Fix PKCS7Pad() error

[whoisnian]

#7

[whoisnian]

go run cookie.go | ruby cookie.rb to test.
JSON.stringify({cid:"1234567"}).length is 17, so it's ok.
JSON.stringify({cid:"123456"}).length is 16, and rails will throw error.

cookie.go

package main

import (
	"fmt"

	"github.com/mattetti/goRailsYourself/crypto"
)

type MySession struct {
	CID string `json:"cid"`
}

func main() {
	railsSecret := "this is a secret"
	encryptedCookieSalt := []byte("encrypted cookie")
	encryptedSignedCookieSalt := []byte("signed encrypted cookie")

	kg := crypto.KeyGenerator{Secret: railsSecret}
	secret := kg.CacheGenerate(encryptedCookieSalt, 32)
	signSecret := kg.CacheGenerate(encryptedSignedCookieSalt, 64)
	e := crypto.MessageEncryptor{Key: secret, SignKey: signSecret}

	session := MySession{CID: "1234567"}
	msg, err := e.EncryptAndSign(session)
	if err != nil {
		panic(err)
	}
	fmt.Print(msg)
}

cookie.rb

#!/usr/bin/env ruby
# frozen_string_literal: true

# https://blog.iany.me/zh/2017/09/rails-cookie-encryption/

require 'active_support'
require 'json'

SECRET_KEY_BASE   = 'this is a secret'
DEFAULT_SALT      = 'encrypted cookie'
DEFAULT_SIGN_SALT = 'signed encrypted cookie'

key_generator = ActiveSupport::KeyGenerator.new(SECRET_KEY_BASE, iterations: 1000)
encrypt_key = key_generator.generate_key(DEFAULT_SALT, 32)
sign_key = key_generator.generate_key(DEFAULT_SIGN_SALT, 64)

encryptor = ActiveSupport::MessageEncryptor.new(encrypt_key, sign_key, serializer: JSON)
inputs = gets
puts inputs

res = encryptor.decrypt_and_verify(CGI.unescape(inputs))
puts res.to_json.length
puts res.to_json