HKDF是否在Java Cryptography Architecture中实现？

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问题描述

在我写的应用程序中，我需要使用HKDF从一个密码中获取两个不同的密钥。在Java中搜索如何使用它的示例我发现了这两个：

In the application I'm writing I need to do HKDF to derive two different keys from one password. Searching for examples on how to it in Java I found these two:

https://github.com/WhisperSystems/libsignal-protocol-java/blob/master/java/src/main/java/org/whispersystems/libsignal/kdf/HKDF.java
https://www.javatips.net/api/keywhiz-master/hkdf/src/main/java/keywhiz/hkdf/Hkdf.java

在这两种情况下，HKDF都已实施在JCA提供的HMAC之上。我还没有详细阅读这些实现，但我想知道，这是不是在JCA或其自身的任何地方实现的？我是否必须实施自己的HKDF？

In both cases HKDF is implemented on top of the HMAC provided by JCA. I haven't read those implementations in detail yet but I was wondering, is this not implemented anywhere in JCA or itself? Do I have to implement my own HKDF?

最让我担心的部分是在应用info参数时出错。它看起来非常重要和关键。

The part that worries me the most, is making a mistake in applying the info argument. It looks non-trivial and critical.

HKDF Java实现

不，

mozilla-services/sync-crypto
WhisperSystems/libsignal-protocol-java
square/keywhiz

当然，还有使用自己的Hmac / Mac实现和API。然而，BC是一种巨大的依赖性，并且对于例如BC可能是不实用的。嵌入式或移动用例。为此，我实现了一个独立，轻量级java lib（传递所有RFC 5869测试向量），它适用于任何实例：

Also there is, of course, Bouncy Castle which use their own Hmac/Mac implementations and APIs. BC is however a massive dependency, and may be unpractical for e.g. embedded or mobile use case. For this I implemented a standalone, lightweight java lib (passing all of the RFC 5869 test vectors), which works with any javax.crypto.Mac instance:

https://github.com/patrickfav/hkdf

如果您愿意，您当然可以自行实施，这是一个相当直接的规范，当使用内置的JCA Hmac实现时。

If you prefer, you could, of course implement it on your own, it's a fairly straight forward spec, when using the built-in JCA Hmac implementation.

来自：

所以例如，如果您想从相同的源材料派生密钥和IV，您将使用info参数（）：

So for example if you want to derive an Secret Key and IV from the same source material you would use the info parameter (using this lib):

//example input
String userInput = "this is a user input with bad entropy";

HKDF hkdf = HKDF.fromHmacSha256();

//extract the "raw" data to create output with concentrated entropy
byte[] pseudoRandomKey = hkdf.extract(staticSalt32Byte, userInput.getBytes(StandardCharsets.UTF_8));

//create expanded bytes for e.g. AES secret key and IV
byte[] expandedAesKey = hkdf.expand(pseudoRandomKey, "aes-key".getBytes(StandardCharsets.UTF_8), 16);
byte[] expandedIv = hkdf.expand(pseudoRandomKey, "aes-iv".getBytes(StandardCharsets.UTF_8), 16);

//Example boilerplate encrypting a simple string with created key/iv
SecretKey key = new SecretKeySpec(expandedAesKey, "AES"); //AES-128 key
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(expandedIv));
byte[] encrypted = cipher.doFinal("my secret message".getBytes(StandardCharsets.UTF_8));

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