Convert C# decryption to Python PyDes
I'm having trouble converting code from C# to Python. Over at Martijn's C# Blog is an excellent program for encrypt/decrypt [enclosed below] but I can't get it to convert directly to the python version pyDes [sample below]
public static string DecryptString(string Message, string Passphrase)
{
byte[] Results;
System.Text.UTF8Encoding UTF8 = new System.Text.UTF8Encoding();
// Step 1. We hash the passphrase using MD5
// We use the MD5 hash generator as the result is a 128 bit byte array
// which is a valid length for the TripleDES encoder we use below
MD5CryptoServiceProvider HashProvider = new MD5CryptoServiceProvider();
byte[] TDESKey = HashProvider.ComputeHash(UTF8.GetBytes(Passphrase));
// Step 2. Create a new TripleDESCryptoServiceProvider object
TripleDESCryptoServiceProvider TDESAlgorithm = new TripleDESCryptoServiceProvider();
// Step 3. Setup the decoder
TDESAlgorithm.Key = TDESKey;
TDESAlgorithm.Mode = CipherMode.ECB;
TDESAlgorithm.Padding = PaddingMode.PKCS7;
// Step 4. Convert the input string to a byte[]
byte[] DataToDecrypt = Convert.FromBase64String(Message);
// Step 5. Attempt to decrypt the string
try
{
ICryptoTransform Decryptor = TDESAlgorithm.CreateDecryptor();
Results = Decryptor.TransformFinalBlock(DataToDecrypt, 0, DataToDecrypt.Length);
}
finally
{
// Clear the TripleDes and Hashprovider services of any sensitive information
开发者_StackOverflowTDESAlgorithm.Clear();
HashProvider.Clear();
}
// Step 6. Return the decrypted string in UTF8 format
return UTF8.GetString( Results );
}
PyDES:
from pyDes import *
data = "Please encrypt my data"
k = des("DESCRYPT", ECB, "\0\0\0\0\0\0\0\0", pad=None, padmode=PAD_PKCS5)
d = k.encrypt(data)
print "Encrypted: %r" % d
print "Decrypted: %r" % k.decrypt(d)
assert k.decrypt(d, padmode=PAD_PKCS5) == dat
I modified the original pyDes to use ECB instead of CBC. None of the strings match and I'm at the end of my rope. Please help! Thanks
Never mind --- figured it out.
If you change this line in pyDes
print "Encrypted: %r" % d
to
print "Encrypted: %r" % d.encode('base64')
then the code matches up exactly.
To compare, run the original code from Martijn's site: [Output]
Message: This world is round, not flat, don't believe them! Password: secret Encrypted string: pafHnI124lxzCr+93COqxfgOTan8x9oPzX4R/PDYkBnrjufk0/7mesG5tmS2AU Pxna3z0jY+7II= Decrypted string: This world is round, not flat, don't believe them!
And here is the modified code from pyDes -- you need to pad the password with md5Hash
import md5
from pyDes import *
Msg = "This world is round, not flat, don't believe them!"
Password = "secret"
m=md5.new()
m.update(Password)
k = triple_des(m.digest() , ECB,padmode=PAD_PKCS5)
d = k.encrypt(Msg)
print "Encrypted: %r" % d.encode('base64')
print "Decrypted: %r" % k.decrypt(d)
assert k.decrypt(d, padmode=PAD_PKCS5) == Msg
with the output:
Encrypted: 'pafHnI124lxzCr+93COqxfgOTan8x9oPzX4R/PDYkBnrjufk0/7mesG5tmS2AUPxna3z 0jY+7II=\n' Decrypted: "This world is round, not flat, don't believe them!"
I hope this helps the next person!!!! Thanks -D
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