1 files changed, 263 insertions, 0 deletions
diff --git a/src/crypto/impl/bcrypt.c b/src/crypto/impl/bcrypt.c
new file mode 100644
index 0000000..9b01cac
--- /dev/null
+++ b/src/crypto/impl/bcrypt.c
@@ -0,0 +1,263 @@
+/*
+* Copyright (c) 2024 Vaughn Nugent
+*
+* Package: noscrypt
+* File: impl/bcrypt.c
+*
+* This library is free software; you can redistribute it and/or
+* modify it under the terms of the GNU Lesser General Public License
+* as published by the Free Software Foundation; either version 2.1
+* of the License, or  (at your option) any later version.
+*
+* This library is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public License
+* along with noscrypt. If not, see http://www.gnu.org/licenses/.
+*/
+
+
+/*
+*	This file provides as many fallback implementations on Windows plaforms
+*	as possible using the bcrypt library. This file should be included behind
+*	other libarry implementations, as it is a fallback.
+*/
+
+#ifdef _NC_IS_WINDOWS
+
+#define WIN32_LEAN_AND_MEAN
+#include <Windows.h>
+#include <bcrypt.h>
+
+#include "nc-util.h"
+#include "hkdf.h"
+
+#define IF_BC_FAIL(x) if(!BCRYPT_SUCCESS(x)) 
+#define BC_FAIL(x) if(!BCRYPT_SUCCESS(x)) return CSTATUS_FAIL;
+
+struct _bcrypt_ctx
+{
+	BCRYPT_ALG_HANDLE hAlg;
+	BCRYPT_HASH_HANDLE hHash;
+};
+
+_IMPLSTB NTSTATUS _bcInitSha256(struct _bcrypt_ctx* ctx, DWORD flags)
+{
+	NTSTATUS result;
+
+	result = BCryptOpenAlgorithmProvider(
+		&ctx->hAlg, 
+		BCRYPT_SHA256_ALGORITHM, 
+		NULL, 
+		flags
+	);
+
+	/*
+	*  If operation failed, ensure the algorithm handle is null
+	* to make free code easier to cleanup
+	*/
+	if (!BCRYPT_SUCCESS(result))
+	{
+		ctx->hAlg = NULL;
+	}
+
+	return result;
+}
+
+_IMPLSTB NTSTATUS _bcCreateHmac(struct _bcrypt_ctx* ctx, const cspan_t* key)
+{
+	/*
+	 * NOTE: 
+	 * I am not explicitly managing the update object buffer. By setting 
+	 * the update object to NULL, and length to 0, the buffer will be
+	 * managed by the bcrypt library.
+	 * 
+	 * See: https://learn.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptcreatehash
+	 */
+
+	return BCryptCreateHash(
+		ctx->hAlg, 
+		&ctx->hHash, 
+		NULL, 
+		0, 
+		(uint8_t*)key->data, 
+		key->size, 
+		BCRYPT_HASH_REUSABLE_FLAG	/* Enable reusable for expand function */
+	);
+}
+
+_IMPLSTB NTSTATUS _bcCreate(struct _bcrypt_ctx* ctx)
+{
+	cspan_t key;
+	
+	/* Zero out key span for 0 size and NULL data ptr */
+	SecureZeroMemory(&key, sizeof(cspan_t));
+
+	return _bcCreateHmac(ctx, &key);
+}
+
+_IMPLSTB NTSTATUS _bcHashDataRaw(const struct _bcrypt_ctx* ctx, const uint8_t* data, uint32_t len)
+{
+	return BCryptHashData(ctx->hHash, (uint8_t*)data, len, 0);
+}
+
+_IMPLSTB NTSTATUS _bcHashData(const struct _bcrypt_ctx* ctx, const cspan_t* data)
+{
+	return _bcHashDataRaw(ctx, data->data, data->size);
+}
+
+_IMPLSTB NTSTATUS _bcFinishHash(const struct _bcrypt_ctx* ctx, sha256_t digestOut32)
+{
+	return BCryptFinishHash(ctx->hHash, digestOut32, sizeof(sha256_t), 0);
+}
+
+_IMPLSTB void _bcDestroyCtx(struct _bcrypt_ctx* ctx)
+{
+	/* Free the update memory if it was allocated */
+	if(ctx->hHash) BCryptDestroyHash(ctx->hHash);
+	
+	/* Close the algorithm provider */
+	if (ctx->hAlg) BCryptCloseAlgorithmProvider(ctx->hAlg, 0);
+
+	ctx->hAlg = NULL;
+	ctx->hHash = NULL;
+}
+
+#ifndef _IMPL_SECURE_ZERO_MEMSET
+	/*
+	* On Windows, we can use SecureZeroMemory
+	* as platform zeroing function.
+	*
+	* NOTE:
+	* SecureZeroMemory2 uses volitle function argument
+	* pointers, which is a contested mehtod of compiler
+	* optimization prevention. GNU seems to oppose this method
+	*
+	* https://learn.microsoft.com/en-us/windows/win32/memory/winbase-securezeromemory2
+	*/
+	#define _IMPL_SECURE_ZERO_MEMSET SecureZeroMemory
+#endif /* !_IMPL_SECURE_ZERO_MEMSET */
+
+/*
+* Provide win32 fallback for sha256 digest if needed
+*/
+
+#ifndef _IMPL_CRYPTO_SHA256_DIGEST
+	
+	/* Export function fallack */
+	#define _IMPL_CRYPTO_SHA256_DIGEST			_bcrypt_sha256_digest	
+
+	_IMPLSTB cstatus_t _bcrypt_sha256_digest(const cspan_t* data, sha256_t digestOut32)
+	{
+		cstatus_t result;
+		struct _bcrypt_ctx ctx;
+
+		result = CSTATUS_FAIL;	/* Start in fail state */
+
+		IF_BC_FAIL(_bcInitSha256(&ctx, 0)) goto Exit;
+
+		IF_BC_FAIL(_bcCreate(&ctx)) goto Exit;
+
+		IF_BC_FAIL(_bcHashData(&ctx, data)) goto Exit;
+	
+		IF_BC_FAIL(_bcFinishHash(&ctx, digestOut32)) goto Exit;
+
+		result = CSTATUS_OK;	/* Hash operation completed, so set success */
+
+	Exit:
+
+		_bcDestroyCtx(&ctx);
+
+		return result;
+	}
+
+#endif /* !_IMPL_CRYPTO_SHA256_DIGEST */
+
+#ifndef _IMPL_CRYPTO_SHA256_HMAC
+
+	/* Export function */
+	#define _IMPL_CRYPTO_SHA256_HMAC				_bcrypt_hmac_sha256	
+	
+	_IMPLSTB cstatus_t _bcrypt_hmac_sha256(const cspan_t* key, const cspan_t* data, sha256_t hmacOut32)
+	{
+		cstatus_t result;
+		struct _bcrypt_ctx ctx;
+
+		result = CSTATUS_FAIL;		/* Start in fail state */
+
+		/* Init context with hmac flag set */
+		IF_BC_FAIL(_bcInitSha256(&ctx, BCRYPT_ALG_HANDLE_HMAC_FLAG)) goto Exit;
+
+		IF_BC_FAIL(_bcCreateHmac(&ctx, key)) goto Exit;
+
+		IF_BC_FAIL(_bcHashData(&ctx, data)) goto Exit;
+
+		IF_BC_FAIL(_bcFinishHash(&ctx, hmacOut32)) goto Exit;
+
+		result = CSTATUS_OK;	/* HMAC operation completed, so set success */
+
+	Exit:
+		
+		_bcDestroyCtx(&ctx);
+
+		return result;
+	}
+
+#endif /* !_IMPL_CRYPTO_SHA256_HMAC */
+
+/*
+* Provide a fallback HKDF expand function using the
+* HMAC function as a base.
+*/
+
+#ifndef _IMPL_CRYPTO_SHA256_HKDF_EXPAND
+
+	#define _IMPL_CRYPTO_SHA256_HKDF_EXPAND		_bcrypt_fallback_hkdf_expand
+
+	cstatus_t _bcrypt_hkdf_update(void* ctx, const cspan_t* data)
+	{
+		DEBUG_ASSERT(ctx != NULL)
+
+		BC_FAIL(_bcHashData((struct _bcrypt_ctx*)ctx, data))
+		return CSTATUS_OK;
+	}
+
+	cstatus_t _bcrypt_hkdf_finish(void* ctx, sha256_t hmacOut32)
+	{
+		DEBUG_ASSERT(ctx != NULL)
+
+		BC_FAIL(_bcFinishHash((struct _bcrypt_ctx*)ctx, hmacOut32))
+		return CSTATUS_OK;
+	}
+
+	_IMPLSTB cstatus_t _bcrypt_fallback_hkdf_expand(const cspan_t* prk, const cspan_t* info, span_t* okm)
+	{
+		cstatus_t result;
+		struct _bcrypt_ctx ctx;
+		struct nc_hkdf_fn_cb_struct handler;
+
+		handler.update = _bcrypt_hkdf_update;
+		handler.finish = _bcrypt_hkdf_finish;
+
+		/* Init bcrypt */
+		BC_FAIL(_bcInitSha256(&ctx, BCRYPT_ALG_HANDLE_HMAC_FLAG))
+
+		BC_FAIL(_bcCreateHmac(&ctx, prk))
+
+		/*
+		* NOTE! Hmac reusable flag must be set to allow for multiple
+		* calls to the finish function without losing the context.
+		*/
+
+		result = hkdfExpandProcess(&handler, &ctx, info, okm);
+
+		_bcDestroyCtx(&ctx);
+
+		return result;
+	}
+
+#endif /* !_IMPL_CRYPTO_SHA256_HKDF_EXPAND */
+
+#endif /* _NC_IS_WINDOWS */
+\ No newline at end of file