Checks aead gem compatibility with OpenSSL core in ruby >= 2

gcm_core_aead_gem_compat.rb

# Requires Ruby >= 2

require "openssl"
require "aead"

key = Digest::SHA256.digest("key") # digest_length 32
algorithm = "aes-256-gcm"
data = "plaintext data"
auth_data = "authentication data"

puts "Encryption using OpenSSL"
cipher = OpenSSL::Cipher.new(algorithm) # key len 32
cipher.encrypt
cipher.key = key
cipher.iv = iv = cipher.random_iv
cipher.auth_data = auth_data
enc_data = cipher.update(data) + cipher.final
tag = cipher.auth_tag
puts "  enc_data length: #{enc_data.length}"
puts "  iv length: #{iv.length}"
puts "  tag length: #{tag.length}"

puts "\nDecryption using AEAD"
mode = AEAD::Cipher.new(algorithm)
cipher = mode.new(key)
ciphertext = enc_data + tag
plaintext = cipher.decrypt(iv, auth_data, ciphertext)
puts "  plaintext: #{plaintext}"

puts "\nEncryption using AEAD"
mode = AEAD::Cipher.new(algorithm)
key = mode.generate_key
iv = mode.generate_nonce
cipher = mode.new(key)
ciphertext = cipher.encrypt(iv, auth_data, data)
tag = ciphertext[ -cipher.class.tag_len .. -1 ].to_s
enc_data = ciphertext[ 0 .. -cipher.class.tag_len - 1 ].to_s
puts "  enc_data length: #{enc_data.length}"
puts "  iv length: #{iv.length}"
puts "  tag length: #{tag.length}"

puts "\nDecryption using OpenSSL"
decipher = OpenSSL::Cipher.new(algorithm)
decipher.decrypt
decipher.key = key
decipher.iv = iv
decipher.auth_data = auth_data
decipher.auth_tag = tag
plaintext = decipher.update(enc_data) + decipher.final
puts "  plaintext: #{plaintext}"