Using xmlsq and CryptoSys PKI to decrypt XMLENC documents

Here is an example C# program using xmlsq and CryptoSys PKI to decrypt some sample XMLENC documents.

The code uses xmlsq to query the XMLENC documents for the relevant information, then uses the CryptoSys PKI cryptographic functions to decrypt the cipher value.

This is a C# Console Application. In your project, add references to the .NET library files diXmlsqNet.dll and diCrSysPKINet.dll (you should find these in C:\Program Files (x86)\xmlsq\DotNet and C:\Program Files (x86)\CryptoSysPKI\DotNet).

Example using xmlsq command-line

FILE: encrypt-data-aes192-cbc-kw-aes256.xml

<?xml version="1.0" encoding="UTF-8"?>
<EncryptedData xmlns="http://www.w3.org/2001/04/xmlenc#" MimeType="text/plain">
  <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes192-cbc" />
  <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
    <EncryptedKey xmlns="http://www.w3.org/2001/04/xmlenc#">
      <EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#kw-aes256" />
      <KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
        <KeyName>jed</KeyName>
      </KeyInfo>
      <CipherData>
        <CipherValue>
          4AAgyi3M7xNdBimbQZKdGJLn3/cS4Yv8QKuA01+gUnY=
        </CipherValue>
      </CipherData>
    </EncryptedKey>
  </KeyInfo>
  <CipherData>
    <CipherValue>
      50lv94d/DFJirJXYOUXaBlrO+7gIXpx8cqH+G2xvE4mueoIxmGs8RH7FBXwjuMgf
    </CipherValue>
  </CipherData>
</EncryptedData>

:: How many EncryptedKeys? We expect at least one or we quit.
> xmlsq --count //EncryptedKey encrypt-data-aes192-cbc-kw-aes256.xml
1

:: Get encryption algorithm used for encrypted key-encryption key
> xmlsq "//EncryptedKey/EncryptionMethod/@Algorithm" encrypt-data-aes192-cbc-kw-aes256.xml
http://www.w3.org/2001/04/xmlenc#kw-aes256

:: Get KeyName for intended recipient
> xmlsq "//EncryptedKey/KeyInfo/KeyName" encrypt-data-aes192-cbc-kw-aes256.xml
jed

:: Get encrypted key value
> xmlsq --trim "//EncryptedKey/CipherData/CipherValue" encrypt-data-aes192-cbc-kw-aes256.xml
4AAgyi3M7xNdBimbQZKdGJLn3/cS4Yv8QKuA01+gUnY=

:: Use jed's secret AES-256 key to decrypt and get the content-encryption key (CEK)...

:: Get encryption algorithm used to encrypt the data
> xmlsq "//EncryptedData/EncryptionMethod/@Algorithm" encrypt-data-aes192-cbc-kw-aes256.xml
http://www.w3.org/2001/04/xmlenc#aes192-cbc

:: Get encrypted data
> xmlsq --trim "//EncryptedData/CipherData/CipherValue" encrypt-data-aes192-cbc-kw-aes256.xml
50lv94d/DFJirJXYOUXaBlrO+7gIXpx8cqH+G2xvE4mueoIxmGs8RH7FBXwjuMgf

:: Use the CEK to decrypt the content...

See the C# code above to see how to do the same using the .NET interface to xmlsq

Using xmlsq and CryptoSys PKI to decrypt XMLENC documents

Example using xmlsq command-line

Contact us