encrypt-decrypt.rb

require 'openssl'
require 'base64'

# AES256 encryption
def aes_encrypt(text, key)
	cipher = get_cipher.tap { _1.encrypt; _1.key = key }
	iv = cipher.random_iv  # 16 bytes
	cipher_text = cipher.update(text) + cipher.final
	# *ensure there is no newline char in the encoded text
	Base64.strict_encode64(iv + cipher_text)
end

def aes_decrypt(encoded_text, key)
	decoded_text = Base64.decode64(encoded_text)
	iv, cipher_text = decoded_text.then { [_1[0..15], _1[16..]] }
	cipher = get_cipher.tap { _1.decrypt; _1.key = key; _1.iv = iv }
	cipher.update(cipher_text) + cipher.final
end

def get_cipher
	OpenSSL::Cipher::AES256.new(:CBC)
end

# predefined text and key for demo
text = "This is a secret message."
key = "12345678901234567890123456789012" # 32-byte key

puts "Original text:  #{text}"

encrypted_text = aes_encrypt(text, key)
puts "Encrypted text: #{encrypted_text}"

decrypted_text = aes_decrypt(encrypted_text, key)
puts "Decrypted text: #{decrypted_text}"