tee/TlcKeymint/src/AndroidSharedSecret.cpp

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#define LOG_TAG "android.hardware.security.sharedsecret-impl"
#include <log/log.h>

#include "AndroidSharedSecret.h"
#include <aidl/android/hardware/security/keymint/ErrorCode.h>

namespace aidl::android::hardware::security::sharedsecret {

inline ScopedAStatus kmError2ScopedAStatus(const keymaster_error_t value) {
    return (value == KM_ERROR_OK
                ? ScopedAStatus::ok()
                : ScopedAStatus(AStatus_fromServiceSpecificError(static_cast<int32_t>(value))));
}

class KmSharedSecretParameters : public keymaster_hmac_sharing_parameters_set_t {
public:
    KmSharedSecretParameters(const vector<SharedSecretParameters>& sharedSecretParams) {
        params = new keymaster_hmac_sharing_parameters_t[sharedSecretParams.size()];
        length = sharedSecretParams.size();
        for (size_t i = 0; i < sharedSecretParams.size(); ++i) {
            params[i].seed.data = sharedSecretParams[i].seed.data();
            params[i].seed.data_length = sharedSecretParams[i].seed.size();
            memcpy(params[i].nonce, sharedSecretParams[i].nonce.data(), 32); // FIXME make more robust
        }
    }
    KmSharedSecretParameters(const KmSharedSecretParameters&) = delete;
    ~KmSharedSecretParameters() {
        delete[] params;
    }
};

AndroidSharedSecret::AndroidSharedSecret(std::shared_ptr<keymint::AndroidKeyMintDevice> keymint)
    : impl_(keymint->getImpl()) {}

AndroidSharedSecret::~AndroidSharedSecret() {}

ScopedAStatus AndroidSharedSecret::getSharedSecretParameters(SharedSecretParameters* params) {
    keymaster_hmac_sharing_parameters_t _params = {};
    keymaster_error_t ret = impl_->get_hmac_sharing_parameters(
        &_params);
    if (ret != KM_ERROR_OK) {
        return kmError2ScopedAStatus(ret);
    }
    params->seed = vector<uint8_t>(_params.seed.data, _params.seed.data + _params.seed.data_length);
    params->nonce = vector<uint8_t>(_params.nonce, _params.nonce+sizeof(_params.nonce));
    return ScopedAStatus::ok();
}

ScopedAStatus AndroidSharedSecret::computeSharedSecret(const vector<SharedSecretParameters>& params,
                                                       vector<uint8_t>* sharingCheck) {
    const KmSharedSecretParameters _params(params);
    keymaster_blob_t _sharing_check = {};
    keymaster_error_t ret = impl_->compute_shared_hmac(
        &_params, &_sharing_check);
    if (ret != KM_ERROR_OK) {
        return kmError2ScopedAStatus(ret);
    }
    *sharingCheck = vector<uint8_t>(_sharing_check.data, _sharing_check.data + _sharing_check.data_length);
    return ScopedAStatus::ok();
}

}  // namespace aidl::android::hardware::security::sharedsecret