Crypto Crystal

Pure Crystal port of pyrogram/tgcrpto. Implements various Cryptograpgy algorithms that are especially usefull for Telegram's MTPtoto protocol.

Installation

Add the dependency to your shard.yml:

dependencies:
  crypto:
    github: watzon/crypto

Run shards install

API

module Crypto
  module AES
    def self.create_encryption_key(key : Bytes) : Slice(UInt32)
    def self.create_decryption_key(key : Bytes) : Slice(UInt32)
    def self.encrypt(data : Bytes, key : Indexable(UInt32)) : Bytes
    def self.decrypt(data : Bytes, key : Indexable(UInt32)) : Bytes
  end

  module CBC
    def self.encrypt(data : Bytes, key : Bytes, iv : Bytes) : Bytes
    def self.decrypt(data : Bytes, key : Bytes, iv : Bytes) : Bytes
  end

  module CTR
    def self.xcrypt(data : Bytes, key : Bytes, iv : Bytes, state : Bytes = [0_u8]) : Bytes
  end

  module IGE
    def self.encrypt(data : Bytes, key : Bytes, iv : Bytes) : Bytes
    def self.decrypt(data : Bytes, key : Bytes, iv : Bytes) : Bytes
  end

  module Padding
    def self.pkcs7(buffer : Bytes, block_size : Int)
  end
end

Usage

IGE Mode

Note: Data must be padded to match a multiple of the block size AES::BLOCK_SIZE.

require "crypto"

random = Random.new

# 10 MB of random data + 7 bytes to show padding
data = random.random_bytes(10 * 1024 * 1024 + 7)

key = random.random_bytes(32) # Random key
iv = random.random_bytes(32) # Random iv

# Pad the data using PKCS7
data = Crypto::Padding.pkcs7(data, Crypto::AES::BLOCK_SIZE)

encrypted = Crypto::IGE.encrypt(data, key, iv)
decrypted = Crypto::IGE.decrypt(encrypted, key, iv)

puts data == decrypted
# => true

CTR Mode

require "crypto"

random = Random.new

# 10 MB of random data + 7 bytes to show padding
data = random.random_bytes(10 * 1024 * 1024 + 7)

key = random.random_bytes(32) # Random key
iv = random.random_bytes(16) # Random iv

# Pad the data using PKCS7
data = Crypto::Padding.pkcs7(data, Crypto::AES::BLOCK_SIZE)

encrypted = Crypto::CTR.xcrypt(data, key, iv)
decrypted = Crypto::CTR.xcrypt(encrypted, key, iv)

puts data == decrypted

CBC Mode