Decrypt data from PHP in Xojo

Add-Ons
1

Recently we discussed how to encrypt something in PHP and then decrypt in Xojo. Check out the CipherMBS class in our plugin, which corresponds to openssl_encrypt/openssl_decrypt functions in PHP.

Here is a sample script in PHP to generate a random initial vector and a random key. Then encrypt some text with openssl using blowfish algorithm and CBC as block mode:

$cipher = 'bf-cbc';
$iv_size = openssl_cipher_iv_length($cipher);
$key_size = 20;
$iv = random_bytes($iv_size);
$key = random_bytes($key_size);

$encrypted = openssl_encrypt('Hello World. Just a test here!', $cipher, $key, OPENSSL_RAW_DATA, $iv);

print "iv: ".base64_encode($iv)."\n";
print "key: ".base64_encode($key)."\n";
print "encrypted: ".base64_encode($encrypted)."\n";

For such an encryption, you need to replicate on both sides the same settings:

  • Identical key data. May need you to hash key first.
  • Identical initial vector
  • Identical setting for padding of data to match required block size.
  • Identical handling for keys with too small size. e.g. fill up with zero bytes.

You can run the PHP script above and copy the values into the Xojo code below:

Var Cipher As CipherMBS = CipherMBS.bf_cbc Call Cipher.EncryptInit(DecodeBase64("79aMfVRxPw0="), DecodeBase64("2peenIoTK1k=")) Var Decrypted As MemoryBlock = Cipher.ProcessMemory(DecodeBase64("JBvDgbeC6vECJGiRnh27GQ==")) + Cipher.FinalizeAsMemory() Print Decrypted

If everything works fine, the result in the unencrypted text as in the PHP script.

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2

Hi,
CipherMBS class from the MBS Xojo Encryption Plugin.


Dim cipher As New CipherMBS
cipher.Mode = CipherMBS.bf_cbc

Dim iv As MemoryBlock = DecodeBase64("79aMfVRxPw0=")
Dim key As MemoryBlock = DecodeBase64("2peenIoTK1k=")
cipher.SetKey(key)

Dim encryptedData As MemoryBlock = DecodeBase64("JBvDgbeC6vECJGiRnh27GQ==")

Dim decryptedData As MemoryBlock
If cipher.DecryptInit(iv) Then
  decryptedData = cipher.ProcessMemory(encryptedData)
  decryptedData = decryptedData + cipher.FinalizeAsMemory()
  
   Convert the decrypted data to a string
  Dim decryptedText As String = decryptedData.StringValue(0, decryptedData.Size, Encodings.UTF8)
  
  MsgBox decryptedText
End If

Make sure MBS Xojo Encryption Plugin installed and properly configured in your Xojo project. Replace the values of the iv, key , and encryptedData variables with the corresponding values generated by the PHP script.
The decrypted data will be stored in the decryptedData MemoryBlock, and you can convert it to a string using the appropriate encoding (in this example, UTF-8).
Now you can display the decrypted text using a MsgBox or perform any other desired processing.

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