AES128 / AES256 CBC with PKCS7Padding in Ruby

gistfile1.rb

require "openssl"
require "digest"

def aes128_cbc_encrypt(key, data, iv)
  key = Digest::MD5.digest(key) if(key.kind_of?(String) && 16 != key.bytesize)
  iv = Digest::MD5.digest(iv) if(iv.kind_of?(String) && 16 != iv.bytesize)
  aes = OpenSSL::Cipher.new('AES-128-CBC')
  aes.encrypt
  aes.key = key
  aes.iv = iv
  aes.update(data) + aes.final
end

def aes256_cbc_encrypt(key, data, iv)
  key = Digest::SHA256.digest(key) if(key.kind_of?(String) && 32 != key.bytesize)
  iv = Digest::MD5.digest(iv) if(iv.kind_of?(String) && 16 != iv.bytesize)
  aes = OpenSSL::Cipher.new('AES-256-CBC')
  aes.encrypt
  aes.key = key
  aes.iv = iv
  aes.update(data) + aes.final
end

def aes128_cbc_decrypt(key, data, iv)
  key = Digest::MD5.digest(key) if(key.kind_of?(String) && 16 != key.bytesize)
  iv = Digest::MD5.digest(iv) if(iv.kind_of?(String) && 16 != iv.bytesize)
  aes = OpenSSL::Cipher.new('AES-128-CBC')
  aes.decrypt
  aes.key = key
  aes.iv = iv
  aes.update(data) + aes.final
end

def aes256_cbc_decrypt(key, data, iv)
  key = Digest::SHA256.digest(key) if(key.kind_of?(String) && 32 != key.bytesize)
  iv = Digest::MD5.digest(iv) if(iv.kind_of?(String) && 16 != iv.bytesize)
  aes = OpenSSL::Cipher.new('AES-256-CBC')
  aes.decrypt
  aes.key = key
  aes.iv = iv
  aes.update(data) + aes.final
end

How to go for PKCS5 encrypting in Ruby? I can't find any information on this.