diff --git a/dlls/bcrypt/bcrypt_main.c b/dlls/bcrypt/bcrypt_main.c
index 1b84ace8abe..b9c51a1f9fe 100644
--- a/dlls/bcrypt/bcrypt_main.c
+++ b/dlls/bcrypt/bcrypt_main.c
@@ -366,13 +366,17 @@ static NTSTATUS hash_finish( struct hash_impl *hash, enum alg_id alg_id,
     return STATUS_SUCCESS;
 }
 
+#define HASH_FLAG_HMAC      0x01
+#define HASH_FLAG_REUSABLE  0x02
 struct hash
 {
-    struct object    hdr;
-    enum alg_id      alg_id;
-    BOOL             hmac;
-    struct hash_impl outer;
-    struct hash_impl inner;
+    struct object     hdr;
+    enum alg_id       alg_id;
+    ULONG             flags;
+    UCHAR            *secret;
+    ULONG             secret_len;
+    struct hash_impl  outer;
+    struct hash_impl  inner;
 };
 
 #define BLOCK_LENGTH_AES        16
@@ -587,19 +591,45 @@ NTSTATUS WINAPI BCryptGetProperty( BCRYPT_HANDLE handle, LPCWSTR prop, UCHAR *bu
     }
 }
 
+static NTSTATUS prepare_hash( struct hash *hash )
+{
+    UCHAR buffer[MAX_HASH_BLOCK_BITS / 8] = {0};
+    int block_bytes, i;
+    NTSTATUS status;
+
+    /* initialize hash */
+    if ((status = hash_init( &hash->inner, hash->alg_id ))) return status;
+    if (!(hash->flags & HASH_FLAG_HMAC)) return STATUS_SUCCESS;
+
+    /* initialize hmac */
+    if ((status = hash_init( &hash->outer, hash->alg_id ))) return status;
+    block_bytes = alg_props[hash->alg_id].block_bits / 8;
+    if (hash->secret_len > block_bytes)
+    {
+        struct hash_impl temp;
+        if ((status = hash_init( &temp, hash->alg_id ))) return status;
+        if ((status = hash_update( &temp, hash->alg_id, hash->secret, hash->secret_len ))) return status;
+        if ((status = hash_finish( &temp, hash->alg_id, buffer,
+                                   alg_props[hash->alg_id].hash_length ))) return status;
+    }
+    else memcpy( buffer, hash->secret, hash->secret_len );
+
+    for (i = 0; i < block_bytes; i++) buffer[i] ^= 0x5c;
+    if ((status = hash_update( &hash->outer, hash->alg_id, buffer, block_bytes ))) return status;
+    for (i = 0; i < block_bytes; i++) buffer[i] ^= (0x5c ^ 0x36);
+    return hash_update( &hash->inner, hash->alg_id, buffer, block_bytes );
+}
+
 NTSTATUS WINAPI BCryptCreateHash( BCRYPT_ALG_HANDLE algorithm, BCRYPT_HASH_HANDLE *handle, UCHAR *object, ULONG objectlen,
                                   UCHAR *secret, ULONG secretlen, ULONG flags )
 {
     struct algorithm *alg = algorithm;
-    UCHAR buffer[MAX_HASH_BLOCK_BITS / 8] = {0};
     struct hash *hash;
-    int block_bytes;
     NTSTATUS status;
-    int i;
 
     TRACE( "%p, %p, %p, %u, %p, %u, %08x - stub\n", algorithm, handle, object, objectlen,
            secret, secretlen, flags );
-    if (flags)
+    if (flags & ~BCRYPT_HASH_REUSABLE_FLAG)
     {
         FIXME( "unimplemented flags %08x\n", flags );
         return STATUS_NOT_IMPLEMENTED;
@@ -608,38 +638,23 @@ NTSTATUS WINAPI BCryptCreateHash( BCRYPT_ALG_HANDLE algorithm, BCRYPT_HASH_HANDL
     if (!alg || alg->hdr.magic != MAGIC_ALG) return STATUS_INVALID_HANDLE;
     if (object) FIXME( "ignoring object buffer\n" );
 
-    if (!(hash = heap_alloc( sizeof(*hash) ))) return STATUS_NO_MEMORY;
+    if (!(hash = heap_alloc_zero( sizeof(*hash) ))) return STATUS_NO_MEMORY;
     hash->hdr.magic = MAGIC_HASH;
     hash->alg_id    = alg->id;
-    hash->hmac      = alg->hmac;
+    if (alg->hmac) hash->flags = HASH_FLAG_HMAC;
+    if (flags & BCRYPT_HASH_REUSABLE_FLAG) hash->flags |= HASH_FLAG_REUSABLE;
 
-    /* initialize hash */
-    if ((status = hash_init( &hash->inner, hash->alg_id ))) goto end;
-    if (!hash->hmac) goto end;
-
-    /* initialize hmac */
-    if ((status = hash_init( &hash->outer, hash->alg_id ))) goto end;
-    block_bytes = alg_props[hash->alg_id].block_bits / 8;
-    if (secretlen > block_bytes)
+    if (secretlen && !(hash->secret = heap_alloc( secretlen )))
     {
-        struct hash_impl temp;
-        if ((status = hash_init( &temp, hash->alg_id ))) goto end;
-        if ((status = hash_update( &temp, hash->alg_id, secret, secretlen ))) goto end;
-        if ((status = hash_finish( &temp, hash->alg_id, buffer,
-                                   alg_props[hash->alg_id].hash_length ))) goto end;
+        heap_free( hash );
+        return STATUS_NO_MEMORY;
     }
-    else
-    {
-        memcpy( buffer, secret, secretlen );
-    }
-    for (i = 0; i < block_bytes; i++) buffer[i] ^= 0x5c;
-    if ((status = hash_update( &hash->outer, hash->alg_id, buffer, block_bytes ))) goto end;
-    for (i = 0; i < block_bytes; i++) buffer[i] ^= (0x5c ^ 0x36);
-    status = hash_update( &hash->inner, hash->alg_id, buffer, block_bytes );
+    memcpy( hash->secret, secret, secretlen );
+    hash->secret_len = secretlen;
 
-end:
-    if (status != STATUS_SUCCESS)
+    if ((status = prepare_hash( hash )) != STATUS_SUCCESS)
     {
+        heap_free( hash->secret );
         heap_free( hash );
         return status;
     }
@@ -664,6 +679,12 @@ NTSTATUS WINAPI BCryptDuplicateHash( BCRYPT_HASH_HANDLE handle, BCRYPT_HASH_HAND
         return STATUS_NO_MEMORY;
 
     memcpy( hash_copy, hash_orig, sizeof(*hash_orig) );
+    if (hash_orig->secret && !(hash_copy->secret = heap_alloc( hash_orig->secret_len )))
+    {
+        heap_free( hash_copy );
+        return STATUS_NO_MEMORY;
+    }
+    memcpy( hash_copy->secret, hash_orig->secret, hash_orig->secret_len );
 
     *handle_copy = hash_copy;
     return STATUS_SUCCESS;
@@ -677,6 +698,7 @@ NTSTATUS WINAPI BCryptDestroyHash( BCRYPT_HASH_HANDLE handle )
 
     if (!hash || hash->hdr.magic != MAGIC_HASH) return STATUS_INVALID_PARAMETER;
     hash->hdr.magic = 0;
+    heap_free( hash->secret );
     heap_free( hash );
     return STATUS_SUCCESS;
 }
@@ -705,13 +727,19 @@ NTSTATUS WINAPI BCryptFinishHash( BCRYPT_HASH_HANDLE handle, UCHAR *output, ULON
     if (!hash || hash->hdr.magic != MAGIC_HASH) return STATUS_INVALID_HANDLE;
     if (!output) return STATUS_INVALID_PARAMETER;
 
-    if (!hash->hmac)
-        return hash_finish( &hash->inner, hash->alg_id, output, size );
+    if (!(hash->flags & HASH_FLAG_HMAC))
+    {
+        if ((status = hash_finish( &hash->inner, hash->alg_id, output, size ))) return status;
+        if (hash->flags & HASH_FLAG_REUSABLE) return prepare_hash( hash );
+        return STATUS_SUCCESS;
+    }
 
     hash_length = alg_props[hash->alg_id].hash_length;
     if ((status = hash_finish( &hash->inner, hash->alg_id, buffer, hash_length ))) return status;
     if ((status = hash_update( &hash->outer, hash->alg_id, buffer, hash_length ))) return status;
-    return hash_finish( &hash->outer, hash->alg_id, output, size );
+    if ((status = hash_finish( &hash->outer, hash->alg_id, output, size ))) return status;
+    if (hash->flags & HASH_FLAG_REUSABLE) return prepare_hash( hash );
+    return STATUS_SUCCESS;
 }
 
 NTSTATUS WINAPI BCryptHash( BCRYPT_ALG_HANDLE algorithm, UCHAR *secret, ULONG secretlen,
diff --git a/dlls/bcrypt/tests/bcrypt.c b/dlls/bcrypt/tests/bcrypt.c
index 5c1a9dc8340..a8bc43ce3db 100644
--- a/dlls/bcrypt/tests/bcrypt.c
+++ b/dlls/bcrypt/tests/bcrypt.c
@@ -221,7 +221,9 @@ struct hash_test
     const char *alg;
     unsigned hash_size;
     const char *hash;
+    const char *hash2;
     const char *hmac_hash;
+    const char *hmac_hash2;
 };
 
 static void test_hash(const struct hash_test *test)
@@ -269,6 +271,35 @@ static void test_hash(const struct hash_test *test)
     ret = pBCryptDestroyHash(hash);
     ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
 
+    hash = NULL;
+    len = sizeof(buf);
+    ret = pBCryptCreateHash(alg, &hash, buf, len, NULL, 0, BCRYPT_HASH_REUSABLE_FLAG);
+    ok(ret == STATUS_SUCCESS || broken(ret == STATUS_INVALID_PARAMETER) /* < win8 */, "got %08x\n", ret);
+    if (ret == STATUS_SUCCESS)
+    {
+        ret = pBCryptHashData(hash, (UCHAR *)"test", sizeof("test"), 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+
+        memset(hash_buf, 0, sizeof(hash_buf));
+        ret = pBCryptFinishHash(hash, hash_buf, test->hash_size, 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+        format_hash( hash_buf, test->hash_size, str );
+        ok(!strcmp(str, test->hash), "got %s\n", str);
+
+        /* reuse it */
+        ret = pBCryptHashData(hash, (UCHAR *)"tset", sizeof("tset"), 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+
+        memset(hash_buf, 0, sizeof(hash_buf));
+        ret = pBCryptFinishHash(hash, hash_buf, test->hash_size, 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+        format_hash( hash_buf, test->hash_size, str );
+        ok(!strcmp(str, test->hash2), "got %s\n", str);
+
+        ret = pBCryptDestroyHash(hash);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+    }
+
     ret = pBCryptCloseAlgorithmProvider(alg, 0);
     ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
 
@@ -298,6 +329,35 @@ static void test_hash(const struct hash_test *test)
     ret = pBCryptDestroyHash(hash);
     ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
 
+    hash = NULL;
+    len = sizeof(buf_hmac);
+    ret = pBCryptCreateHash(alg, &hash, buf_hmac, len, (UCHAR *)"key", sizeof("key"), BCRYPT_HASH_REUSABLE_FLAG);
+    ok(ret == STATUS_SUCCESS || broken(ret == STATUS_INVALID_PARAMETER) /* < win8 */, "got %08x\n", ret);
+    if (ret == STATUS_SUCCESS)
+    {
+        ret = pBCryptHashData(hash, (UCHAR *)"test", sizeof("test"), 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+
+        memset(hmac_hash, 0, sizeof(hmac_hash));
+        ret = pBCryptFinishHash(hash, hmac_hash, test->hash_size, 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+        format_hash( hmac_hash, test->hash_size, str );
+        ok(!strcmp(str, test->hmac_hash), "got %s\n", str);
+
+        /* reuse it */
+        ret = pBCryptHashData(hash, (UCHAR *)"tset", sizeof("tset"), 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+
+        memset(hmac_hash, 0, sizeof(hmac_hash));
+        ret = pBCryptFinishHash(hash, hmac_hash, test->hash_size, 0);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+        format_hash( hmac_hash, test->hash_size, str );
+        ok(!strcmp(str, test->hmac_hash2), "got %s\n", str);
+
+        ret = pBCryptDestroyHash(hash);
+        ok(ret == STATUS_SUCCESS, "got %08x\n", ret);
+    }
+
     ret = pBCryptDestroyHash(hash);
     ok(ret == STATUS_INVALID_PARAMETER, "got %08x\n", ret);
 
@@ -310,52 +370,57 @@ static void test_hash(const struct hash_test *test)
 
 static void test_hashes(void)
 {
-    static const struct hash_test tests[] = {
-        {
-            "SHA1",
-            20,
-            "961fa64958818f767707072755d7018dcd278e94",
-            "2472cf65d0e090618d769d3e46f0d9446cf212da"
+    static const struct hash_test tests[] =
+    {
+        { "SHA1", 20,
+        "961fa64958818f767707072755d7018dcd278e94",
+        "9314f62ff64197143c91fc86de37e9ae776a3fb8",
+        "2472cf65d0e090618d769d3e46f0d9446cf212da",
+        "b2d2ba8cfd714d474cf0d9622cc5d15e1f53d53f",
         },
-        {
-            "SHA256",
-            32,
-            "ceb73749c899693706ede1e30c9929b3fd5dd926163831c2fb8bd41e6efb1126",
-            "34c1aa473a4468a91d06e7cdbc75bc4f93b830ccfc2a47ffd74e8e6ed29e4c72"
+        { "SHA256", 32,
+        "ceb73749c899693706ede1e30c9929b3fd5dd926163831c2fb8bd41e6efb1126",
+        "ea0938c118a7b15954f41b85195f2b42aec3a9429c63f593cfa65c137ffaa986",
+        "34c1aa473a4468a91d06e7cdbc75bc4f93b830ccfc2a47ffd74e8e6ed29e4c72",
+        "55feb7052060bd99e33f36eb0982c7f4856eb6a84fbefe19a1afd9faafc3af6f",
         },
-        {
-            "SHA384",
-            48,
-            "62b21e90c9022b101671ba1f808f8631a8149f0f12904055839a35c1ca78ae53"
-            "63eed1e743a692d70e0504b0cfd12ef9",
-            "4b3e6d6ff2da121790ab7e7b9247583e3a7eed2db5bd4dabc680303b1608f37d"
-            "fdc836d96a704c03283bc05b4f6c5eb8"
+        { "SHA384", 48,
+        "62b21e90c9022b101671ba1f808f8631a8149f0f12904055839a35c1ca78ae53"
+        "63eed1e743a692d70e0504b0cfd12ef9",
+        "724db7c0bbc51ef1ac3fc793083fc54c0e5c423faec9b11378c01c236b19aaaf"
+        "a45177ad055feaf003968cc40ece44c7",
+        "4b3e6d6ff2da121790ab7e7b9247583e3a7eed2db5bd4dabc680303b1608f37d"
+        "fdc836d96a704c03283bc05b4f6c5eb8",
+        "03e1818e5c165a0e54619e513acb06c393e1a6cb0ddbb4036b5f29617b334642"
+        "e6e0be8b214d8508595b17a8c4b4e7db",
         },
-        {
-            "SHA512",
-            64,
-            "d55ced17163bf5386f2cd9ff21d6fd7fe576a915065c24744d09cfae4ec84ee1"
-            "ef6ef11bfbc5acce3639bab725b50a1fe2c204f8c820d6d7db0df0ecbc49c5ca",
-            "415fb6b10018ca03b38a1b1399c42ac0be5e8aceddb9a73103f5e543bf2d888f"
-            "2eecf91373941f9315dd730a77937fa92444450fbece86f409d9cb5ec48c6513"
+        { "SHA512", 64,
+        "d55ced17163bf5386f2cd9ff21d6fd7fe576a915065c24744d09cfae4ec84ee1"
+        "ef6ef11bfbc5acce3639bab725b50a1fe2c204f8c820d6d7db0df0ecbc49c5ca",
+        "7752d707b54d2b00e7d1c09120d189475b0fd2e31ebb988cf0a01fc8492ddc0b"
+        "3ca9c9ca61d9d7d1fb65ca7665e87f043c1d5bc9f786f8345e951c2d91ac594f",
+        "415fb6b10018ca03b38a1b1399c42ac0be5e8aceddb9a73103f5e543bf2d888f"
+        "2eecf91373941f9315dd730a77937fa92444450fbece86f409d9cb5ec48c6513",
+        "1487bcecba46ae677622fa499e4cb2f0fdf92f6f3427cba76382d537a06e49c3"
+        "3e70a2fc1fc730092bf21128c3704cc6387f6dfbf7e2f9f315bbb894505a1205",
         },
-        {
-            "MD2",
-            16,
-            "1bb33606ba908912a84221109d29cd7e",
-            "7f05b0638d77f4a27f3a9c4d353cd648"
+        { "MD2", 16,
+        "1bb33606ba908912a84221109d29cd7e",
+        "b9a6ad9323b17e2d0cd389dddd6ef78a",
+        "7f05b0638d77f4a27f3a9c4d353cd648",
+        "05980873e6bfdd05dd7b30078de7e42a",
         },
-        {
-            "MD4",
-            16,
-            "74b5db93c0b41e36ca7074338fc0b637",
-            "bc2e8ac4d8248ed21b8d26227a30ea3a"
+        { "MD4", 16,
+        "74b5db93c0b41e36ca7074338fc0b637",
+        "a14a9ff2059a8c28f47b01e6bc48a1bf",
+        "bc2e8ac4d8248ed21b8d26227a30ea3a",
+        "b609db0eb4b8669db74f2c20099701e4",
         },
-        {
-            "MD5",
-            16,
-            "e2a3e68d23ce348b8f68b3079de3d4c9",
-            "7bda029b93fa8d817fcc9e13d6bdf092"
+        { "MD5", 16,
+        "e2a3e68d23ce348b8f68b3079de3d4c9",
+        "bcdd7ca574342aa9db0e212348eacb16",
+        "7bda029b93fa8d817fcc9e13d6bdf092",
+        "dd636ab8e9592c5088e57c37d44c5bb3",
         }
     };
     unsigned i;
diff --git a/include/bcrypt.h b/include/bcrypt.h
index ba78c1d9d0b..a0b0d524956 100644
--- a/include/bcrypt.h
+++ b/include/bcrypt.h
@@ -222,6 +222,9 @@ typedef PVOID BCRYPT_HASH_HANDLE;
 /* Flags for BCryptEncrypt/BCryptDecrypt */
 #define BCRYPT_BLOCK_PADDING        0x00000001
 
+/* Flags for BCryptCreateHash */
+#define BCRYPT_HASH_REUSABLE_FLAG   0x00000020
+
 NTSTATUS WINAPI BCryptCloseAlgorithmProvider(BCRYPT_ALG_HANDLE, ULONG);
 NTSTATUS WINAPI BCryptCreateHash(BCRYPT_ALG_HANDLE, BCRYPT_HASH_HANDLE *, PUCHAR, ULONG, PUCHAR, ULONG, ULONG);
 NTSTATUS WINAPI BCryptDecrypt(BCRYPT_KEY_HANDLE, PUCHAR, ULONG, VOID *, PUCHAR, ULONG, PUCHAR, ULONG, ULONG *, ULONG);