https://github.com/tniessen/cryptpad

Text editor for Windows supporting strong encryption
https://github.com/tniessen/cryptpad

aes-256 cryptpad decryption encryption notepad windows

Last synced: about 2 months ago
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Text editor for Windows supporting strong encryption

• Host: GitHub
• URL: https://github.com/tniessen/cryptpad
• Owner: tniessen
• License: mit
• Created: 2016-10-14T19:19:54.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2017-11-07T17:52:10.000Z (about 7 years ago)
• Last Synced: 2024-10-19T09:32:42.946Z (3 months ago)
• Topics: aes-256, cryptpad, decryption, encryption, notepad, windows
• Language: C#
• Homepage:
• Size: 50.8 KB
• Stars: 3
• Watchers: 2
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
[![Build status](https://ci.appveyor.com/api/projects/status/rdkgt36mc8ksjp7d?svg=true)](https://ci.appveyor.com/project/tniessen/cryptpad)

## Building and requirements

To build the program, simply open the Visual Studio 2015 solution and click Build. The resulting

binary `cryptpad.exe` requires the .NET Framework 4.

## Encryption

cryptpad uses AES encryption, supporting key lengths of up to 256 bits, and can generate keys using

either SHA-256 (default), SHA-512, RIPEMD-160 (128 bit keys only) or MD5 (128 bit keys only). Only

two block cipher modes of operation are supported, CBC (recommended) and ECB.

## File format

Encrypted text files begin with a 128 bit IV, followed by any number of encrypted blocks. Therefore,

the file size is always a multiple of the block size, which is 128 bits (16 bytes).

### Manual encryption and decryption using OpenSSL

You can, in fact, manually encrypt and decrypt text files exactly as cryptpad does, using OpenSSL.

The following example uses bash and assumes AES/CBC/PKCS7 with a 256 bit key generated using

SHA-256. However, only minimal changes are required to adapt the commands to other configurations.

First, you need to create the key:

```bash

key=`echo -n "$password" | sha256sum | head -c 64`

```

To encrypt content, generate a random initialization vector and its hexadecimal representation,

and use it in combination with the computed key in order to produce the output file:

```bash

dd if=/dev/random bs=16 count=1 status=none > file.stxt

iv=`xxd -c 32 -p file.stxt`

echo 'Hello world!' | openssl enc -aes-256-cbc -e -iv $iv -K $key >> file.stxt

```

You can now open `file.stxt` in cryptpad.

To decrypt the file, we need to read the IV before reading the actual contents:

```bash

iv=`dd if=file.stxt bs=16 count=1 status=none | xxd -c 32 -p`

dd if=file.stxt bs=16 skip=1 status=none | openssl enc -aes-256-cbc -d -iv $iv -K $key

```