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Roland Mikheldavidvincze
Roland Mikhel
authored and
davidvincze
committed
bootutil: Replace hash with SHA384 when P384 is used
Currently all the hashing functionality is done with SHA256 but if we would like to use ECDSA-P384 that requires SHA384 as the hashing algorithm, but MCUboot is using SHA256 for image hashing and public key hashing. This commit modifies the hashing operations to use SHA384 thus SHA256 can be omitted which is beneficial from a code size standpoint. Signed-off-by: Roland Mikhel <roland.mikhel@arm.com> Change-Id: I59230f76f88e0b42ad6383b2c9b71b73f33d7dd7
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7 files changed

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-95
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7 files changed

+115
-95
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‎boot/bootutil/include/bootutil/crypto/sha256.h ‎boot/bootutil/include/bootutil/crypto/sha.h

+54-36
Original file line numberDiff line numberDiff line change
@@ -18,8 +18,8 @@
1818
* the MCUBOOT_USE_PSA_CRYPTO will take precedence.
1919
*/
2020

21-
#ifndef __BOOTUTIL_CRYPTO_SHA256_H_
22-
#define __BOOTUTIL_CRYPTO_SHA256_H_
21+
#ifndef __BOOTUTIL_CRYPTO_SHA_H_
22+
#define __BOOTUTIL_CRYPTO_SHA_H_
2323

2424
#include "mcuboot_config/mcuboot_config.h"
2525
#include "mcuboot_config/mcuboot_logging.h"
@@ -34,8 +34,16 @@
3434
#error "One crypto backend must be defined: either CC310/MBED_TLS/TINYCRYPT/PSA_CRYPTO"
3535
#endif
3636

37+
#if defined(MCUBOOT_SIGN_EC384)
38+
#define IMAGE_HASH_SIZE (48)
39+
#define EXPECTED_HASH_TLV IMAGE_TLV_SHA384
40+
#else
41+
#define IMAGE_HASH_SIZE (32)
42+
#define EXPECTED_HASH_TLV IMAGE_TLV_SHA256
43+
#endif /* MCUBOOT_SIGN_EC384 */
44+
3745
/* Universal defines for SHA-256 */
38-
#define BOOTUTIL_CRYPTO_SHA256_BLOCK_SIZE (64)
46+
#define BOOTUTIL_CRYPTO_SHA256_BLOCK_SIZE (64)
3947
#define BOOTUTIL_CRYPTO_SHA256_DIGEST_SIZE (32)
4048

4149
#if defined(MCUBOOT_USE_PSA_CRYPTO)
@@ -69,119 +77,129 @@ extern "C" {
6977

7078
#if defined(MCUBOOT_USE_PSA_CRYPTO)
7179

72-
typedef psa_hash_operation_t bootutil_sha256_context;
80+
typedef psa_hash_operation_t bootutil_sha_context;
7381

74-
static inline int bootutil_sha256_init(bootutil_sha256_context *ctx)
82+
static inline int bootutil_sha_init(bootutil_sha_context *ctx)
7583
{
7684
*ctx = psa_hash_operation_init();
77-
return (int)psa_hash_setup(ctx, PSA_ALG_SHA_256);
85+
#if defined(MCUBOOT_SIGN_EC384)
86+
psa_status_t status = psa_hash_setup(ctx, PSA_ALG_SHA_384);
87+
#else
88+
psa_status_t status = psa_hash_setup(ctx, PSA_ALG_SHA_256);
89+
#endif
90+
return (int)status;
7891
}
7992

80-
static inline int bootutil_sha256_drop(bootutil_sha256_context *ctx)
93+
static inline int bootutil_sha_drop(bootutil_sha_context *ctx)
8194
{
8295
return (int)psa_hash_abort(ctx);
8396
}
8497

85-
static inline int bootutil_sha256_update(bootutil_sha256_context *ctx,
86-
const void *data,
87-
uint32_t data_len)
98+
static inline int bootutil_sha_update(bootutil_sha_context *ctx,
99+
const void *data,
100+
uint32_t data_len)
88101
{
89102
return (int)psa_hash_update(ctx, data, data_len);
90103
}
91104

92-
static inline int bootutil_sha256_finish(bootutil_sha256_context *ctx,
93-
uint8_t *output)
105+
static inline int bootutil_sha_finish(bootutil_sha_context *ctx,
106+
uint8_t *output)
94107
{
95108
size_t hash_length = 0;
96109
/* Assumes the output buffer is at least the expected size of the hash */
110+
#if defined(MCUBOOT_SIGN_EC384)
111+
return (int)psa_hash_finish(ctx, output, PSA_HASH_LENGTH(PSA_ALG_SHA_384), &hash_length);
112+
#else
97113
return (int)psa_hash_finish(ctx, output, PSA_HASH_LENGTH(PSA_ALG_SHA_256), &hash_length);
114+
#endif
98115
}
99116

100117
#elif defined(MCUBOOT_USE_MBED_TLS)
101118

102-
typedef mbedtls_sha256_context bootutil_sha256_context;
119+
typedef mbedtls_sha256_context bootutil_sha_context;
103120

104-
static inline int bootutil_sha256_init(bootutil_sha256_context *ctx)
121+
static inline int bootutil_sha_init(bootutil_sha_context *ctx)
105122
{
106123
mbedtls_sha256_init(ctx);
107124
return mbedtls_sha256_starts_ret(ctx, 0);
108125
}
109126

110-
static inline int bootutil_sha256_drop(bootutil_sha256_context *ctx)
127+
static inline int bootutil_sha_drop(bootutil_sha_context *ctx)
111128
{
112129
/* XXX: config defines MBEDTLS_PLATFORM_NO_STD_FUNCTIONS so no need to free */
113130
/* (void)mbedtls_sha256_free(ctx); */
114131
(void)ctx;
115132
return 0;
116133
}
117134

118-
static inline int bootutil_sha256_update(bootutil_sha256_context *ctx,
119-
const void *data,
120-
uint32_t data_len)
135+
static inline int bootutil_sha_update(bootutil_sha_context *ctx,
136+
const void *data,
137+
uint32_t data_len)
121138
{
122139
return mbedtls_sha256_update_ret(ctx, data, data_len);
123140
}
124141

125-
static inline int bootutil_sha256_finish(bootutil_sha256_context *ctx,
126-
uint8_t *output)
142+
static inline int bootutil_sha_finish(bootutil_sha_context *ctx,
143+
uint8_t *output)
127144
{
128145
return mbedtls_sha256_finish_ret(ctx, output);
129146
}
130147

131148
#endif /* MCUBOOT_USE_MBED_TLS */
132149

133150
#if defined(MCUBOOT_USE_TINYCRYPT)
134-
typedef struct tc_sha256_state_struct bootutil_sha256_context;
135-
static inline int bootutil_sha256_init(bootutil_sha256_context *ctx)
151+
typedef struct tc_sha256_state_struct bootutil_sha_context;
152+
153+
static inline int bootutil_sha_init(bootutil_sha_context *ctx)
136154
{
137155
tc_sha256_init(ctx);
138156
return 0;
139157
}
140158

141-
static inline int bootutil_sha256_drop(bootutil_sha256_context *ctx)
159+
static inline int bootutil_sha_drop(bootutil_sha_context *ctx)
142160
{
143161
(void)ctx;
144162
return 0;
145163
}
146164

147-
static inline int bootutil_sha256_update(bootutil_sha256_context *ctx,
148-
const void *data,
149-
uint32_t data_len)
165+
static inline int bootutil_sha_update(bootutil_sha_context *ctx,
166+
const void *data,
167+
uint32_t data_len)
150168
{
151169
return tc_sha256_update(ctx, data, data_len);
152170
}
153171

154-
static inline int bootutil_sha256_finish(bootutil_sha256_context *ctx,
155-
uint8_t *output)
172+
static inline int bootutil_sha_finish(bootutil_sha_context *ctx,
173+
uint8_t *output)
156174
{
157175
return tc_sha256_final(output, ctx);
158176
}
159177
#endif /* MCUBOOT_USE_TINYCRYPT */
160178

161179
#if defined(MCUBOOT_USE_CC310)
162-
static inline int bootutil_sha256_init(bootutil_sha256_context *ctx)
180+
static inline int bootutil_sha_init(bootutil_sha_context *ctx)
163181
{
164182
cc310_sha256_init(ctx);
165183
return 0;
166184
}
167185

168-
static inline int bootutil_sha256_drop(bootutil_sha256_context *ctx)
186+
static inline int bootutil_sha_drop(bootutil_sha_context *ctx)
169187
{
170188
(void)ctx;
171189
nrf_cc310_disable();
172190
return 0;
173191
}
174192

175-
static inline int bootutil_sha256_update(bootutil_sha256_context *ctx,
176-
const void *data,
177-
uint32_t data_len)
193+
static inline int bootutil_sha_update(bootutil_sha_context *ctx,
194+
const void *data,
195+
uint32_t data_len)
178196
{
179197
cc310_sha256_update(ctx, data, data_len);
180198
return 0;
181199
}
182200

183-
static inline int bootutil_sha256_finish(bootutil_sha256_context *ctx,
184-
uint8_t *output)
201+
static inline int bootutil_sha_finish(bootutil_sha_context *ctx,
202+
uint8_t *output)
185203
{
186204
cc310_sha256_finalize(ctx, output);
187205
return 0;
@@ -192,4 +210,4 @@ static inline int bootutil_sha256_finish(bootutil_sha256_context *ctx,
192210
}
193211
#endif
194212

195-
#endif /* __BOOTUTIL_CRYPTO_SHA256_H_ */
213+
#endif /* __BOOTUTIL_CRYPTO_SHA_H_ */

‎boot/bootutil/include/bootutil/image.h

+1-1
Original file line numberDiff line numberDiff line change
@@ -80,7 +80,6 @@ struct flash_area;
8080
* Image trailer TLV types.
8181
*
8282
* Signature is generated by computing signature over the image hash.
83-
* Currently the only image hash type is SHA256.
8483
*
8584
* Signature comes in the form of 2 TLVs.
8685
* 1st on identifies the public key which should be used to verify it.
@@ -89,6 +88,7 @@ struct flash_area;
8988
#define IMAGE_TLV_KEYHASH 0x01 /* hash of the public key */
9089
#define IMAGE_TLV_PUBKEY 0x02 /* public key */
9190
#define IMAGE_TLV_SHA256 0x10 /* SHA256 of image hdr and body */
91+
#define IMAGE_TLV_SHA384 0x11 /* SHA384 of image hdr and body */
9292
#define IMAGE_TLV_RSA2048_PSS 0x20 /* RSA2048 of hash output */
9393
#define IMAGE_TLV_ECDSA224 0x21 /* ECDSA of hash output - Not supported anymore */
9494
#define IMAGE_TLV_ECDSA_SIG 0x22 /* ECDSA of hash output */

‎boot/bootutil/src/boot_record.c

+4-3
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
/*
2-
* Copyright (c) 2018-2021 Arm Limited
2+
* Copyright (c) 2018-2023 Arm Limited
33
* Copyright (c) 2020 Linaro Limited
44
* Copyright (c) 2023, Nordic Semiconductor ASA
55
*
@@ -23,6 +23,7 @@
2323
#include <string.h>
2424

2525
#include "mcuboot_config/mcuboot_config.h"
26+
#include "bootutil/crypto/sha.h"
2627

2728
#if defined(MCUBOOT_MEASURED_BOOT) || defined(MCUBOOT_DATA_SHARING)
2829
#include "bootutil/boot_record.h"
@@ -127,7 +128,7 @@ boot_save_boot_status(uint8_t sw_module,
127128
uint16_t type;
128129
uint16_t ias_minor;
129130
size_t record_len = 0;
130-
uint8_t image_hash[32]; /* SHA256 - 32 Bytes */
131+
uint8_t image_hash[IMAGE_HASH_SIZE];
131132
uint8_t buf[MAX_BOOT_RECORD_SZ];
132133
bool boot_record_found = false;
133134
bool hash_found = false;
@@ -165,7 +166,7 @@ boot_save_boot_status(uint8_t sw_module,
165166
record_len = len;
166167
boot_record_found = true;
167168

168-
} else if (type == IMAGE_TLV_SHA256) {
169+
} else if (type == EXPECTED_HASH_TLV) {
169170
/* Get the image's hash value from the manifest section. */
170171
if (len > sizeof(image_hash)) {
171172
return -1;

‎boot/bootutil/src/encrypted.c

+1-1
Original file line numberDiff line numberDiff line change
@@ -30,7 +30,7 @@
3030
#endif
3131

3232
#if defined(MCUBOOT_ENCRYPT_EC256) || defined(MCUBOOT_ENCRYPT_X25519)
33-
#include "bootutil/crypto/sha256.h"
33+
#include "bootutil/crypto/sha.h"
3434
#include "bootutil/crypto/hmac_sha256.h"
3535
#include "mbedtls/oid.h"
3636
#include "mbedtls/asn1.h"

‎boot/bootutil/src/image_rsa.c

+14-14
Original file line numberDiff line numberDiff line change
@@ -43,7 +43,7 @@
4343
*/
4444
#if !defined(MCUBOOT_USE_PSA_CRYPTO)
4545

46-
#include "bootutil/crypto/sha256.h"
46+
#include "bootutil/crypto/sha.h"
4747

4848
/*
4949
* Constants for this particular constrained implementation of
@@ -86,17 +86,17 @@ static const uint8_t pss_zeros[8] = {0};
8686
static void
8787
pss_mgf1(uint8_t *mask, const uint8_t *hash)
8888
{
89-
bootutil_sha256_context ctx;
89+
bootutil_sha_context ctx;
9090
uint8_t counter[4] = { 0, 0, 0, 0 };
9191
uint8_t htmp[PSS_HLEN];
9292
int count = PSS_MASK_LEN;
9393
int bytes;
9494

9595
while (count > 0) {
96-
bootutil_sha256_init(&ctx);
97-
bootutil_sha256_update(&ctx, hash, PSS_HLEN);
98-
bootutil_sha256_update(&ctx, counter, 4);
99-
bootutil_sha256_finish(&ctx, htmp);
96+
bootutil_sha_init(&ctx);
97+
bootutil_sha_update(&ctx, hash, PSS_HLEN);
98+
bootutil_sha_update(&ctx, counter, 4);
99+
bootutil_sha_finish(&ctx, htmp);
100100

101101
counter[3]++;
102102

@@ -109,7 +109,7 @@ pss_mgf1(uint8_t *mask, const uint8_t *hash)
109109
count -= bytes;
110110
}
111111

112-
bootutil_sha256_drop(&ctx);
112+
bootutil_sha_drop(&ctx);
113113
}
114114

115115
/*
@@ -121,7 +121,7 @@ static fih_ret
121121
bootutil_cmp_rsasig(bootutil_rsa_context *ctx, uint8_t *hash, uint32_t hlen,
122122
uint8_t *sig, size_t slen)
123123
{
124-
bootutil_sha256_context shactx;
124+
bootutil_sha_context shactx;
125125
uint8_t em[MBEDTLS_MPI_MAX_SIZE];
126126
uint8_t db_mask[PSS_MASK_LEN];
127127
uint8_t h2[PSS_HLEN];
@@ -221,12 +221,12 @@ bootutil_cmp_rsasig(bootutil_rsa_context *ctx, uint8_t *hash, uint32_t hlen,
221221
/* Step 12. Let M' = 0x00 00 00 00 00 00 00 00 || mHash || salt; */
222222

223223
/* Step 13. Let H' = Hash(M') */
224-
bootutil_sha256_init(&shactx);
225-
bootutil_sha256_update(&shactx, pss_zeros, 8);
226-
bootutil_sha256_update(&shactx, hash, PSS_HLEN);
227-
bootutil_sha256_update(&shactx, &db_mask[PSS_MASK_SALT_POS], PSS_SLEN);
228-
bootutil_sha256_finish(&shactx, h2);
229-
bootutil_sha256_drop(&shactx);
224+
bootutil_sha_init(&shactx);
225+
bootutil_sha_update(&shactx, pss_zeros, 8);
226+
bootutil_sha_update(&shactx, hash, PSS_HLEN);
227+
bootutil_sha_update(&shactx, &db_mask[PSS_MASK_SALT_POS], PSS_SLEN);
228+
bootutil_sha_finish(&shactx, h2);
229+
bootutil_sha_drop(&shactx);
230230

231231
/* Step 14. If H = H', output "consistent". Otherwise, output
232232
* "inconsistent". */

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