Rails 5 cipher.key "key must be 32 bytes" error - ruby-on-rails

Question

Brand new Rails application.
Rails version 5.0.0.1, Ruby version 2.4.0preview2.
Create application "demo", run a simple scaffold generate Product, and get an error when trying to view the scaffold's overview page (base index file still loads the Welcome to Rails screen fine):
ArgumentError in ProductsController#index
key must be 32 bytes:
cipher = new_cipher
cipher.encrypt
cipher.key = #secret
# Rely on OpenSSL for the initialization vector
iv = cipher.random_iv
The problem line is apparently cipher.key = #secret.
I've seen various mentions on the github repo for Rails mentioning this issue, but all implied it was now resolved in Rails 5.0.0.1

Answer 1

Ok, there was a slight misunderstanding on my part, looks like the fix is coming in 5.0.1 not 5.0.0.1
https://github.com/rails/rails/issues/26694

Answer 2

Please use Digest::MD5 to achive 32 bytes
require 'openssl'
require 'digest'
require 'base64'
data = "encrypt me"
secret_key = "asd3dssdf34HDas"
c = OpenSSL::Cipher.new("aes-256-cbc")
c.encrypt
c.key = Digest::MD5.hexdigest(secret_key) # this will convert key length into 32
encrypted_data = c.update(data.to_s) + c.final
encrypted_data = Base64.urlsafe_encode64(encrypted_data, padding: false) #padding: false will remove '/', '+' from encrypted data
encrypted_data.gsub! "\n",""
Or Simply use secret key of length 32 bytes
data = "encrypt me"
secret_key = "Aswertyuioasdfghjkqwertyuiqwerty"
c = OpenSSL::Cipher.new("aes-256-cbc")
c.encrypt
c.key = secret_key
encrypted_data = c.update(data.to_s) + c.final

Answer 3

Finally found problem! It was from a bugfix... https://bugs.ruby-lang.org/issues/12561
If you are using cipher e.g. 'aes-256-cfb', the key_len is 32, found by:
require 'openssl'
cipher = OpenSSL::Cipher.new('aes-256-cfb')
cipher.key_len # => 32
We had mistakenly thought we needed to send a 256 character nonce, but actually you are supposed to send a 32 character nonce - or
use cipher.random_key (which internally uses the key_len). It never used to be a problem because openssl truncated the nonce... but now you need to send the right lengthed nonce.
We got this error upgrading ruby from 2.3.4 to 2.4.2.

Answer 4

This issue turns out to be connected to the key you are using. Without changing your key you can use the code below to transform your key to 32 bytes:
attr_encrypted :attribute, key: ENV['MY_KEY'].bytes[0..31].pack( "c" * 32 )

Answer 5

try this:
rake db:create
rake db:migrate
then, the most important thing:
bundle update
This works for me.

Answer 6

Use random_key so it always fit.
key = cipher.random_key
cipher.key = key
reference http://ruby-doc.org/stdlib-2.0.0/libdoc/openssl/rdoc/OpenSSL/Cipher.html

Answer 7

Solution:
Edit your Gemfile
Add the following line: gem 'rails', '~> 5.0.0', '>= 5.0.0.1'
bundle install
Optional: I am using ruby2-4.1 . (rvm install ruby-2.4.1)
Rational: The rails version prior to 5.0.0 seems to have a bug that causes this issue. The bug has been resolved in the latest version of Rails. If you hare following the Rails Installation Guide (http://railsapps.github.io/installrubyonrails-mac.html) you will probably encounter this problem as of this posting date.
This fix does work, and is verified by

Answer 8

I was having this problem too and fixed it by running
bundle update
Make sure that you have the latest version of rails installed.

Answer 9

Had the same error:
Running bundle update should do the trick