348 lines
9.1 KiB
C
348 lines
9.1 KiB
C
#include "crypto.h"
|
|
#include "system.h"
|
|
#include "constants.h"
|
|
#include "storage.h"
|
|
#include "dev_name.h"
|
|
|
|
#include <string.h>
|
|
#include <mbedtls/build_info.h>
|
|
#include <mbedtls/platform.h>
|
|
#include <mbedtls/entropy.h>
|
|
#include <mbedtls/ctr_drbg.h>
|
|
#include <mbedtls/ecdsa.h>
|
|
#include <mbedtls/sha256.h>
|
|
#include <mbedtls/pk.h>
|
|
#include <mbedtls/x509_csr.h>
|
|
#include <mbedtls/base64.h>
|
|
#include "esp_log.h"
|
|
|
|
#define ECPARAMS MBEDTLS_ECP_DP_SECP256R1
|
|
|
|
static const char *TAG = "crypto";
|
|
|
|
static const char *pers = "ecdsa";
|
|
|
|
static void seed_ctr_drbg_context(mbedtls_entropy_context *entropy, mbedtls_ctr_drbg_context *ctr_drbg)
|
|
{
|
|
int ret;
|
|
|
|
mbedtls_entropy_init(entropy);
|
|
mbedtls_ctr_drbg_init(ctr_drbg);
|
|
|
|
ESP_LOGI(TAG, "Seed Mbedtls\n");
|
|
if ((ret = mbedtls_ctr_drbg_seed(ctr_drbg, mbedtls_entropy_func, entropy,
|
|
(const unsigned char *)pers,
|
|
strlen(pers))) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_ctr_drbg_seed returned %d\n", ret);
|
|
reboot();
|
|
}
|
|
}
|
|
|
|
bool crypto_gen_priv_key()
|
|
{
|
|
// Check if a private key has already been defined for this device
|
|
if (storage_get_priv_key(NULL) > 0)
|
|
return false;
|
|
|
|
int ret = 1;
|
|
|
|
mbedtls_pk_context key;
|
|
mbedtls_pk_init(&key);
|
|
|
|
mbedtls_entropy_context entropy;
|
|
mbedtls_ctr_drbg_context ctr_drbg;
|
|
seed_ctr_drbg_context(&entropy, &ctr_drbg);
|
|
|
|
ESP_LOGI(TAG, "PK info from type\n");
|
|
if ((ret = mbedtls_pk_setup(&key, mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY))) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_pk_setup returned -0x%04x", (unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
|
|
// Generate private key
|
|
ESP_LOGI(TAG, "Generate private key\n");
|
|
ret = mbedtls_ecp_gen_key(ECPARAMS,
|
|
mbedtls_pk_ec(key),
|
|
mbedtls_ctr_drbg_random, &ctr_drbg);
|
|
if (ret != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_ecp_gen_key returned -0x%04x",
|
|
(unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
|
|
// Export private key
|
|
ESP_LOGI(TAG, "Export private key\n");
|
|
unsigned char *key_buff = malloc(PRV_KEY_DER_MAX_BYTES);
|
|
if ((ret = mbedtls_pk_write_key_der(&key, key_buff, PRV_KEY_DER_MAX_BYTES)) < 1)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_pk_write_key_der returned -0x%04x",
|
|
(unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
|
|
storage_set_priv_key(key_buff + PRV_KEY_DER_MAX_BYTES - ret, ret);
|
|
free(key_buff);
|
|
|
|
mbedtls_pk_free(&key);
|
|
mbedtls_ctr_drbg_free(&ctr_drbg);
|
|
mbedtls_entropy_free(&entropy);
|
|
|
|
return true;
|
|
}
|
|
|
|
void crypto_print_priv_key()
|
|
{
|
|
int ret;
|
|
|
|
unsigned char *key_buff = malloc(PRV_KEY_DER_MAX_BYTES);
|
|
size_t key_len = storage_get_priv_key(key_buff);
|
|
assert(key_len > 0);
|
|
|
|
mbedtls_pk_context key;
|
|
mbedtls_pk_init(&key);
|
|
|
|
mbedtls_entropy_context entropy;
|
|
mbedtls_ctr_drbg_context ctr_drbg;
|
|
seed_ctr_drbg_context(&entropy, &ctr_drbg);
|
|
|
|
ESP_LOGI(TAG, "Parse private key (len = %d)\n", key_len);
|
|
if ((ret = mbedtls_pk_parse_key(&key, key_buff, key_len, NULL, 0, mbedtls_ctr_drbg_random, &ctr_drbg)) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_pk_parse_key returned -0x%04x",
|
|
(unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
free(key_buff);
|
|
|
|
ESP_LOGI(TAG, "Show private key\n");
|
|
unsigned char *out = malloc(16000);
|
|
memset(out, 0, 16000);
|
|
if ((ret = mbedtls_pk_write_key_pem(&key, out, 16000)) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_pk_write_key_pem returned -0x%04x",
|
|
(unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
|
|
ESP_LOGI(TAG, "%s", out);
|
|
free(out);
|
|
|
|
mbedtls_pk_free(&key);
|
|
mbedtls_ctr_drbg_free(&ctr_drbg);
|
|
mbedtls_entropy_free(&entropy);
|
|
}
|
|
|
|
/**
|
|
* Get secret point value of our private key
|
|
*/
|
|
static bool crypto_get_priv_key_mpi(mbedtls_mpi *dst)
|
|
{
|
|
int ret;
|
|
|
|
unsigned char *key_buff = malloc(PRV_KEY_DER_MAX_BYTES);
|
|
size_t key_len = storage_get_priv_key(key_buff);
|
|
assert(key_len > 0);
|
|
|
|
mbedtls_pk_context key;
|
|
mbedtls_pk_init(&key);
|
|
|
|
mbedtls_entropy_context entropy;
|
|
mbedtls_ctr_drbg_context ctr_drbg;
|
|
seed_ctr_drbg_context(&entropy, &ctr_drbg);
|
|
|
|
ESP_LOGI(TAG, "Parse private key (len = %d)\n", key_len);
|
|
if ((ret = mbedtls_pk_parse_key(&key, key_buff, key_len, NULL, 0, mbedtls_ctr_drbg_random, &ctr_drbg)) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_pk_parse_key returned -0x%04x",
|
|
(unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
free(key_buff);
|
|
|
|
ESP_LOGI(TAG, "Extract private key");
|
|
mbedtls_ecp_keypair *kp = mbedtls_pk_ec(key);
|
|
|
|
mbedtls_mpi_init(dst);
|
|
mbedtls_mpi_copy(dst, &kp->private_d);
|
|
|
|
mbedtls_pk_free(&key);
|
|
mbedtls_ctr_drbg_free(&ctr_drbg);
|
|
mbedtls_entropy_free(&entropy);
|
|
|
|
return true;
|
|
}
|
|
|
|
char *crypto_get_csr()
|
|
{
|
|
int ret;
|
|
|
|
unsigned char *key_buff = malloc(PRV_KEY_DER_MAX_BYTES);
|
|
size_t key_len = storage_get_priv_key(key_buff);
|
|
assert(key_len > 0);
|
|
|
|
mbedtls_pk_context key;
|
|
mbedtls_pk_init(&key);
|
|
|
|
mbedtls_entropy_context entropy;
|
|
mbedtls_ctr_drbg_context ctr_drbg;
|
|
seed_ctr_drbg_context(&entropy, &ctr_drbg);
|
|
|
|
ESP_LOGI(TAG, "Parse private key (len = %d)\n", key_len);
|
|
if ((ret = mbedtls_pk_parse_key(&key, key_buff, key_len, NULL, 0, mbedtls_ctr_drbg_random, &ctr_drbg)) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_pk_parse_key returned -0x%04x",
|
|
(unsigned int)-ret);
|
|
reboot();
|
|
}
|
|
free(key_buff);
|
|
|
|
// Create CSR
|
|
mbedtls_x509write_csr req;
|
|
mbedtls_x509write_csr_init(&req);
|
|
mbedtls_x509write_csr_set_md_alg(&req, MBEDTLS_MD_SHA256);
|
|
|
|
char subj[DEV_NAME_LEN + 4];
|
|
char *n = dev_name();
|
|
sprintf(subj, "CN=%s", n);
|
|
free(n);
|
|
if ((ret = mbedtls_x509write_csr_set_subject_name(&req, subj)) != 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_x509write_csr_set_subject_name returned %d", ret);
|
|
reboot();
|
|
}
|
|
|
|
ESP_LOGI(TAG, "Sign CSR with private key\n");
|
|
mbedtls_x509write_csr_set_key(&req, &key);
|
|
|
|
char *csr = malloc(4096);
|
|
if ((ret = mbedtls_x509write_csr_pem(&req, (u_char *)csr, 4096, mbedtls_ctr_drbg_random, &ctr_drbg)) < 0)
|
|
{
|
|
ESP_LOGE(TAG, " failed\n ! mbedtls_x509write_csr_pem returned %d", ret);
|
|
reboot();
|
|
}
|
|
|
|
mbedtls_x509write_csr_free(&req);
|
|
mbedtls_pk_free(&key);
|
|
mbedtls_ctr_drbg_free(&ctr_drbg);
|
|
mbedtls_entropy_free(&entropy);
|
|
|
|
return csr;
|
|
}
|
|
|
|
char *crypto_encode_base64_safe_url(const char *src, size_t srclen)
|
|
{
|
|
size_t olen = 0;
|
|
mbedtls_base64_encode(NULL, 0, &olen, (unsigned char *)src, srclen);
|
|
|
|
if (olen < 1)
|
|
{
|
|
ESP_LOGE(TAG, "Failed to determine base64 buffer size!");
|
|
return NULL;
|
|
}
|
|
|
|
char *out = calloc(1, olen);
|
|
if (!out)
|
|
{
|
|
ESP_LOGE(TAG, "Failed to allocate memory for destination buffer!");
|
|
return NULL;
|
|
}
|
|
|
|
if (mbedtls_base64_encode((unsigned char *)out, olen, &olen, (unsigned char *)src, srclen) != 0)
|
|
{
|
|
ESP_LOGE(TAG, "Failed to perfom base64 encoding!");
|
|
free(out);
|
|
return NULL;
|
|
}
|
|
|
|
// Convert base64 encoding to base64URL
|
|
for (size_t i = 0; i < olen; i++)
|
|
{
|
|
switch (out[i])
|
|
{
|
|
case '+':
|
|
out[i] = '-';
|
|
break;
|
|
case '/':
|
|
out[i] = '_';
|
|
break;
|
|
case '=':
|
|
out[i] = '\0';
|
|
break;
|
|
}
|
|
}
|
|
|
|
return out;
|
|
}
|
|
|
|
#define HASH_LEN 32
|
|
|
|
char *crypto_sign_sha256_payload(const char *src, const size_t src_len, size_t *dstlen)
|
|
{
|
|
int ret;
|
|
uint8_t r_be[32] = {0};
|
|
uint8_t s_be[32] = {0};
|
|
|
|
// Load private key
|
|
mbedtls_mpi key_mpi;
|
|
if (!crypto_get_priv_key_mpi(&key_mpi))
|
|
{
|
|
ESP_LOGE(TAG, "Failed to load private key MPI!");
|
|
return NULL;
|
|
}
|
|
|
|
mbedtls_entropy_context entropy;
|
|
mbedtls_ctr_drbg_context ctr_drbg;
|
|
seed_ctr_drbg_context(&entropy, &ctr_drbg);
|
|
|
|
mbedtls_mpi r, s;
|
|
mbedtls_mpi_init(&r);
|
|
mbedtls_mpi_init(&s);
|
|
|
|
mbedtls_ecdsa_context ecdsa_context;
|
|
mbedtls_ecdsa_init(&ecdsa_context);
|
|
|
|
mbedtls_ecp_group_load(&ecdsa_context.MBEDTLS_PRIVATE(grp), MBEDTLS_ECP_DP_SECP256R1);
|
|
|
|
// Compute sha256
|
|
uint8_t sha256_out[HASH_LEN] = {0};
|
|
mbedtls_sha256((unsigned char *)src, src_len, sha256_out, 0);
|
|
|
|
// Compute signature
|
|
ret = mbedtls_ecdsa_sign(&ecdsa_context.MBEDTLS_PRIVATE(grp), &r, &s, &key_mpi, sha256_out, HASH_LEN, mbedtls_ctr_drbg_random, &ctr_drbg);
|
|
|
|
// Extract R & S (as per RFC 7518)
|
|
mbedtls_mpi_write_binary(&r, r_be, 32);
|
|
mbedtls_mpi_write_binary(&s, s_be, 32);
|
|
|
|
mbedtls_ctr_drbg_free(&ctr_drbg);
|
|
mbedtls_entropy_free(&entropy);
|
|
|
|
mbedtls_mpi_free(&r);
|
|
mbedtls_mpi_free(&s);
|
|
mbedtls_mpi_free(&key_mpi);
|
|
|
|
mbedtls_ecdsa_free(&ecdsa_context);
|
|
|
|
if (ret != 0)
|
|
{
|
|
ESP_LOGE(TAG, "Failed to perfom base64 encoding!");
|
|
return NULL;
|
|
}
|
|
|
|
// Prepare output
|
|
char *out = calloc(1, 64);
|
|
if (!out)
|
|
{
|
|
ESP_LOGE(TAG, "Failed to allocate memory to store signature!");
|
|
return NULL;
|
|
}
|
|
|
|
memcpy(out, &r_be, 32);
|
|
memcpy(out + 32, &s_be, 32);
|
|
|
|
*dstlen = 64;
|
|
return out;
|
|
} |