跨平台AES 256 GCM Javascript和Elixir

Posted 2021-04-13

我一直在尝试使用带有GCM的AES 256在javascript中加密并在Elixir中解密。我从这里和那里借了一些例子，想出了以下内容。

Javascript中的加密

const _crypto = require('crypto');

function encrypt(message, secret) {
  // random initialization vector
  const iv = _crypto.randomBytes(16);

  // extract the auth tag
  const cipher = _crypto.createCipheriv('aes-256-gcm', secret, iv);

  // encrypt the given text
  const encrypted = Buffer.concat([cipher.update(message, 'utf8'), cipher.final()]);

  // extract the auth tag
  const tag = cipher.getAuthTag();

  const encrypted_message = Buffer.concat([iv, tag, encrypted]).toString('base64');
  return encrypted_message;
}

const secret = _crypto.randomBytes(32);
encrypt("secret message", secret);

Elixir中的解密

def decrypt(encrypted_message, secret) do
  secret_key = :base64.decode(secret)
  ciphertext = :base64.decode(encrypted_message)

  <<iv::binary-16, tag::binary-16, ciphertext::binary>> = ciphertext
  :crypto.block_decrypt(:aes_gcm, secret_key, iv, {"AES256GCM", ciphertext, tag})
end

# secret would be the secret from javascript encoded in base64
decrypt(encrypted_message, secret)

而我在Elixir方面的结果一直是:error我感觉它与编码和解码有关，但我似乎无法找出哪里出了什么问题。

如果有人能指出我正确的方向将不胜感激。

谢谢！

更新的工作版本

对于打算使用相同语言的人：

Javascript加密

const _crypto = require('crypto');

function encrypt(message, secret) {
  // random initialization vector
  const iv = _crypto.randomBytes(16);

  // extract the auth tag
  const cipher = _crypto.createCipheriv('aes-256-gcm', secret, iv);

  // add the following line if you want to include "AES256GCM" on the elixir side
  // cipher.setAAD(Buffer.from("AES256GCM", 'utf8'));

  // encrypt the given text
  const encrypted = Buffer.concat([cipher.update(message, 'utf8'), cipher.final()]);

  // extract the auth tag
  const tag = cipher.getAuthTag();

  const encrypted_message = Buffer.concat([iv, tag, encrypted]).toString('base64');
  return encrypted_message;
}

const secret = _crypto.randomBytes(32);
encrypt("secret message", secret);

Elixir Decryption

def decrypt(encrypted_message, secret) do
  secret_key = :base64.decode(secret)
  ciphertext = :base64.decode(encrypted_message)

  <<iv::binary-16, tag::binary-16, ciphertext::binary>> = ciphertext

  // make sure _AAD is an empty string "" if you didn't set it during encryption
  :crypto.block_decrypt(:aes_gcm, secret_key, iv, {_AAD, ciphertext, tag})

  // otherwise, you would need to set _AAD to whatever you set during encryption, using "AES256GCM" as example
  // Note: AAD (Associated Authenticated Data) can be whatever string you want to my knowledge, just to make sure you have the same in both encryption and decryption process
  // :crypto.block_decrypt(:aes_gcm, secret_key, iv, {"AES256GCM", ciphertext, tag})
end

# secret would be the secret from javascript encoded in base64
decrypt(encrypted_message, secret)

答案

这很简单：你的"AES256GCM"不应该存在（或者null，我不熟悉Erlang）。它表示附加的经过身份验证的数据，并包含在身份验证标记的计算中，显然使其与加密代码生成的身份验证标记不同。

:aes_gcm已经指定了模式，键大小当然是由secret_key的大小决定的，所以无论如何这个字符串都是非常不必要的。