Gibberish library provides a nice CBC algo...

// In Jascascript
GibberishAES.enc("Made with Gibberish\n", "password");
// Outputs: "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o"

# On the mand line
echo "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o" | 
  openssl enc -d -aes-256-cbc -a -k password

How can I do this decryption in ruby? The straightforward way doesn't work...

require 'openssl'

def aes(m,k,t)
  (aes = OpenSSL::Cipher::Cipher.new('aes-256-cbc').send(m)).key = k
  aes.update(t) << aes.final
end

def encrypt(key, text)
  aes(:encrypt, key, text)
end

def decrypt(key, text)
  aes(:decrypt, key, text)
end

def p k
  Digest::SHA256.digest(k) ## what goes here???
end

require 'base64'
def t x
  ## also tried.. simply returning x...
  Base64.decode64(x)      
end


text = "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o"
pass = "password"

decrypt(p(pass), t(text))

Gibberish library provides a nice CBC algo...

// In Jascascript
GibberishAES.enc("Made with Gibberish\n", "password");
// Outputs: "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o"

# On the mand line
echo "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o" | 
  openssl enc -d -aes-256-cbc -a -k password

How can I do this decryption in ruby? The straightforward way doesn't work...

require 'openssl'

def aes(m,k,t)
  (aes = OpenSSL::Cipher::Cipher.new('aes-256-cbc').send(m)).key = k
  aes.update(t) << aes.final
end

def encrypt(key, text)
  aes(:encrypt, key, text)
end

def decrypt(key, text)
  aes(:decrypt, key, text)
end

def p k
  Digest::SHA256.digest(k) ## what goes here???
end

require 'base64'
def t x
  ## also tried.. simply returning x...
  Base64.decode64(x)      
end


text = "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o"
pass = "password"

decrypt(p(pass), t(text))

• javascript
• ruby
• openssl
• aes
• encryption

• the iv is not getting set... whats its default value? I have solved this in the past. stumbling at this again... aaargh... – Ryan Oberoi Commented Dec 21, 2009 at 6:02

2 Answers 2

Digging into Gibberish code... provides the clues to the answers. and why the traditional mechanism does not work.

dec = function(string, pass) {
    // string, password in plaintext
    var cryptArr = Base64.decode(string),
    salt = cryptArr.slice(8, 16),
    pbe = openSSLKey(s2a(pass), salt),
    key = pbe.key,
    iv = pbe.iv;
    cryptArr = cryptArr.slice(16, cryptArr.length);
    // Take off the Salted__ffeeddcc
    string = rawDecrypt(cryptArr, key, iv);
    return string;
},

Converting to ruby is now fairly trivial.. noting it down for my personal future reference.

require 'base64'
require 'openssl'

def decode(k,t)
  cryptArr = Base64.decode64(t)
  salt     = cryptArr[8..15]
  data     = cryptArr[16..-1] 

  aes = OpenSSL::Cipher::Cipher.new('AES-256-CBC').decrypt
  aes.pkcs5_keyivgen(k, salt, 1)
  s = aes.update(data) + aes.final
end

orig = "Made with Gibberish\n"
cipr = "U2FsdGVkX1+21O5RB08bavFTq7Yq/gChmXrO3f00tvJaT55A5pPvqw0zFVnHSW1o"
pass = "password"

puts decode(pass, cipr)

I wrote the original Gibberish JS library, and I finally got around to rectifying the situation in Ruby. The above code from Ryan Oberoi is absolutely correct, but I've gone ahead and created a gem to do the same thing. Check it out at https://github./mdp/gibberish