"

$oBdResult = ObjCreate("Chilkat.BinData")
$oBdResult.AppendEncoded($sResult,"base64")
$oCrypt.SetEncodedIV $oBdResult.GetEncodedChunk(0,16,"base64"),"base64"

; Remove the IV (first 16 bytes) from the result.
$oBdResult.RemoveChunk(0,16)
$bSuccess = $oCrypt.DecryptBd($oBdResult)
Local $sOriginalText = $oBdResult.GetString("utf-8")

ConsoleWrite("original text = " & $sOriginalText & @CRLF)