83 lines
1.8 KiB
C
83 lines
1.8 KiB
C
/*
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* Copyright (C) 2024 BayLibre SAS
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <string.h>
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#include <zephyr/types.h>
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#include <errno.h>
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#include <zephyr/data/jwt.h>
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#include <zephyr/data/json.h>
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#include <zephyr/random/random.h>
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#include <tinycrypt/ctr_prng.h>
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#include <tinycrypt/sha256.h>
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#include <tinycrypt/ecc_dsa.h>
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#include <tinycrypt/constants.h>
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#include "jwt.h"
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static TCCtrPrng_t prng_state;
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static bool prng_init;
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static const char personalize[] = "zephyr:drivers/jwt/jwt.c";
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static int setup_prng(void)
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{
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if (prng_init) {
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return 0;
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}
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prng_init = true;
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uint8_t entropy[TC_AES_KEY_SIZE + TC_AES_BLOCK_SIZE];
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sys_rand_get(entropy, sizeof(entropy));
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int res = tc_ctr_prng_init(&prng_state, (const uint8_t *)&entropy, sizeof(entropy),
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personalize, sizeof(personalize));
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return res == TC_CRYPTO_SUCCESS ? 0 : -EINVAL;
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}
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/* This function is declared in
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* modules/crypto/tinycrypt/lib/include/tinycrypt/ecc_platform_specific.h.
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*
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* TinyCrypt expects this function to be implemented somewhere when using the
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* ECC module.
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*/
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int default_CSPRNG(uint8_t *dest, unsigned int size)
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{
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int res = tc_ctr_prng_generate(&prng_state, NULL, 0, dest, size);
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return res;
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}
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int jwt_sign_impl(struct jwt_builder *builder, const unsigned char *der_key, size_t der_key_len,
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unsigned char *sig, size_t sig_size)
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{
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struct tc_sha256_state_struct ctx;
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uint8_t hash[32];
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int res;
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ARG_UNUSED(sig_size);
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tc_sha256_init(&ctx);
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tc_sha256_update(&ctx, builder->base, builder->buf - builder->base);
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tc_sha256_final(hash, &ctx);
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res = setup_prng();
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if (res != 0) {
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return res;
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}
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/* Note that tinycrypt only supports P-256. */
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res = uECC_sign(der_key, hash, sizeof(hash), sig, &curve_secp256r1);
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if (res != TC_CRYPTO_SUCCESS) {
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return -EINVAL;
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}
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return 0;
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}
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