shredder_encryptor

A small, dependency-free playground for encoding and encryption in Python. The project bundles a handful of classical ciphers, an opinionated encoding toolbox, a tiny framework for wiring ciphers together and a small on-disk key store. Everything relies on the standard library only.

Status

Early-stage example code. The shipped ciphers (Vigenère, XOR-stream, Feistel block ciphers, SHA-256 wrapper) are intended for learning and experimentation; do not use them to protect real secrets.

Installation

pip install shredder-encryptor

Layout

shredder_encryptor/
  codec/        # encoding helpers (text, hex, base64, padding, ...)
  framework/    # BaseCipher, Pipeline, testing utilities
  cipher/       # ready-to-use algorithms (Vigenère, XorStream, ...)
  persistence.py # tiny on-disk key store
tests/          # pytest suite (codec, framework, cipher, persistence)

codec — encoders in one place

from shredder_encryptor import codec

codec.encode(b"hello")                # standard base64
codec.encode_url(b"hello")            # URL-safe base64
codec.pkcs7_pad(b"hi", 8)             # PKCS#7 block padding
codec.token_urlsafe(32)               # secrets.token_urlsafe wrapper
codec.hexdigest(b"hello", "sha1")     # hashlib wrapper

framework — compose ciphers, test them

from shredder_encryptor.cipher import VigenereCipher, XorStreamCipher
from shredder_encryptor.framework import Pipeline, assert_round_trip

pipeline = Pipeline([VigenereCipher(b"alpha"), XorStreamCipher(b"beta")])
assert_round_trip(pipeline, b"pipeline payload")

cipher — concrete algorithms

from shredder_encryptor.cipher import (
    VigenereCipher, XorStreamCipher, FeistelEcbCipher, FeistelCbcCipher,
    Sha256Hash,
)

ct = FeistelCbcCipher(b"my-key").encrypt(b"hello world")
pt = FeistelCbcCipher(b"my-key").decrypt(ct)

persistence — small key store

from shredder_encryptor.persistence import save_key, load_key, list_keys

save_key("api-token", b"super-secret-bytes")
print(list_keys())               # ['api-token']
load_key("api-token")            # b'super-secret-bytes'

Keys live in ~/.shredder_encryptor/keys/ by default with 0o600 permissions on POSIX and ACL-stripped equivalents on Windows.

Conventions

• Public APIs are typed and re-exported through each package's __init__.py. Internal helpers start with an underscore.
• Cipher classes inherit from framework.BaseCipher; setting DECRYPTABLE = False marks a one-way cipher.
• codec mirrors the style of well-known libraries (e.g. hashlib, secrets, base64) but keeps a single import root.

Security notice

The ciphers in shredder_encryptor.cipher are pedagogical. FeistelEcbCipher / FeistelCbcCipher use a hand-rolled block cipher with a tiny key size. VigenereCipher and XorStreamCipher provide no authentication. For real-world cryptography, use a vetted library such as cryptography.

License

MIT. See LICENSE.