微信退款成功回调通知数据解密

decrypt_wechat_refund_callback_data.rb

def refund_notify
  encrypt_result = Hash.from_xml(request.body.read)["xml"]
  decrypt_result = Hash.from_xml(decrypt_data(encrypt_result['req_info']))['root']
  # other logic code (decrypt_result['out_refund_no'])

  render :xml => {return_code: "SUCCESS"}.to_xml(root: 'xml', dasherize: false)
end

private

# https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=9_16
def decrypt_data(encrypted_base64)
  encrypted = Base64.decode64(encrypted_base64)
  decipher = OpenSSL::Cipher::AES256.new(:ECB)
  decipher.decrypt
  decipher.key = Digest::MD5.hexdigest(Rails.application.secrets.wechat[:mch_key])
  data = decipher.update(encrypted) + decipher.final
  data
end