How do I use the OpenSSL.Net C# wrapper to encrypt a string with AES?

Question

I am trying to send some encrypted data from my SharePoint site to my company's PeopleSoft site. The PeopleSoft folks insist that I have to use the OpenSSL library for my encryption. I have downloaded and installed the OpenSSL.Net project from SourceForge.

For my purposes, I need to simply encrypt a string with AES. I know how to do this with the System.Security.Cryptography library, but am having a very difficult time translating this to the OpenSSL.Net side. Very frustrating, since I can see everything that I think I need in Intellisense!

Does anybody have an example of performing string encryption/decryption with AES using the OpenSSL.Net wrapper?

Thanks!

-Nick

Answer 1

Here is the sample which works for me. I simplified it by using copy-paste but should not matter.

I'm using text password due to compatibility with JS library but open SSL itself supports direct usage of byte[] Key and IV so it's up to you what to use.

In order to switch binary data into the string just use

Encoding.UTF8.GetBytes() and Encoding.UTF8.GetString()

to convert back and forth.

    public Byte[] Encrypt(Byte[] data, String password)
    {
        //Just random 8 bytes for salt
        var salt = new Byte[] {1, 2, 3, 4, 5, 6, 7, 8};

        using (var cc = new CipherContext(Cipher.AES_256_CBC))
        {
            //Constructing key and init vector from string password
            byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
            byte[] iv;
            byte[] key = cc.BytesToKey(MessageDigest.MD5, salt, passwordBytes, 1, out iv);

            var memoryStream = new MemoryStream();

            //Performing encryption thru unmanaged wrapper
            var aesData = cc.Crypt(data, key, iv, true);

            //Append salt so final data will look Salted___SALT|RESTOFTHEDATA
            memoryStream.Write(Encoding.UTF8.GetBytes("Salted__"), 0, 8);
            memoryStream.Write(salt, 0, 8);
            memoryStream.Write(aesData, 0, aesData.Length);

            return memoryStream.ToArray();
        }
    }

    public Byte[] Decrypt(String password, Byte[] encryptedData)
    {
        byte[] salt = null;
        //extracting salt if presented
        if (encryptedData.Length > 16)
        {
            if (Encoding.UTF8.GetString(encryptedData).StartsWith("Salted__"))
            {
                salt = new Byte[8];
                Buffer.BlockCopy(encryptedData, 8, salt, 0, 8);
            }
        }

        //Removing salt from the original array
        int aesDataLength = encryptedData.Length - 16;
        byte[] aesData = new byte[aesDataLength];
        Buffer.BlockCopy(encryptedData, 16, aesData, 0, aesDataLength);


        using (var cc = new CipherContext(Cipher.AES_256_CBC))
        {
            //Constructing key and init vector from string password and salt
            byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
            byte[] iv;
            byte[] key = cc.BytesToKey(MessageDigest.MD5, salt, passwordBytes, 1, out iv);

            //Decrypting
            return cc.Decrypt(aesData, key, iv, 0);

        }


    }