1 // Copyright 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 #ifndef _ROM_HMAC_H_
16 #define _ROM_HMAC_H_
17 
18 #ifdef __cplusplus
19 extern "C" {
20 #endif
21 
22 #include <stdint.h>
23 #include <stdlib.h>
24 #include "efuse.h"
25 
26 void ets_hmac_enable(void);
27 
28 void ets_hmac_disable(void);
29 
30 /* Use the "upstream" HMAC key (ETS_EFUSE_KEY_PURPOSE_HMAC_UP)
31    to digest a message.
32 */
33 int ets_hmac_calculate_message(ets_efuse_block_t key_block, const void *message, size_t message_len, uint8_t *hmac);
34 
35 /* Calculate a downstream HMAC message to temporarily enable JTAG, or
36    to generate a Digital Signature data decryption key.
37 
38    - purpose must be ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_DIGITAL_SIGNATURE
39      or ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_JTAG
40 
41    - key_block must be in range ETS_EFUSE_BLOCK_KEY0 toETS_EFUSE_BLOCK_KEY6.
42      This efuse block must have the corresponding purpose set in "purpose", or
43      ETS_EFUSE_KEY_PURPOSE_HMAC_DOWN_ALL.
44 
45    The result of this HMAC calculation is only made available "downstream" to the
46    corresponding hardware module, and cannot be accessed by software.
47 */
48 int ets_hmac_calculate_downstream(ets_efuse_block_t key_block, ets_efuse_purpose_t purpose);
49 
50 /* Invalidate a downstream HMAC value previously calculated by ets_hmac_calculate_downstream().
51  *
52  * - purpose must match a previous call to ets_hmac_calculate_downstream().
53  *
54  * After this function is called, the corresponding internal operation (JTAG or DS) will no longer
55  * have access to the generated key.
56  */
57 int ets_hmac_invalidate_downstream(ets_efuse_purpose_t purpose);
58 
59 #ifdef __cplusplus
60 }
61 #endif
62 
63 #endif // _ROM_HMAC_H_
64