From 5f4061aec36082c3c263497b8397639dd7035407 Mon Sep 17 00:00:00 2001
From: lifegpc <root@lifegpc.com>
Date: Mon, 12 May 2025 18:18:32 +0800
Subject: [PATCH] add HMAC support

---
 hash_lib.h             | 64 ++++++++++++++++++++++++++++++++++++++++++
 test/hash_lib_test.cpp |  9 ++++++
 2 files changed, 73 insertions(+)

diff --git a/hash_lib.h b/hash_lib.h
index 1f15e7f..f42d93d 100644
--- a/hash_lib.h
+++ b/hash_lib.h
@@ -127,6 +127,70 @@ namespace hash_lib {
         size_t hashBlocks(const uint8_t* m, size_t pos, size_t len);
     };
     template<class H>
+    class HMAC: public Hash {
+    public:
+        HMAC(const uint8_t* key, size_t len) {
+            int blockSize = _outer.blockSize();
+            std::vector<uint8_t> pad(blockSize);
+            if (len > blockSize) {
+                _inner.update(key, len)->finish(pad)->clean();
+            } else {
+                memcpy(pad.data(), key, len);
+            }
+            _pad = std::move(pad);
+            reset();
+        }
+        HMAC(const std::string& key) : HMAC((const uint8_t*)key.c_str(), key.size()) {}
+        HMAC(const std::vector<uint8_t>& key) : HMAC(key.data(), key.size()) {}
+        template <size_t T>
+        HMAC(const uint8_t (&key)[T]) : HMAC(key, T) {}
+        Hash* reset() override {
+            _inner.clean();
+            _outer.clean();
+            int blockSize = _outer.blockSize();
+            auto pad(_pad);
+            for (int i = 0; i < blockSize; i++) {
+                pad[i] ^= 0x36;
+            }
+            _inner.update(pad);
+            for (int i = 0; i < blockSize; i++) {
+                pad[i] ^= 0x36 ^ 0x5c;
+            }
+            _outer.update(pad);
+            _finished = false;
+            return this;
+        }
+        int digestLength() override {
+            return _outer.digestLength();
+        }
+        int blockSize() override {
+            return _outer.blockSize();
+        }
+        Hash* update(const uint8_t* data, size_t len) override {
+            _inner.update(data, len);
+            return this;
+        }
+        using Hash::update;
+        Hash* finish(uint8_t* data, size_t len) override {
+            if (_finished) {
+                _outer.finish(data, len);
+                return this;
+            }
+            _outer.update(_inner.digest())->finish(data, len);
+            _finished = true;
+            return this;
+        }
+        using Hash::finish;
+        void clean() override {
+            reset();
+        }
+    private:
+        H _inner;
+        H _outer;
+        std::vector<uint8_t> _pad;
+        bool _finished = false; 
+    };
+    template<class H>
     std::vector<uint8_t> hash(const uint8_t* data, size_t len) {
         H h;
         h.update(data, len);
diff --git a/test/hash_lib_test.cpp b/test/hash_lib_test.cpp
index d9e92a1..f8748cb 100644
--- a/test/hash_lib_test.cpp
+++ b/test/hash_lib_test.cpp
@@ -48,3 +48,12 @@ TEST(HashLibTest, SHA1Test) {
     GTEST_ASSERT_EQ(hashHex<SHA1>("Hello, World!"), "0a0a9f2a6772942557ab5355d76af442f8f65e01");
     GTEST_ASSERT_EQ(hashHex<SHA1>("随便来一些中文。测试超过一百二十八字节时的状况。用于测试是否存在问题。还是不够长呢。啊啊啊。"), "21c05e3532d593ec382b8e361d43a17e8fb8774a");
 }
+
+TEST(HashLibTest, HMACClassTest) {
+    HMAC<SHA512> hmac("key");
+    hmac.update("Hello, World!");
+    GTEST_ASSERT_EQ(hmac.hexDigest(), "7b735ac190ebd1432d56f95ae2aea5a04a23128f4c228e299b7a49fb7561de8cc8f4fdf4486dc743dfd07827d617273aab42b3bf819d243ded322fac167419f1");
+    hmac.clean();
+    hmac.update("Hello, World!");
+    GTEST_ASSERT_EQ(hmac.hexDigest(), "7b735ac190ebd1432d56f95ae2aea5a04a23128f4c228e299b7a49fb7561de8cc8f4fdf4486dc743dfd07827d617273aab42b3bf819d243ded322fac167419f1");
+}