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ctr_drbg: add alternative PSA implementation when AES_C is not defined

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Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
This commit is contained in:
Valerio Setti 2023-11-13 10:18:16 +01:00
parent fbefe04bf3
commit 5f4b28defc
2 changed files with 164 additions and 2 deletions
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18
include/mbedtls/ctr_drbg.h
View file

@ -32,7 +32,14 @@
#include "mbedtls/build_info.h"
/* In case AES_C is defined then it is the primary option for backward
* compatibility purposes. If that's not available, PSA is used instead */
#if defined(MBEDTLS_AES_C)
#include "mbedtls/aes.h"
#else
#include "psa/crypto.h"
#endif
#include "entropy.h"
#if defined(MBEDTLS_THREADING_C)
@ -150,6 +157,13 @@ extern "C" {
#define MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN (MBEDTLS_CTR_DRBG_ENTROPY_LEN + 1) / 2
#endif
#if !defined(MBEDTLS_AES_C)
typedef struct mbedtls_ctr_drbg_psa_context {
mbedtls_svc_key_id_t key_id;
psa_cipher_operation_t operation;
} mbedtls_ctr_drbg_psa_context;
#endif
/**
* \brief The CTR_DRBG context structure.
*/
@ -175,7 +189,11 @@ typedef struct mbedtls_ctr_drbg_context {
* This is the maximum number of requests
* that can be made between reseedings. */
#if defined(MBEDTLS_AES_C)
mbedtls_aes_context MBEDTLS_PRIVATE(aes_ctx); /*!< The AES context. */
#else
mbedtls_ctr_drbg_psa_context MBEDTLS_PRIVATE(psa_ctx); /*!< The PSA context. */
#endif
/*
* Callbacks (Entropy)

148
library/ctr_drbg.c
View file

@ -24,15 +24,60 @@
#include <stdio.h>
#endif
/* Using error translation functions from PSA to MbedTLS */
#if !defined(MBEDTLS_AES_C)
#include "psa_util_internal.h"
#endif
#include "mbedtls/platform.h"
#if !defined(MBEDTLS_AES_C)
static psa_status_t ctr_drbg_setup_psa_context(mbedtls_ctr_drbg_psa_context *psa_ctx,
unsigned char *key, size_t key_len)
{
psa_key_attributes_t key_attr = PSA_KEY_ATTRIBUTES_INIT;
psa_status_t status;
psa_set_key_usage_flags(&key_attr, PSA_KEY_USAGE_ENCRYPT);
psa_set_key_algorithm(&key_attr, PSA_ALG_ECB_NO_PADDING);
psa_set_key_type(&key_attr, PSA_KEY_TYPE_AES);
status = psa_import_key(&key_attr, key, key_len, &psa_ctx->key_id);
if (status != PSA_SUCCESS) {
goto exit;
}
status = psa_cipher_encrypt_setup(&psa_ctx->operation, psa_ctx->key_id, PSA_ALG_ECB_NO_PADDING);
if (status != PSA_SUCCESS) {
goto exit;
}
exit:
psa_reset_key_attributes(&key_attr);
return status;
}
static void ctr_drbg_destroy_psa_contex(mbedtls_ctr_drbg_psa_context *psa_ctx)
{
psa_cipher_abort(&psa_ctx->operation);
psa_destroy_key(psa_ctx->key_id);
psa_ctx->operation = psa_cipher_operation_init();
psa_ctx->key_id = MBEDTLS_SVC_KEY_ID_INIT;
}
#endif
/*
* CTR_DRBG context initialization
*/
void mbedtls_ctr_drbg_init(mbedtls_ctr_drbg_context *ctx)
{
memset(ctx, 0, sizeof(mbedtls_ctr_drbg_context));
#if defined(MBEDTLS_AES_C)
mbedtls_aes_init(&ctx->aes_ctx);
#else
ctx->psa_ctx.key_id = MBEDTLS_SVC_KEY_ID_INIT;
ctx->psa_ctx.operation = psa_cipher_operation_init();
#endif
/* Indicate that the entropy nonce length is not set explicitly.
* See mbedtls_ctr_drbg_set_nonce_len(). */
ctx->reseed_counter = -1;
@ -56,7 +101,11 @@ void mbedtls_ctr_drbg_free(mbedtls_ctr_drbg_context *ctx)
mbedtls_mutex_free(&ctx->mutex);
}
#endif
#if defined(MBEDTLS_AES_C)
mbedtls_aes_free(&ctx->aes_ctx);
#else
ctr_drbg_destroy_psa_contex(&ctx->psa_ctx);
#endif
mbedtls_platform_zeroize(ctx, sizeof(mbedtls_ctr_drbg_context));
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
ctx->reseed_counter = -1;
@ -117,8 +166,17 @@ static int block_cipher_df(unsigned char *output,
unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
unsigned char chain[MBEDTLS_CTR_DRBG_BLOCKSIZE];
unsigned char *p, *iv;
mbedtls_aes_context aes_ctx;
int ret = 0;
#if defined(MBEDTLS_AES_C)
mbedtls_aes_context aes_ctx;
#else
psa_status_t status;
size_t tmp_len;
mbedtls_ctr_drbg_psa_context psa_ctx;
psa_ctx.key_id = MBEDTLS_SVC_KEY_ID_INIT;
psa_ctx.operation = psa_cipher_operation_init();
#endif
int i, j;
size_t buf_len, use_len;
@ -129,7 +187,6 @@ static int block_cipher_df(unsigned char *output,
memset(buf, 0, MBEDTLS_CTR_DRBG_MAX_SEED_INPUT +
MBEDTLS_CTR_DRBG_BLOCKSIZE + 16);
mbedtls_aes_init(&aes_ctx);
/*
* Construct IV (16 bytes) and S in buffer
@ -151,10 +208,20 @@ static int block_cipher_df(unsigned char *output,
key[i] = i;
}
#if defined(MBEDTLS_AES_C)
mbedtls_aes_init(&aes_ctx);
if ((ret = mbedtls_aes_setkey_enc(&aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS)) != 0) {
goto exit;
}
#else
status = ctr_drbg_setup_psa_context(&psa_ctx, key, sizeof(key));
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
/*
* Reduce data to MBEDTLS_CTR_DRBG_SEEDLEN bytes of data
@ -170,10 +237,19 @@ static int block_cipher_df(unsigned char *output,
use_len -= (use_len >= MBEDTLS_CTR_DRBG_BLOCKSIZE) ?
MBEDTLS_CTR_DRBG_BLOCKSIZE : use_len;
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_crypt_ecb(&aes_ctx, MBEDTLS_AES_ENCRYPT,
chain, chain)) != 0) {
goto exit;
}
#else
status = psa_cipher_update(&psa_ctx.operation, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE,
chain, MBEDTLS_CTR_DRBG_BLOCKSIZE, &tmp_len);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
}
memcpy(tmp + j, chain, MBEDTLS_CTR_DRBG_BLOCKSIZE);
@ -187,23 +263,46 @@ static int block_cipher_df(unsigned char *output,
/*
* Do final encryption with reduced data
*/
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_setkey_enc(&aes_ctx, tmp,
MBEDTLS_CTR_DRBG_KEYBITS)) != 0) {
goto exit;
}
#else
ctr_drbg_destroy_psa_contex(&psa_ctx);
status = ctr_drbg_setup_psa_context(&psa_ctx, tmp, MBEDTLS_CTR_DRBG_KEYSIZE);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
iv = tmp + MBEDTLS_CTR_DRBG_KEYSIZE;
p = output;
for (j = 0; j < MBEDTLS_CTR_DRBG_SEEDLEN; j += MBEDTLS_CTR_DRBG_BLOCKSIZE) {
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_crypt_ecb(&aes_ctx, MBEDTLS_AES_ENCRYPT,
iv, iv)) != 0) {
goto exit;
}
#else
status = psa_cipher_update(&psa_ctx.operation, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE,
iv, MBEDTLS_CTR_DRBG_BLOCKSIZE, &tmp_len);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
memcpy(p, iv, MBEDTLS_CTR_DRBG_BLOCKSIZE);
p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
}
exit:
#if defined(MBEDTLS_AES_C)
mbedtls_aes_free(&aes_ctx);
#else
ctr_drbg_destroy_psa_contex(&psa_ctx);
#endif
/*
* tidy up the stack
*/
@ -236,6 +335,10 @@ static int ctr_drbg_update_internal(mbedtls_ctr_drbg_context *ctx,
unsigned char *p = tmp;
int i, j;
int ret = 0;
#if !defined(MBEDTLS_AES_C)
psa_status_t status;
size_t tmp_len;
#endif
memset(tmp, 0, MBEDTLS_CTR_DRBG_SEEDLEN);
@ -252,10 +355,19 @@ static int ctr_drbg_update_internal(mbedtls_ctr_drbg_context *ctx,
/*
* Crypt counter block
*/
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_crypt_ecb(&ctx->aes_ctx, MBEDTLS_AES_ENCRYPT,
ctx->counter, p)) != 0) {
goto exit;
}
#else
status = psa_cipher_update(&ctx->psa_ctx.operation, ctx->counter, sizeof(ctx->counter),
p, MBEDTLS_CTR_DRBG_BLOCKSIZE, &tmp_len);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
p += MBEDTLS_CTR_DRBG_BLOCKSIZE;
}
@ -267,10 +379,20 @@ static int ctr_drbg_update_internal(mbedtls_ctr_drbg_context *ctx,
/*
* Update key and counter
*/
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_setkey_enc(&ctx->aes_ctx, tmp,
MBEDTLS_CTR_DRBG_KEYBITS)) != 0) {
goto exit;
}
#else
ctr_drbg_destroy_psa_contex(&ctx->psa_ctx);
status = ctr_drbg_setup_psa_context(&ctx->psa_ctx, tmp, MBEDTLS_CTR_DRBG_KEYSIZE);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
memcpy(ctx->counter, tmp + MBEDTLS_CTR_DRBG_KEYSIZE,
MBEDTLS_CTR_DRBG_BLOCKSIZE);
@ -447,10 +569,20 @@ int mbedtls_ctr_drbg_seed(mbedtls_ctr_drbg_context *ctx,
good_nonce_len(ctx->entropy_len));
/* Initialize with an empty key. */
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_setkey_enc(&ctx->aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS)) != 0) {
return ret;
}
#else
psa_status_t status;
status = ctr_drbg_setup_psa_context(&ctx->psa_ctx, key, MBEDTLS_CTR_DRBG_KEYSIZE);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
return status;
}
#endif
/* Do the initial seeding. */
if ((ret = mbedtls_ctr_drbg_reseed_internal(ctx, custom, len,
@ -531,10 +663,22 @@ int mbedtls_ctr_drbg_random_with_add(void *p_rng,
/*
* Crypt counter block
*/
#if defined(MBEDTLS_AES_C)
if ((ret = mbedtls_aes_crypt_ecb(&ctx->aes_ctx, MBEDTLS_AES_ENCRYPT,
ctx->counter, tmp)) != 0) {
goto exit;
}
#else
psa_status_t status;
size_t tmp_len;
status = psa_cipher_update(&ctx->psa_ctx.operation, ctx->counter, sizeof(ctx->counter),
tmp, MBEDTLS_CTR_DRBG_BLOCKSIZE, &tmp_len);
if (status != PSA_SUCCESS) {
ret = psa_generic_status_to_mbedtls(status);
goto exit;
}
#endif
use_len = (output_len > MBEDTLS_CTR_DRBG_BLOCKSIZE)
? MBEDTLS_CTR_DRBG_BLOCKSIZE : output_len;