arcipher

A Go library and CLI tool for classical cryptography and cryptanalysis. Provides implementations of historical ciphers with file processing and concurrent operations.

Overview

Library: Core cipher implementations and cryptanalysis algorithms for use in Go projects.

CLI: arcipher command-line tool for encrypting, decrypting, and analyzing text and files with support for concurrent block processing.

Ciphers

Cipher Name	Cipher Type	Variant
Rail Fence	Permutation	—
Caesar	Substitution	—
Cardan	Hole Permutation	—
Vigenere	Polyalphabetic Substitution	Autokey (-a)
Affine	Polygraphic Substituion	Hill

Analyzers

Analyzer Name	Ciphers
Frequency Analysis	Caesar
Kasiski Test & Frequency Analysis	Vigenere

Padding

Padding Scheme
ISOIEC7816

Math Utilities

Matrix operations and modular arithmetic utilities for classical cipher implementations.

Installation

Prerequisites

• Go 1.25.5 or later

As a Library

go get github.com/ItakawaM/arcipher

As a CLI Tool

macOS / Linux:

go build -o arcipher ./cmd/arcipher

or

make build BINARY=arcipher

Windows:

go build -o arcipher.exe ./cmd/arcipher

or

make build

Library Usage

package main

import "github.com/ItakawaM/arcipher/ciphers"

func main() {
 // Create a new cipher
 cipher, err := ciphers.NewCaesarCipher(12)
 if err != nil {
  // Process error
 }

 // Create source and destination buffers
 src := []byte("HelloWorld")
 dst := make([]byte, len(src))

 // Perform action
 if err := cipher.EncryptBlock(dst, src); err != nil {
  // Process error
 }

 // Alternatively, you can alias buffers if the desired cipher allows it
 if cipher.IsInPlace() {
  if err := cipher.EncryptBlock(src, src); err != nil {
   // Process error
  }
 }
}

CLI Usage

Basic pattern:

arcipher <CIPHER> <ACTION> <ARGS> [FLAGS]

Getting help:

arcipher <COMMAND> --help

Verbose output:

arcipher <COMMAND> --verbose

Railfence

Message Encryption/Decryption with key 3

arcipher railfence encrypt 3 "helloworld" 
arcipher railfence decrypt 3 "loelwrdhol"

File Encryption/Decryption with key 10 using 4 threads and blocks of size 1024KB and verbose output

arcipher railfence encrypt 10 ./example/SunPoem ./example/SunPoem.enc --block 1024 --threads 4 -v
arcipher railfence decrypt 10 ./example/SunPoem.enc ./example/SunPoem --block 1024 --threads 4 -v

Caesar

Message Encryption/Decryption with key 15

arcipher caesar encrypt 15 "helloworld"
arcipher caesar decrypt 15 "wtaadldgas"

Message Bruteforce and Frequency Analysis

arcipher caesar bruteforce "wtaadldgas"
arcipher caesar analyze "wtaadldgas"

File Encryption/Decryption with key 5 using 2 threads and blocks of size 256KB

arcipher caesar encrypt 5 ./example/SunPoem ./example/SunPoem.enc --block 256 --threads 2
arcipher caesar decrypt 5 ./example/SunPoem.enc ./example/SunPoem --block 256 --threads 2

File Bruteforce using 6 threads and blocks of size 2048KB and Frequency Analysis

arcipher caesar bruteforce ./example/SunPoem /example/SunPoem_Directory -t 6 -b 2048
arcipher caesar analyze ./example/SunPoem

Cardan

Message Encryption/Decryption via interactive browser UI and key export

arcipher cardan encrypt "helloworld" --export key.json
arcipher cardan decrypt "h lowd e ol  lr "

Message Encryption/Decryption with exported/generated key

arcipher cardan encrypt ./key.json "helloworld"
arcipher cardan decrypt ./key.json "h lowd e ol  lr "

Generate a key for a 5x5 grid

arcipher cardan generate-key 5 key.json

File Encryption/Decryption with key and 4 threads

arcipher cardan encrypt key.json ./example/SunPoem ./example/SunPoem.enc --threads 4 -v
arcipher cardan decrypt key.json ./example/SunPoem.enc ./example/SunPoem --threads 4 -v

Vigenere

Message Encryption/Decryption with key "Secret"

arcipher vigenere encrypt "Secret" "helloworld"
arcipher vigenere decrypt "Secret" "zincspgvnu"

Message Dictionary Bruteforce and Kasiski-Frequency Analysis

arcipher vigenere bruteforce ./example/dict.txt "zincspgvnu"
arcipher vigenere analyze "zincspgvnu"

File Encryption/Decryption with key "Keyword" using 4 threads and blocks of size 512KB

arcipher vigenere encrypt "Keyword" ./example/SunPoem ./example/SunPoem.enc --block 512 --threads 4
arcipher vigenere decrypt "Keyword" ./example/SunPoem.enc ./example/SunPoem --block 512 --threads 4

File Dictionary Bruteforce using 4 threads and Kasiski-Frequency Analysis

arcipher vigenere bruteforce ./example/dict.txt ./example/SunPoem /example/SunPoem_Directory --threads 4
arcipher vigenere analyze ./example/SunPoem.enc

Message Encryption/Decryption with Autokey variant using -a flag

arcipher vigenere encrypt "Secret" "helloworld" -a
arcipher vigenere decrypt "Secret" "zincspvvwo" -a

File Encryption/Decryption with Autokey variant using 4 threads

arcipher vigenere encrypt "Keyword" ./example/SunPoem ./example/SunPoem.enc --block 512 --threads 4 -a
arcipher vigenere decrypt "Keyword" ./example/SunPoem.enc ./example/SunPoem --block 512 --threads 4 -a

Affine

Generate an Affine cipher key

arcipher affine generate-key 3 key.json
arcipher affine generate-key 25 key.json --template

Message Encryption/Decryption with key

arcipher affine encrypt ./key.json "HELLOWORLD"
arcipher affine decrypt ./key.json "ZICVTWQNGRZGVTWAVZHCQYGLMGJ"

File Encryption/Decryption with key and 4 threads

arcipher affine encrypt key.json ./example/input ./example/input.enc --threads 4 -v
arcipher affine decrypt key.json ./example/input.enc ./example/output --threads 4 -v

Options

• -v, --verbose — Show performance metrics
• -b, --block — Block size in KB for file processing (default: 64)
• -t, --threads — Worker threads for file processing (default: CPU cores / 2)

Testing

go test ./tests/...

or

make test

License

MIT License — see LICENSE