使用python重新创建CryptoJS Hmac [英] Recreating a CryptoJS Hmac using python

问题描述

这种情况是，我有一个JS脚本为用户提供的输入创建HMAC，并且我想使用python为相同的输入计算相同的HMAC.为了使事情更清楚，请考虑以下JS和Python代码段.

JavaScript

 <脚本src ="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/crypto-js.min.js"</script>< script src ="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/hmac-sha256.min.js"</script>< script src ="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/enc-base64.min.js"</script>< script>var secretAccessKey ="bAvW5O18eSrxke4I7eFcrnrDJkN + wKQmx9aSHuMZQ0w =";var stringtoSign =测试";//生成HMAC SHA256签名var secretAccessKeyBase64 = CryptoJS.enc.Base64.parse(secretAccessKey);var hash = CryptoJS.HmacSHA256(stringtoSign，secretAccessKeyBase64);var signature = CryptoJS.enc.Base64.stringify(hash);</script> 

Python

  stringToSign =测试"secretAccessKey ="bAvW5O18eSrxke4I7eFcrnrDJkN + wKQmx9aSHuMZQ0w ="secretAccessKeyBase64 = base64.b64decode(secretAccessKey).hex()keyBytes =字节(secretAccessKeyBase64，'utf-8')stringToSignBytes =字节(stringToSign，'utf-8')signatureHash = hmac.new(keyBytes，stringToSignBytes，digestmod = hashlib.sha256).digest()签名= base64.b64encode(signatureHash)打印(签名) 

Javascript代码给我 b + 1wRzDODA85vyDZkXByPIKO5qmnjCRNF5gZFi33/Ic = ，而python给我值 b'SsZ4bcYe3op1nGU6bySzlSc9kgg9Kgp37qzF15s2zN>

为什么我的python代码为(似乎)提供给JS脚本的相同输入生成一个不同的HMAC?无论如何，要使用python获取JS代码输出的HMAC值?

解决方案

您在Javascript中使用Base64编码值作为机密，而在Python中，您使用纯文本机密.

 < script>var secretAccessKeyBase64 =秘密";var hash = CryptoJS.HmacSHA256("Message"，secretAccessKeyBase64);var hashInBase64 = CryptoJS.enc.Base64.stringify(hash);document.write(hashInBase64);</script> 

这将输出与Python代码相同的值:

  qnR8UCqJggD55PohusaBNviGoOJ67HC6Btry4qXLVZc = 

base64返回一个字节对象，无需将其转换为 hex():

  stringToSign =测试"secretAccessKey ="bAvW5O18eSrxke4I7eFcrnrDJkN + wKQmx9aSHuMZQ0w ="secretAccessKeyBase64 = base64.b64decode(secretAccessKey)keyBytes = secretAccessKeyBase64stringToSignBytes =字节(stringToSign，'utf-8')signatureHash = hmac.new(keyBytes，stringToSignBytes，digestmod = hashlib.sha256).digest()签名= base64.b64encode(signatureHash)打印(签名) 

正确打印:

  b'b + 1wRzDODA85vyDZkXByPIKO5qmnjCRNF5gZFi33/Ic =' 

The scenario is that I have a JS script that creates a HMAC for a user provided input and I want to compute the same HMAC for the same input using python. To make things clearer, consider the following JS and Python code snippets.

Javascript

<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/crypto-js.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/hmac-sha256.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/enc-base64.min.js"></script>

<script>
    var secretAccessKey = "bAvW5O18eSrxke4I7eFcrnrDJkN+wKQmx9aSHuMZQ0w=";
    var stringtoSign = "Test";

    // Generate HMAC SHA256 signature
    var secretAccessKeyBase64 = CryptoJS.enc.Base64.parse(secretAccessKey);
    var hash = CryptoJS.HmacSHA256(stringtoSign, secretAccessKeyBase64);
    var signature = CryptoJS.enc.Base64.stringify(hash);
</script>

Python

stringToSign = "Test"
secretAccessKey = "bAvW5O18eSrxke4I7eFcrnrDJkN+wKQmx9aSHuMZQ0w="

secretAccessKeyBase64 = base64.b64decode(secretAccessKey).hex()
keyBytes = bytes(secretAccessKeyBase64, 'utf-8')
stringToSignBytes = bytes(stringToSign, 'utf-8')
signatureHash = hmac.new(keyBytes, stringToSignBytes, digestmod=hashlib.sha256).digest()
signature = base64.b64encode(signatureHash)
print(signature)

The Javascript code gives me b+1wRzDODA85vyDZkXByPIKO5qmnjCRNF5gZFi33/Ic=, while python gives me the value b'SsZ4bcYe3op1nGU6bySzlSc9kgg9Kgp37qzF15s2zNc='

Why is my python code generating a different HMAC for (seemingly) identical inputs that was provided to the JS script? Is there anyway to obtain the HMAC value outputted by the JS code using python?

解决方案

You are using a Base64 encoded value as secret in Javascript, whereas in Python you use the plain text secret.

<script>
    var secretAccessKeyBase64 = "secret";
    var hash = CryptoJS.HmacSHA256("Message", secretAccessKeyBase64);
    var hashInBase64 = CryptoJS.enc.Base64.stringify(hash);
    document.write(hashInBase64);
</script>

This prints out the same value as the Python code:

qnR8UCqJggD55PohusaBNviGoOJ67HC6Btry4qXLVZc=

Edit:

base64 returns a byte-object there is no need to convert it to hex():

stringToSign = "Test"
secretAccessKey = "bAvW5O18eSrxke4I7eFcrnrDJkN+wKQmx9aSHuMZQ0w="

secretAccessKeyBase64 = base64.b64decode(secretAccessKey)
keyBytes = secretAccessKeyBase64
stringToSignBytes = bytes(stringToSign, 'utf-8')

signatureHash = hmac.new(keyBytes, stringToSignBytes, digestmod=hashlib.sha256).digest()
signature = base64.b64encode(signatureHash)
print(signature)

Prints correctly:

b'b+1wRzDODA85vyDZkXByPIKO5qmnjCRNF5gZFi33/Ic='

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