Encrypt text in file with ruby and cipher - ruby-on-rails

Question

I need to make an encryptor and decryptor which reads a file with text and encrypts it and then generates a txt file with the encryption.
Then you must decrypt that same txt file
So far I managed to encrypt the text and put it in the file but I still can not decrypt the text that is inside this.
The encrypt work without the files
**The problem starts here**
#Decrypt
data = ''
File.open('text2.txt','r') do |archivo|
while line = archivo.gets
data += line
end
end
encrypted = data
cipher = OpenSSL::Cipher::Cipher.new("aes-256-cbc")
cipher.decrypt
cipher.key = key
cipher.iv = iv
# and decrypt it
decrypted = cipher.update(encrypted)
decrypted << cipher.final
puts "decrypted: #{decrypted}\n"
The error is : encrypt.rb:48:in final': wrong final block length (OpenSSL::Cipher::CipherError)
from encrypt.rb:48:in'

Answer 1

The issue is in the block where you write out the encryption to the file text2.txt. You're using archivo.puts, but you want to use archivo.write. puts will append a newline character at the end of each line, so you're writing encrypted + "\n" to the file. When you try to decrypt it, that extra newline character messes it up. If you use write, it just writes exactly what you give it without the extra character.
What you want to do instead:
File.open('text2.txt', 'w') do |archivo|
archivo.write encrypted
end
Or even better yet:
File.write('text2.txt', encrypted)