C# Shiznit - Library Encrypt and Decrypt Methods Using TripleDES and MD5

Library Encrypt and Decrypt Methods Using TripleDES and MD5

posted on Monday, January 09, 2006 by bobby @ 7:01 am

13 comments

For you encrypting enjoyment:
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public static string Encrypt(string toEncrypt, string key, bool useHashing)
{
    byte[] keyArray;
    byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

    if(useHashing)
    {
        MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
        keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
    }
    else
        keyArray = UTF8Encoding.UTF8.GetBytes(key);

    TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
    tdes.Key = keyArray;
    tdes.Mode = CipherMode.ECB;
    tdes.Padding = PaddingMode.PKCS7;

    ICryptoTransform cTransform = tdes.CreateEncryptor();
    byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

    return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}

And in case you ever want to decrypt that string you just encrypted:
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public static string Decrypt(string toDecrypt, string key, bool useHashing)
{
    byte[] keyArray;
    byte[] toEncryptArray = Convert.FromBase64String(toDecrypt);

    if(useHashing)
    {
        MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
        keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
    }
    else
        keyArray = UTF8Encoding.UTF8.GetBytes(key);

    TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
    tdes.Key = keyArray;
    tdes.Mode = CipherMode.ECB;
    tdes.Padding = PaddingMode.PKCS7;

    ICryptoTransform cTransform = tdes.CreateDecryptor();
    byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);

    return UTF8Encoding.UTF8.GetString(resultArray);
}

$secret_key = "THESECRETKEYFOR3DESABCDEF"; $iv = base64_decode("5Fl6lc4xjwA="); $crypttext = mcrypt_encrypt(MCRYPT_3DES, $secret_key, $ID, MCRYPT_MODE_CBC, $iv); $id_encriptado = urlencode(base64_encode($crypttext));

try{ TripleDESCryptoServiceProvider tripleDESProvider = newTripleDESCryptoServiceProvider(); tripleDESProvider.Key = Encoding.UTF8.GetBytes("THESECRETKEYFOR3DESABCDEF"); tripleDESProvider.IV = Convert.FromBase64String( "5Fl6lc4xjwA="); tripleDESProvider.Mode = CipherMode.CBC; tripleDESProvider.Padding = PaddingMode.Zeros;//THE SUPERNATURAL STUFF ICryptoTransform ict = tripleDESProvider.CreateDecryptor(); byte [] fromBase64 = Convert.FromBase64String(textToDecrypt); byte [] decryptedData = ict.TransformFinalBlock( fromBase64 ,0, fromBase64.Length ); return Encoding.ASCII.GetString(decryptedData); } catch(Exception s){ Console.WriteLine(s.ToString()); } return "";

CommentsComments

This is not bad, but it is missing one key piece. Both MD5CryptoServiceProvider and
TripleDESCryptoServiceProvider are managed wrappers around unmanaged resources. You need to use Clear (which in turn calls Dispose) or Dispose directly, ideally in a finally block of a try/catch.

Greeting, Bobby! Nice code! Thanks for it.

yes.. Good Stuff. But for the sake of best practise u needed to do some extra lines. like instead of

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keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(key));
write: byteCode=UTF8Encoding.UTF8.GetBytes(key);
keyArray = hashmd5.ComputeHash(byteCode);

and finall a serious mistake not to be done. DONOT forget to clear/flush the en/de-crypton
like :::: hashmd5.clear();
and tdes.clear();

any way nice and helpful stuff

Why is it necessary to put the bytes into another, seperate variable, which will just be hashed into the key array on the next line? What is the benefit?

Cheers

i just mentioned abt the best practices of the industry....
you may ommit so many code... for example lets say you wrote.. in encryption and decryption too..

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TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
tdes.Key = keyArray;
tdes.Mode = CipherMode.ECB;
tdes.Padding = PaddingMode.PKCS7;

all these lines can be converted to one line code IF YOU PASS all these as constructor params....
The reason i am saying this is You should practise the BEST approach and go deep and know more what is going under the hood.....
ANYWAY it was nice code

can someone decrypt a PKCS7 string for me?

very very usefully, great!!!

It is very very userful. Thanks.

Thank you for posting this, it was quite helpful. I was working through using the AesCryptoServiceProvider in VS 2008 (.Net 3.x), and was having a hell of a problem. MSDN didn't have what I needed, and trying to implement their workings of DES (which would be a logical precursor and process base for AES...but what the heck do I know?), and having no luck.

So now for your info, this general scheme works for AES as well!

Nice...As always, the BEST practice is the practice that WORKS...this works very well.

ok

enter enter

fantastic. exactly what we needed

Hi, just a comment for a related topic.
if you need to crypt in PHP and decrypt in C# using 3DES, you can do something like that:

The url_encode and base64_encode is just for web compatibility issues.

Then, you can decrypt the generated strings in C# using the following code:

In order to prevent problems with the IV Key it's better to store it in base64.

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