微信公众平台企业号验证URL (处理 echostr)

verify_url_echostr.rb

require 'openssl'
require 'base64'

# 参考 http://qydev.weixin.qq.com/wiki/index.php?title=加解密方案的详细说明

AES_KEY = 'aaaa'
encrypted_enchostr = 'bbbb'

def parse_msg(text)
  random = text[0..16]
  msg_len = text[16, 4].reverse.unpack('V')[0]
  content = text[20, msg_len]
  corp_id = text[(20+msg_len-1)..-1]

  return content, corp_id
end

def decrypt(text)
  decipher = OpenSSL::Cipher.new('AES-256-CBC')
  decipher.decrypt

  decipher.padding = 0
  key_data = Base64.decode64(AES_KEY)
  decipher.key = key_data
  decipher.iv = key_data[0..16]

  plain = decipher.update(Base64.decode64(text)) + decipher.final
  truncate_padding(plain)
end

def truncate_padding(plain)
  pad = plain.bytes[-1]
  # no padding
  pad = 0 if pad < 1 || pad > 32
  plain[0...(plain.length - pad)]
end

# echostr 就是解密后 echostr 的明文内容
echostr, corp_id = parse_msg(decrypt(encrypted_echostr))
puts echostr