1 // Copyright 2018-2020 Espressif Systems (Shanghai) PTE LTD
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //     http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 
15 #pragma once
16 
17 #ifdef __cplusplus
18 extern "C" {
19 #endif
20 
21 #include <stdint.h>
22 #include "efuse.h"
23 
24 void ets_hmac_enable(void);
25 
26 void ets_hmac_disable(void);
27 
28 /* Use the "upstream" HMAC key (ETS_EFUSE_KEY_PURPOSE_HMAC_UP)
29    to digest a message.
30 */
31 int ets_hmac_calculate_message(ets_efuse_block_t key_block, const void *message, size_t message_len, uint8_t *hmac);
32 
33 /* Calculate a downstream HMAC message to temporarily enable JTAG, or
34    to generate a Digital Signature data decryption key.
35 
36    - purpose must be ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_DIGITAL_SIGNATURE
37      or ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_JTAG
38 
39    - key_block must be in range ETS_EFUSE_BLOCK_KEY0 toETS_EFUSE_BLOCK_KEY6.
40      This efuse block must have the corresponding purpose set in "purpose", or
41      ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_ALL.
42 
43    The result of this HMAC calculation is only made available "downstream" to the
44    corresponding hardware module, and cannot be accessed by software.
45 */
46 int ets_hmac_calculate_downstream(ets_efuse_block_t key_block, ets_efuse_purpose_t purpose);
47 
48 /* Invalidate a downstream HMAC value previously calculated by ets_hmac_calculate_downstream().
49  *
50  * - purpose must match a previous call to ets_hmac_calculate_downstream().
51  *
52  * After this function is called, the corresponding internal operation (JTAG or DS) will no longer
53  * have access to the generated key.
54  */
55 int ets_hmac_invalidate_downstream(ets_efuse_purpose_t purpose);
56 
57 #ifdef __cplusplus
58 }
59 #endif
60