Python 3.8.3 : PyCryptodome python package - part 001.

In the last tutorial, I wrote on Sunday, June 16, 2019, you can see a simple example of this python package with KDF with PBKDF2 function.

I guess it should be interesting for visitors to this blog to read more about this package because it is very useful and interesting.

Today I come up with another tutorial covering how to use A.E.S. standard encryption and decrypting text in a binary file.

The A.E.S. is a standard?

The Federal Information Processing Standards Publications (FIPS PUBS) announcing the A.E.S. on November 26, 2001, on the Federal Information Processing Standards Publication 197.

A.E.S. known as Advanced Encryption Standard is a symmetric block cipher standardized by NIST.

The N.I.S.T is an abbreviation National Institute of Standards and Technology.

This python package named PyCryptodome is a self-contained Python package of low-level cryptographic primitives, see the readthedocs.io webpage.

First, you need to see if this python package is not on conflict with another one named PyCrypto.

Then use pip3 tool to install.

pip3 uninstall PyCrypto
WARNING: Skipping PyCrypto as it is not installed.
...
pip3 install pycryptodome
Collecting pycryptodome
...
Installing collected packages: pycryptodome
Successfully installed pycryptodome-3.9.8

Here is the source code commented for a better understanding of the encryption and decryption steps.

from Crypto.Cipher import AES
from Crypto.Random import get_random_bytes

# the data input needs to be encoded, else you will receive this error
# python TypeError: Object type  cannot be passed to C code

data = "Hello World! by catafest!".encode("utf8")
# first step - prepare for encrypt
key = get_random_bytes(16)
print("print key is: ", key)
cipher = AES.new(key, AES.MODE_EAX)
print("print cipher is: ", cipher)
ciphertext, tag = cipher.encrypt_and_digest(data)
print("print ciphertext is: ", ciphertext)

# open the binary file 
file_out = open("AES_encrypted.bin", "wb")
# write to binary file 
[ file_out.write(x) for x in (cipher.nonce, tag, ciphertext) ]

# the file is close 
file_out.close()

# next step - prepare for decrypt
new_cipher = AES.new(key, AES.MODE_EAX, cipher.nonce)

# open again the binary file 
file_in = open("AES_encrypted.bin", "rb")
# read all data from file
nonce, tag, ciphertext = [file_in.read(x) for x in (16, 16, -1) ]
# the file is close 
file_out.close()

# show data from file
print("print nonce is: ", nonce)
print("print tag is: ", tag)
print("print ciphertext is: ", ciphertext)

# create a new cipher
cipher = AES.new(key, AES.MODE_EAX, nonce)

# use this to decrypt
data = cipher.decrypt_and_verify(ciphertext, tag)
# show the result 
print(data)

The result of running the python script is this:

python.exe .\pycryptodome_AES_001.py
print key is:  b'\xbdEX\xf8\x1d!\xc5\xceI\x87\x81\xf1\xd5\xba\x8c\r'
print cipher is:  <Crypto.Cipher._mode_eax.EaxMode object at 0x000001D5F32DE100>
print cipher is:  <Crypto.Cipher._mode_eax.EaxMode object at 0x000001E062AFE100>
print ciphertext is:  b'ON\x1d\xb9\xb7\xa8\xf5\xd6\x0c\x91\xc5`B\xf4\x95u\xe1D\xb5\x88&I\x15\xc5\xc5'
print nonce is:  b'3\xa6R8\xbb\n \x9cimp$\xe4\xee\xf5-'
print tag is:  b'\xb8)\xe4\xe7\x08uE~\x84s]\xedX\xf5\xf9\xea'
print ciphertext is:  b'ON\x1d\xb9\xb7\xa8\xf5\xd6\x0c\x91\xc5`B\xf4\x95u\xe1D\xb5\x88&I\x15\xc5\xc5'
b'Hello World! by catafest!'

You can read about this process on this website.

Python 2.7.10 : IronPython and C# with Dynamic Language Runtime.

This is a simple tutorial about python and C# using the Dynamic Language Runtime with IronPython.

I use Visual Studio 2019 and .NET Framework 4.7.2 with my Console C# project named DynamicLanguageRuntime_001.

Let's install the package with Visual Studio by open the console using the main menu: Tools - NuGet Package Manager - Package Manager Console command.

PM> Install-Package DynamicLanguageRuntime
Package 'DynamicLanguageRuntime.1.2.3' already exists in project 'DynamicLanguageRuntime_001'
Time Elapsed: 00:00:01.2208674

Use Solution Explorer use right-click on References item from your project and use Add Reference ...

Into the new window dialog named Reference Manager on the Assemblies - Framework uses the edit box to search IronPython.

Then use the checkbox to select these two options: IronPython and IronPython.Modules.

See the screenshot from Visual Studio I.D.E.:

This is the source code I used:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using IronPython.Hosting;
using IronPython.Runtime;
using IronPython;
using Microsoft.Scripting.Hosting;
using Microsoft.Scripting;

namespace DynamicLanguageRuntime_001
{
    class Program
    {
        static void Main(string[] args)
        {
            // create python engine 
            ScriptEngine engine = Python.CreateEngine();
            // get and add paths to enfine
            var python_search_paths = engine.GetSearchPaths();
            python_search_paths.Add(@"C:\Program Files\IronPython 2.7\Lib");
            engine.SetSearchPaths(python_search_paths);
            // create a scope 
            ScriptScope scope = engine.CreateScope();
            // using CreateScriptSourceFromString
            engine.CreateScriptSourceFromString("print '... simple example with ironpython and C#'").Execute();
            // using Execute
            engine.Execute("print '                             by catafest!'", scope);
            // using ExecuteFile
            engine.ExecuteFile(@"D:\Projects\Python\testing\test_webpage_001.py", scope);
            dynamic testFunction = scope.GetVariable("GetFriends");
            var result = testFunction();
        }
    }
}