Non-anonymous Key Attestation (for System Applications Only) (C/C++)
Non-anonymous key attestation is available only for system applications, and the caller must have the ohos.permission.ATTEST_KEY permission.
How to Develop
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Set the key alias (keyAlias), which cannot exceed 64 bytes.
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Initialize the parameter set. Use OH_Huks_InitParamSet, OH_Huks_AddParams, and OH_Huks_BuildParamSet to construct paramSet. paramSet must contain OH_Huks_KeyAlg, OH_Huks_KeySize, and OH_Huks_KeyPurpose.
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Use OH_Huks_AttestKeyItem with the key alias and parameter set to perform key attestation.
#include "huks/native_huks_api.h"
#include "huks/native_huks_param.h"
#include <string.h>
OH_Huks_Result InitParamSet(
struct OH_Huks_ParamSet **paramSet,
const struct OH_Huks_Param *params,
uint32_t paramCount)
{
OH_Huks_Result ret = OH_Huks_InitParamSet(paramSet);
if (ret.errorCode != OH_HUKS_SUCCESS) {
return ret;
}
ret = OH_Huks_AddParams(*paramSet, params, paramCount);
if (ret.errorCode != OH_HUKS_SUCCESS) {
OH_Huks_FreeParamSet(paramSet);
return ret;
}
ret = OH_Huks_BuildParamSet(paramSet);
if (ret.errorCode != OH_HUKS_SUCCESS) {
OH_Huks_FreeParamSet(paramSet);
return ret;
}
return ret;
}
static uint32_t g_size = 4096;
static uint32_t CERT_COUNT = 4;
void FreeCertChain(struct OH_Huks_CertChain **certChain, const uint32_t pos)
{
if (certChain == nullptr || *certChain == nullptr) {
return;
}
if ((*certChain)->certs == nullptr) {
free(*certChain);
*certChain = nullptr;
return;
}
for (uint32_t j = 0; j < pos; j++) {
if ((*certChain)->certs[j].data != nullptr) {
free((*certChain)->certs[j].data);
(*certChain)->certs[j].data = nullptr;
}
}
if ((*certChain)->certs != nullptr) {
free((*certChain)->certs);
(*certChain)->certs = nullptr;
}
if (*certChain != nullptr) {
free(*certChain);
*certChain = nullptr;
}
}
int32_t ConstructDataToCertChain(struct OH_Huks_CertChain **certChain)
{
*certChain = (struct OH_Huks_CertChain *)malloc(sizeof(struct OH_Huks_CertChain));
if (*certChain == nullptr) {
return OH_HUKS_ERR_CODE_ILLEGAL_ARGUMENT;
}
(*certChain)->certsCount = CERT_COUNT;
(*certChain)->certs = (struct OH_Huks_Blob *)malloc(sizeof(struct OH_Huks_Blob) * ((*certChain)->certsCount));
if ((*certChain)->certs == nullptr) {
free(*certChain);
*certChain = nullptr;
}
for (uint32_t i = 0; i < (*certChain)->certsCount; i++) {
(*certChain)->certs[i].size = g_size;
(*certChain)->certs[i].data = (uint8_t *)malloc((*certChain)->certs[i].size);
if ((*certChain)->certs[i].data == nullptr) {
FreeCertChain(certChain, i);
return OH_HUKS_ERR_CODE_ILLEGAL_ARGUMENT;
}
}
return 0;
}
static struct OH_Huks_Param g_genAttestParams[] = {
{ .tag = OH_HUKS_TAG_ALGORITHM, .uint32Param = OH_HUKS_ALG_RSA },
{ .tag = OH_HUKS_TAG_KEY_SIZE, .uint32Param = OH_HUKS_RSA_KEY_SIZE_2048 },
{ .tag = OH_HUKS_TAG_PURPOSE, .uint32Param = OH_HUKS_KEY_PURPOSE_VERIFY },
{ .tag = OH_HUKS_TAG_DIGEST, .uint32Param = OH_HUKS_DIGEST_SHA256 },
{ .tag = OH_HUKS_TAG_PADDING, .uint32Param = OH_HUKS_PADDING_PSS },
{ .tag = OH_HUKS_TAG_BLOCK_MODE, .uint32Param = OH_HUKS_MODE_ECB },
};
#define CHALLENGE_DATA "hi_challenge_data"
static struct OH_Huks_Blob g_challenge = { sizeof(CHALLENGE_DATA), (uint8_t *)CHALLENGE_DATA };
static napi_value AttestKey(napi_env env, napi_callback_info info)
{
/* 1. Set the key alias. */
struct OH_Huks_Blob genAlias = {
(uint32_t)strlen("test_attest"),
(uint8_t *)"test_attest"
};
static struct OH_Huks_Param g_attestParams[] = {
{ .tag = OH_HUKS_TAG_ATTESTATION_CHALLENGE, .blob = g_challenge },
{ .tag = OH_HUKS_TAG_ATTESTATION_ID_ALIAS, .blob = genAlias },
};
struct OH_Huks_ParamSet *genParamSet = nullptr;
struct OH_Huks_ParamSet *attestParamSet = nullptr;
OH_Huks_Result ohResult;
OH_Huks_CertChain *certChain = NULL;
do {
/* 2. Initialize the key parameter set. */
ohResult = InitParamSet(&genParamSet, g_genAttestParams, sizeof(g_genAttestParams) / sizeof(OH_Huks_Param));
if (ohResult.errorCode != OH_HUKS_SUCCESS) {
break;
}
ohResult = InitParamSet(&attestParamSet, g_attestParams, sizeof(g_attestParams) / sizeof(OH_Huks_Param));
if (ohResult.errorCode != OH_HUKS_SUCCESS) {
break;
}
ohResult = OH_Huks_GenerateKeyItem(&genAlias, genParamSet, nullptr);
if (ohResult.errorCode != OH_HUKS_SUCCESS) {
break;
}
(void)ConstructDataToCertChain(&certChain);
/* 3. Attest the key. */
ohResult = OH_Huks_AttestKeyItem(&genAlias, attestParamSet, certChain);
} while (0);
if (certChain != nullptr) {
FreeCertChain(&certChain, certChain->certsCount);
}
OH_Huks_FreeParamSet(&genParamSet);
OH_Huks_FreeParamSet(&attestParamSet);
(void)OH_Huks_DeleteKeyItem(&genAlias, NULL);
napi_value ret;
napi_create_int32(env, ohResult.errorCode, &ret);
return ret;
}