B4X Requires Chilkat v11.0.0+

Duplicate PHP RSA Encryption

See more RSA Examples

Demonstrates how to duplicate the following PHP function. B4X

Dim success As Boolean = False

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

'  Duplicate the following PHP code:
'  
'     public function encryptRSA($plainText,$rsaMOD,$pubKEY){
'          $rsa  = new RSA();
'          $rsa->setEncryptionMode(RSA::ENCRYPTION_PKCS1);
'          $publicKey = [
'              'e' => new BigInteger($pubKEY,16),
'              'n' => new BigInteger($rsaMOD,16)
'          ];
'  		
'          $rsa->loadKey($publicKey);
'          $ciphertext = $rsa->encrypt($plainText);
'          return bin2hex($ciphertext);
'      }
'  
'      $plainText="key=abcdefghijkmnopq&iv=abcdefghijkmnopq&h=12345678&s=12345678"
'      $rsaMOD="F0946D8F05604809E24B8CFFD30349CEA9E5F4D320BFD9E9AA1B088863F02C43E7997D37A3E27B4F8F359F1744DB6B20A437067C0D325A80660D12FF56A57673"
'      $pubKEY="010001"

'  We have the RSA modulus in hex
Dim rsaMOD As String = "F0946D8F05604809E24B8CFFD30349CEA9E5F4D320BFD9E9AA1B088863F02C43E7997D37A3E27B4F8F359F1744DB6B20A437067C0D325A80660D12FF56A57673"

'  The RSA exponent in hex is "010001", which is 65537 in decimal.  It's typically the exponent that is always used.
Dim rsaEXP As String = "010001"

'  Get the RSA modulus and exponent in base64.
Dim bdMod As ChilkatBinData
bdMod.Initialize
Dim bdExp As ChilkatBinData
bdExp.Initialize
success = bdMod.AppendEncoded(rsaMOD, "hex")
success = bdExp.AppendEncoded(rsaEXP, "hex")

'  Build the XML representation of the RSA public key
Dim xml As ChilkatXml
xml.Initialize
xml.Tag = "RSAPublicKey"
xml.UpdateChildContent("Modulus", bdMod.GetEncoded("base64"))
xml.UpdateChildContent("Exponent", bdExp.GetEncoded("base64"))

'  Load the RSA public key into a Chilkat public key object.
Dim pubkey As ChilkatPublicKey
pubkey.Initialize
success = pubkey.LoadFromString(xml.GetXml)

'  Setup the RSA object for encryption and do it..
Dim rsa As ChilkatRsa
rsa.Initialize
rsa.VerboseLogging = True
success = rsa.UsePublicKey(pubkey)

'  Use PKCSv1.5 padding
rsa.PkcsPadding = True

'  Encrypt and return the string as hex.
rsa.EncodingMode = "hex"
Dim plainText As String = "key=abcdefghijkmnopq&iv=abcdefghijkmnopq&h=12345678&s=12345678"
Dim cipherText As String = rsa.EncryptStringENC(plainText, False)
If rsa.LastMethodSuccess = False Then
    Log(rsa.LastErrorText)
    Return
End If


'  Note: The PKCSv1_5 padding incorporates random bytes.  Therefore, the RSA encryption will produce different results each time -- all of which are valid 
'  and decrypt correctly to the same original text.
Log(cipherText)