feat(hmac): add streaming context and generic pbkdf2

LimiNode · LimiNode · commit 8eade60b7973 · 2025-09-05T23:59:52.000+03:00
Introduce HmacContext with init, update and final methods. Implement the context in source, add a generic PBKDF2 buffer API, and extend tests.
diff --git a/include/hmac_cpp/hmac.hpp b/include/hmac_cpp/hmac.hpp
@@ -50,6 +50,36 @@ namespace hmac_cpp {
         return get_hash(input.data(), input.size(), type);
     }
 
+    /// \brief Streaming HMAC computation context.
+    class HmacContext {
+    public:
+        explicit HmacContext(TypeHash type) : type_(type), block_size_(0), digest_size_(0) {}
+
+        /// \brief Initializes the context with a secret key.
+        /// \param key_ptr Pointer to the key buffer; must be non-null if key_len > 0
+        /// \param key_len Length of the key in bytes
+        void init(const void* key_ptr, size_t key_len);
+
+        /// \brief Updates the HMAC with message data.
+        /// \param data_ptr Pointer to the message buffer; must be non-null if data_len > 0
+        /// \param data_len Length of the message in bytes
+        void update(const void* data_ptr, size_t data_len);
+
+        /// \brief Finalizes the HMAC and writes the result to the provided buffer.
+        /// \param out_ptr Output buffer for the HMAC result
+        /// \param out_len Length of the output buffer; must be at least the digest size
+        void final(uint8_t* out_ptr, size_t out_len);
+
+    private:
+        TypeHash type_;
+        size_t block_size_;
+        size_t digest_size_;
+        secure_buffer<uint8_t> okeypad_;
+        hmac_hash::SHA1 sha1_;
+        hmac_hash::SHA256 sha256_;
+        hmac_hash::SHA512 sha512_;
+    };
+
     /// \brief Computes HMAC for raw binary data using the specified hash function.
     /// \param key_ptr Pointer to the key buffer; must be non-null if key_len > 0
     /// \param key_len Length of the key in bytes
diff --git a/include/hmac_cpp/hmac_utils.hpp b/include/hmac_cpp/hmac_utils.hpp
@@ -106,6 +106,55 @@ namespace hmac_cpp {
                       iterations, dk_len, prf);
     }
 
+    /// \brief Derives PBKDF2 into caller-provided buffer using selected hash.
+    /// \param prf Hash function to use (SHA1, SHA256, SHA512)
+    /// \param password_ptr Pointer to the password buffer
+    /// \param password_len Length of the password in bytes
+    /// \param salt_ptr Pointer to the salt buffer
+    /// \param salt_len Length of the salt in bytes
+    /// \param iterations Number of iterations, must be positive
+    /// \param out_ptr Output buffer for derived key
+    /// \param dk_len Length of output buffer in bytes, must be positive
+    /// \return true on success, false on invalid parameters
+    bool pbkdf2(Pbkdf2Hash prf,
+                const void* password_ptr, size_t password_len,
+                const void* salt_ptr, size_t salt_len,
+                uint32_t iterations, uint8_t* out_ptr, size_t dk_len) noexcept;
+
+    /// \deprecated Use overloads that accept std::vector<uint8_t> or secure_buffer.
+    template<size_t N>
+    HMACCPP_DEPRECATED("use std::vector<uint8_t> or secure_buffer overload")
+    inline bool pbkdf2(Pbkdf2Hash prf,
+                       const std::string& password,
+                       const std::string& salt,
+                       uint32_t iterations,
+                       std::array<uint8_t, N>& out) noexcept {
+        return pbkdf2(prf, password.data(), password.size(),
+                      salt.data(), salt.size(),
+                      iterations, out.data(), out.size());
+    }
+
+    inline bool pbkdf2(Pbkdf2Hash prf,
+                       const secure_buffer<uint8_t>& password,
+                       const secure_buffer<uint8_t>& salt,
+                       uint32_t iterations,
+                       uint8_t* out_ptr, size_t dk_len) noexcept {
+        return pbkdf2(prf, password.data(), password.size(),
+                      salt.data(), salt.size(),
+                      iterations, out_ptr, dk_len);
+    }
+
+    template<size_t N>
+    inline bool pbkdf2(Pbkdf2Hash prf,
+                       const secure_buffer<uint8_t>& password,
+                       const secure_buffer<uint8_t>& salt,
+                       uint32_t iterations,
+                       std::array<uint8_t, N>& out) noexcept {
+        return pbkdf2(prf, password.data(), password.size(),
+                      salt.data(), salt.size(),
+                      iterations, out.data(), out.size());
+    }
+
     /// \brief Derives PBKDF2-HMAC-SHA256 into caller-provided buffer
     /// \param password_ptr Pointer to the password buffer
     /// \param password_len Length of the password in bytes
diff --git a/src/hmac.cpp b/src/hmac.cpp
@@ -86,6 +86,126 @@ namespace hmac_cpp {
         }
     }
 
+    void HmacContext::init(const void* key_ptr, size_t key_len) {
+        if (key_len > 0 && key_ptr == nullptr)
+            throw std::invalid_argument("Null key with non-zero length");
+
+        switch (type_) {
+            case TypeHash::SHA1:
+                block_size_ = hmac_hash::SHA1::BLOCK_SIZE;
+                digest_size_ = hmac_hash::SHA1::DIGEST_SIZE;
+                break;
+            case TypeHash::SHA256:
+                block_size_ = hmac_hash::SHA256::SHA224_256_BLOCK_SIZE;
+                digest_size_ = hmac_hash::SHA256::DIGEST_SIZE;
+                break;
+            case TypeHash::SHA512:
+                block_size_ = hmac_hash::SHA512::SHA384_512_BLOCK_SIZE;
+                digest_size_ = hmac_hash::SHA512::DIGEST_SIZE;
+                break;
+            default:
+                throw std::invalid_argument("Unsupported hash type");
+        }
+
+        secure_buffer<uint8_t> key(block_size_);
+        if (key_len > block_size_) {
+            auto hashed = get_hash(key_ptr, key_len, type_);
+            std::copy(hashed.begin(), hashed.end(), key.begin());
+            if (hashed.size() < block_size_)
+                std::fill(key.begin() + hashed.size(), key.end(), 0);
+            secure_zero(hashed.data(), hashed.size());
+        } else {
+            if (key_len > 0)
+                std::memcpy(key.data(), key_ptr, key_len);
+            if (key_len < block_size_)
+                std::fill(key.begin() + key_len, key.end(), 0);
+        }
+
+        okeypad_ = secure_buffer<uint8_t>(block_size_);
+        secure_buffer<uint8_t> ipad(block_size_);
+        for (size_t i = 0; i < block_size_; ++i) {
+            const uint8_t k = key[i];
+            ipad[i] = k ^ 0x36;
+            okeypad_[i] = k ^ 0x5c;
+        }
+
+        switch (type_) {
+            case TypeHash::SHA1:
+                sha1_.init();
+                sha1_.update(ipad.data(), block_size_);
+                break;
+            case TypeHash::SHA256:
+                sha256_.init();
+                sha256_.update(ipad.data(), block_size_);
+                break;
+            case TypeHash::SHA512:
+                sha512_.init();
+                sha512_.update(ipad.data(), block_size_);
+                break;
+            default:
+                throw std::invalid_argument("Unsupported hash type");
+        }
+
+        secure_zero(key.data(), key.size());
+        secure_zero(ipad.data(), ipad.size());
+    }
+
+    void HmacContext::update(const void* data_ptr, size_t data_len) {
+        if (data_len > 0 && data_ptr == nullptr)
+            throw std::invalid_argument("Null data pointer with non-zero length");
+        const uint8_t* p = static_cast<const uint8_t*>(data_ptr);
+        switch (type_) {
+            case TypeHash::SHA1:
+                sha1_.update(p, data_len);
+                break;
+            case TypeHash::SHA256:
+                sha256_.update(p, data_len);
+                break;
+            case TypeHash::SHA512:
+                sha512_.update(p, data_len);
+                break;
+            default:
+                throw std::invalid_argument("Unsupported hash type");
+        }
+    }
+
+    void HmacContext::final(uint8_t* out_ptr, size_t out_len) {
+        if (out_ptr == nullptr)
+            throw std::invalid_argument("Null output pointer");
+        if (out_len < digest_size_)
+            throw std::invalid_argument("Output buffer too small");
+
+        secure_buffer<uint8_t> inner(digest_size_);
+
+        switch (type_) {
+            case TypeHash::SHA1:
+                sha1_.finish(inner.data());
+                sha1_.init();
+                sha1_.update(okeypad_.data(), block_size_);
+                sha1_.update(inner.data(), digest_size_);
+                sha1_.finish(out_ptr);
+                break;
+            case TypeHash::SHA256:
+                sha256_.finish(inner.data());
+                sha256_.init();
+                sha256_.update(okeypad_.data(), block_size_);
+                sha256_.update(inner.data(), digest_size_);
+                sha256_.finish(out_ptr);
+                break;
+            case TypeHash::SHA512:
+                sha512_.finish(inner.data());
+                sha512_.init();
+                sha512_.update(okeypad_.data(), block_size_);
+                sha512_.update(inner.data(), digest_size_);
+                sha512_.finish(out_ptr);
+                break;
+            default:
+                throw std::invalid_argument("Unsupported hash type");
+        }
+
+        secure_zero(inner.data(), inner.size());
+    }
+
     std::vector<uint8_t> get_hmac(const void* key_ptr, size_t key_len, const void* msg_ptr, size_t msg_len, TypeHash type) {
         if ((key_len > 0 && key_ptr == nullptr) || (msg_len > 0 && msg_ptr == nullptr))
             throw std::invalid_argument("Null pointer with non-zero length");
diff --git a/src/hmac_utils.cpp b/src/hmac_utils.cpp
@@ -110,9 +110,10 @@ namespace hmac_cpp {
         return derived;
     }
 
-    bool pbkdf2_hmac_sha256(const void* password_ptr, size_t password_len,
-                            const void* salt_ptr, size_t salt_len,
-                            uint32_t iterations, uint8_t* out_ptr, size_t dk_len) noexcept {
+    bool pbkdf2(Pbkdf2Hash prf,
+                const void* password_ptr, size_t password_len,
+                const void* salt_ptr, size_t salt_len,
+                uint32_t iterations, uint8_t* out_ptr, size_t dk_len) noexcept {
         if ((password_len > 0 && password_ptr == nullptr) ||
             (salt_len > 0 && salt_ptr == nullptr) ||
             out_ptr == nullptr)
@@ -121,7 +122,22 @@ namespace hmac_cpp {
             iterations > MAX_PBKDF2_ITERATIONS)
             return false;
 
-        const size_t hlen = hmac_hash::SHA256::DIGEST_SIZE;
+        TypeHash hash_type = to_type_hash(prf);
+        size_t hlen = 0;
+        switch (hash_type) {
+            case TypeHash::SHA1:
+                hlen = hmac_hash::SHA1::DIGEST_SIZE;
+                break;
+            case TypeHash::SHA256:
+                hlen = hmac_hash::SHA256::DIGEST_SIZE;
+                break;
+            case TypeHash::SHA512:
+                hlen = hmac_hash::SHA512::DIGEST_SIZE;
+                break;
+            default:
+                return false;
+        }
+
         uint64_t max_dk = (static_cast<uint64_t>(1) << 32) - 1;
         max_dk *= hlen;
         if (dk_len > max_dk)
@@ -144,27 +160,44 @@ namespace hmac_cpp {
             salt_block[salt_len + 2] = static_cast<uint8_t>((i >> 8) & 0xFF);
             salt_block[salt_len + 3] = static_cast<uint8_t>(i & 0xFF);
 
-            secure_buffer<uint8_t> u(std::move(get_hmac(password_ptr, password_len,
-                                                         salt_block.data(), salt_block.size(),
-                                                         TypeHash::SHA256)));
-            secure_buffer<uint8_t> t = u;
+            secure_buffer<uint8_t> u(hlen);
+            secure_buffer<uint8_t> t(hlen);
+            HmacContext ctx(hash_type);
+            ctx.init(password_ptr, password_len);
+            ctx.update(salt_block.data(), salt_block.size());
+            ctx.final(u.data(), hlen);
+            std::memcpy(t.data(), u.data(), hlen);
+
             for (uint32_t j = 1; j < iterations; ++j) {
-                u = secure_buffer<uint8_t>(get_hmac(password_ptr, password_len,
-                                                    u.data(), u.size(), TypeHash::SHA256));
-                for (size_t k = 0; k < t.size(); ++k) {
+                ctx.init(password_ptr, password_len);
+                ctx.update(u.data(), hlen);
+                ctx.final(u.data(), hlen);
+                for (size_t k = 0; k < hlen; ++k) {
                     t[k] ^= u[k];
                 }
             }
+
             size_t take = (i == l) ? r : hlen;
             std::memcpy(out_ptr + pos, t.data(), take);
             pos += take;
+
             secure_zero(u.data(), u.size());
             secure_zero(t.data(), t.size());
         }
+
         secure_zero(salt_block.data(), salt_block.size());
         return true;
     }
 
+    bool pbkdf2_hmac_sha256(const void* password_ptr, size_t password_len,
+                            const void* salt_ptr, size_t salt_len,
+                            uint32_t iterations, uint8_t* out_ptr, size_t dk_len) noexcept {
+        return pbkdf2(Pbkdf2Hash::Sha256,
+                      password_ptr, password_len,
+                      salt_ptr, salt_len,
+                      iterations, out_ptr, dk_len);
+    }
+
     std::vector<uint8_t> pbkdf2_with_pepper(
             const void* password_ptr, size_t password_len,
             const void* salt_ptr, size_t salt_len,
diff --git a/test_all.cpp b/test_all.cpp
@@ -306,6 +306,17 @@ TEST(PBKDF2BufferApiTest, SHA256ArrayOutput) {
     EXPECT_TRUE(std::equal(out.begin(), out.end(), ref.begin()));
 }
 
+TEST(PBKDF2BufferApiTest, GenericArrayOutput) {
+    auto salt = from_hex("000102030405060708090a0b0c0d0e0f");
+    std::string salt_str(salt.begin(), salt.end());
+    std::array<uint8_t,32> out{};
+    ASSERT_TRUE(hmac::pbkdf2(hmac::Pbkdf2Hash::Sha256,
+                             std::string("password"), salt_str, 2, out));
+    std::vector<uint8_t> ref(32);
+    ASSERT_TRUE(PKCS5_PBKDF2_HMAC("password", 8, salt.data(), salt.size(), 2, EVP_sha256(), ref.size(), ref.data()));
+    EXPECT_TRUE(std::equal(out.begin(), out.end(), ref.begin()));
+}
+
 TEST(PBKDF2BufferApiTest, IterationsLimit) {
     std::string salt(16, 'a');
     std::array<uint8_t,32> out{};
