components/service/crypto/client/cpp/crypto_client.cpp

/*
 * Copyright (c) 2020, Arm Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <cstring>
#include <cstdlib>
#include "crypto_client.h"
#include <protocols/rpc/common/packed-c/status.h>
#include <service/common/serializer/protobuf/pb_helper.h>
#include <rpc_caller.h>
#include <service/crypto/protobuf/opcodes.pb.h>
#include <service/crypto/protobuf/generate_key.pb.h>
#include <service/crypto/protobuf/destroy_key.pb.h>
#include <service/crypto/protobuf/import_key.pb.h>
#include <service/crypto/protobuf/open_key.pb.h>
#include <service/crypto/protobuf/close_key.pb.h>
#include <service/crypto/protobuf/export_key.pb.h>
#include <service/crypto/protobuf/export_public_key.pb.h>
#include <service/crypto/protobuf/sign_hash.pb.h>
#include <service/crypto/protobuf/verify_hash.pb.h>
#include <service/crypto/protobuf/asymmetric_encrypt.pb.h>
#include <service/crypto/protobuf/asymmetric_decrypt.pb.h>
#include <service/crypto/protobuf/generate_random.pb.h>
#include <pb_encode.h>
#include <pb_decode.h>

crypto_client::crypto_client() :
    m_caller(NULL),
    m_err_rpc_status(TS_RPC_CALL_ACCEPTED)
{

}

crypto_client::crypto_client(struct rpc_caller *caller) :
    m_caller(caller),
    m_err_rpc_status(TS_RPC_CALL_ACCEPTED)
{

}

crypto_client::~crypto_client()
{

}

int crypto_client::err_rpc_status() const
{
    return m_err_rpc_status;
}

psa_status_t crypto_client::generate_key(const psa_key_attributes_t *attributes, psa_key_handle_t *handle)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_GenerateKeyIn req_msg = ts_crypto_GenerateKeyIn_init_default;

    translate_key_attributes(req_msg.attributes, *attributes);
    req_msg.has_attributes = true;

    if (pb_get_encoded_size(&req_len, ts_crypto_GenerateKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_GenerateKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                ts_crypto_Opcode_GENERATE_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    ts_crypto_GenerateKeyOut resp_msg = ts_crypto_GenerateKeyOut_init_default;
                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_GenerateKeyOut_fields, &resp_msg)) {

                        *handle = resp_msg.handle;
                    }
                    else {
                        /* Failed to decode response message */
                        psa_status = PSA_ERROR_GENERIC_ERROR;
                    }
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

psa_status_t crypto_client::destroy_key(psa_key_handle_t handle)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_DestroyKeyIn req_msg = ts_crypto_DestroyKeyIn_init_default;

    req_msg.handle = handle;

    if (pb_get_encoded_size(&req_len, ts_crypto_DestroyKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_DestroyKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                ts_crypto_Opcode_DESTROY_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) psa_status = opstatus;

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

psa_status_t crypto_client::open_key(psa_key_id_t id, psa_key_handle_t *handle)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_OpenKeyIn req_msg = ts_crypto_OpenKeyIn_init_default;
    req_msg.id = id;

	if (pb_get_encoded_size(&req_len, ts_crypto_OpenKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_OpenKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                        ts_crypto_Opcode_OPEN_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    ts_crypto_OpenKeyOut resp_msg = ts_crypto_OpenKeyOut_init_default;
                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_OpenKeyOut_fields, &resp_msg)) {

                        *handle = resp_msg.handle;
                    }
                    else {
                        /* Failed to decode response message */
                        psa_status = PSA_ERROR_GENERIC_ERROR;
                    }
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

psa_status_t crypto_client::close_key(psa_key_handle_t handle)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_CloseKeyIn req_msg = ts_crypto_CloseKeyIn_init_default;

    req_msg.handle = handle;

    if (pb_get_encoded_size(&req_len, ts_crypto_CloseKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_CloseKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                ts_crypto_Opcode_CLOSE_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) psa_status = opstatus;

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

psa_status_t crypto_client::import_key(const psa_key_attributes_t *attributes,
                        const uint8_t *data, size_t data_length, psa_key_handle_t *handle)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_ImportKeyIn req_msg = ts_crypto_ImportKeyIn_init_default;
    pb_bytes_array_t *key_byte_array = pb_malloc_byte_array_containing_bytes(data, data_length);

    translate_key_attributes(req_msg.attributes, *attributes);
    req_msg.has_attributes = true;
    req_msg.data = pb_out_byte_array(key_byte_array);

    if (pb_get_encoded_size(&req_len, ts_crypto_ImportKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_ImportKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                ts_crypto_Opcode_IMPORT_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    ts_crypto_ImportKeyOut resp_msg = ts_crypto_ImportKeyOut_init_default;
                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_ImportKeyOut_fields, &resp_msg)) {

                        *handle = resp_msg.handle;
                    }
                    else {
                        /* Failed to decode response message */
                        psa_status = PSA_ERROR_GENERIC_ERROR;
                    }
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    ::free(key_byte_array);

    return psa_status;
}

psa_status_t crypto_client::export_key(psa_key_handle_t handle,
                        uint8_t *data, size_t data_size,
                        size_t *data_length)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_ExportKeyIn req_msg = ts_crypto_ExportKeyIn_init_default;
    req_msg.handle = handle;

    *data_length = 0; /* For failure case */

	if (pb_get_encoded_size(&req_len, ts_crypto_ExportKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_ExportKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                ts_crypto_Opcode_EXPORT_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    ts_crypto_ExportKeyOut resp_msg = ts_crypto_ExportKeyOut_init_default;
                    pb_bytes_array_t *exported_key = pb_malloc_byte_array(resp_len);

                    if (exported_key) {

                        resp_msg.data = pb_in_byte_array(exported_key);
                        pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                        if (pb_decode(&istream, ts_crypto_ExportKeyOut_fields, &resp_msg)) {

                            if (exported_key->size <= data_size) {

                                memcpy(data, exported_key->bytes, exported_key->size);
                                *data_length = exported_key->size;
                            }
                            else {
                                /* Provided buffer is too small */
                                psa_status = PSA_ERROR_BUFFER_TOO_SMALL;
                            }
                        }
                        else {
                            /* Failed to decode response message */
                            psa_status = PSA_ERROR_GENERIC_ERROR;
                        }

                        ::free(exported_key);
                    }
                    else {
                        /* Failed to allocate buffer for exported key */
                        psa_status = PSA_ERROR_INSUFFICIENT_MEMORY;
                    }
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

psa_status_t crypto_client::export_public_key(psa_key_handle_t handle,
                                uint8_t *data, size_t data_size, size_t *data_length)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_ExportPublicKeyIn req_msg = ts_crypto_ExportPublicKeyIn_init_default;
    req_msg.handle = handle;

    *data_length = 0; /* For failure case */

	if (pb_get_encoded_size(&req_len, ts_crypto_ExportPublicKeyIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_ExportPublicKeyIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                ts_crypto_Opcode_EXPORT_PUBLIC_KEY, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    ts_crypto_ExportPublicKeyOut resp_msg = ts_crypto_ExportPublicKeyOut_init_default;
                    pb_bytes_array_t *exported_key = pb_malloc_byte_array(resp_len);

                    if (exported_key) {

                        resp_msg.data = pb_in_byte_array(exported_key);
                        pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                        if (pb_decode(&istream, ts_crypto_ExportPublicKeyOut_fields, &resp_msg)) {

                            if (exported_key->size <= data_size) {

                                memcpy(data, exported_key->bytes, exported_key->size);
                                *data_length = exported_key->size;
                            }
                            else {
                                /* Provided buffer is too small */
                                psa_status = PSA_ERROR_BUFFER_TOO_SMALL;
                            }
                        }
                        else {
                            /* Failed to decode response message */
                            psa_status = PSA_ERROR_GENERIC_ERROR;
                        }

                        ::free(exported_key);
                    }
                    else {
                        /* Failed to alloocate buffer for exported key */
                        psa_status = PSA_ERROR_INSUFFICIENT_MEMORY;
                    }
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

psa_status_t crypto_client::sign_hash(psa_key_handle_t handle, psa_algorithm_t alg,
                            const uint8_t *hash, size_t hash_length,
                            uint8_t *signature, size_t signature_size, size_t *signature_length)
{
    size_t req_len;
    pb_bytes_array_t *hash_byte_array = pb_malloc_byte_array_containing_bytes(hash, hash_length);
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_SignHashIn req_msg = ts_crypto_SignHashIn_init_default;

    *signature_length = 0;  /* For failure case */

    req_msg.handle = handle;
    req_msg.alg = alg;
	req_msg.hash = pb_out_byte_array(hash_byte_array);

	if (pb_get_encoded_size(&req_len, ts_crypto_SignHashIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_SignHashIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                        ts_crypto_Opcode_SIGN_HASH, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    pb_bytes_array_t *sig_byte_array = pb_malloc_byte_array(PSA_SIGNATURE_MAX_SIZE);
                    ts_crypto_SignHashOut resp_msg = ts_crypto_SignHashOut_init_default;
                    resp_msg.signature = pb_in_byte_array(sig_byte_array);

                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_SignHashOut_fields, &resp_msg)) {

                        if (sig_byte_array->size <= signature_size) {

                            memcpy(signature, sig_byte_array->bytes, sig_byte_array->size);
                            *signature_length = sig_byte_array->size;
                        }
                        else {
                            /* Provided buffer is too small */
                            psa_status = PSA_ERROR_BUFFER_TOO_SMALL;
                        }
                    }
                    else {
                        /* Failed to decode response message */
                        psa_status = PSA_ERROR_GENERIC_ERROR;
                    }

                    ::free(sig_byte_array);
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    ::free(hash_byte_array);

    return psa_status;
}


psa_status_t crypto_client::verify_hash(psa_key_handle_t handle, psa_algorithm_t alg,
                        const uint8_t *hash, size_t hash_length,
                        const uint8_t *signature, size_t signature_length)
{
    size_t req_len;
    pb_bytes_array_t *hash_byte_array = pb_malloc_byte_array_containing_bytes(hash, hash_length);
    pb_bytes_array_t *sig_byte_array = pb_malloc_byte_array_containing_bytes(signature, signature_length);
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_VerifyHashIn req_msg = ts_crypto_VerifyHashIn_init_default;

    req_msg.handle = handle;
    req_msg.alg = alg;
	req_msg.hash = pb_out_byte_array(hash_byte_array);
    req_msg.signature = pb_out_byte_array(sig_byte_array);

	if (pb_get_encoded_size(&req_len, ts_crypto_VerifyHashIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_VerifyHashIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                        ts_crypto_Opcode_VERIFY_HASH, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) psa_status = opstatus;

            rpc_caller_end(m_caller, call_handle);
        }
    }

    ::free(hash_byte_array);
    ::free(sig_byte_array);

    return psa_status;
}

psa_status_t crypto_client::asymmetric_encrypt(psa_key_handle_t handle, psa_algorithm_t alg,
                        const uint8_t *input, size_t input_length,
                        const uint8_t *salt, size_t salt_length,
                        uint8_t *output, size_t output_size, size_t *output_length)
{
    size_t req_len;
    pb_bytes_array_t *plaintext_byte_array = pb_malloc_byte_array_containing_bytes(input, input_length);
    pb_bytes_array_t *salt_byte_array = pb_malloc_byte_array_containing_bytes(salt, salt_length);
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_AsymmetricEncryptIn req_msg = ts_crypto_AsymmetricEncryptIn_init_default;

    *output_length = 0;  /* For failure case */

    req_msg.handle = handle;
    req_msg.alg = alg;
	req_msg.plaintext = pb_out_byte_array(plaintext_byte_array);
    req_msg.salt = pb_out_byte_array(salt_byte_array);

	if (pb_get_encoded_size(&req_len, ts_crypto_AsymmetricEncryptIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus = PSA_ERROR_GENERIC_ERROR;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_AsymmetricEncryptIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                        ts_crypto_Opcode_ASYMMETRIC_ENCRYPT, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    pb_bytes_array_t *ciphertext_byte_array = pb_malloc_byte_array(output_size);
                    ts_crypto_AsymmetricEncryptOut resp_msg = ts_crypto_AsymmetricEncryptOut_init_default;
                    resp_msg.ciphertext = pb_in_byte_array(ciphertext_byte_array);

                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_AsymmetricEncryptOut_fields, &resp_msg)) {

                        if (ciphertext_byte_array->size <= output_size) {

                            memcpy(output, ciphertext_byte_array->bytes, ciphertext_byte_array->size);
                            *output_length = ciphertext_byte_array->size;
                        }
                        else {
                            /* Provided buffer is too small */
                            psa_status = PSA_ERROR_BUFFER_TOO_SMALL;
                        }
                    }
                    else {
                        /* Failed to decode response message */
                        psa_status = PSA_ERROR_GENERIC_ERROR;
                    }

                    ::free(ciphertext_byte_array);
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    ::free(plaintext_byte_array);
    ::free(salt_byte_array);

    return psa_status;
}

psa_status_t crypto_client::asymmetric_decrypt(psa_key_handle_t handle, psa_algorithm_t alg,
                        const uint8_t *input, size_t input_length,
                        const uint8_t *salt, size_t salt_length,
                        uint8_t *output, size_t output_size, size_t *output_length)
{
    size_t req_len;
    pb_bytes_array_t *ciphertext_byte_array = pb_malloc_byte_array_containing_bytes(input, input_length);
    pb_bytes_array_t *salt_byte_array = pb_malloc_byte_array_containing_bytes(salt, salt_length);
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_AsymmetricDecryptIn req_msg = ts_crypto_AsymmetricDecryptIn_init_default;

    *output_length = 0;  /* For failure case */

    req_msg.handle = handle;
    req_msg.alg = alg;
	req_msg.ciphertext = pb_out_byte_array(ciphertext_byte_array);
    req_msg.salt = pb_out_byte_array(salt_byte_array);

	if (pb_get_encoded_size(&req_len, ts_crypto_AsymmetricDecryptIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_AsymmetricDecryptIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                        ts_crypto_Opcode_ASYMMETRIC_DECRYPT, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    pb_bytes_array_t *plaintext_byte_array = pb_malloc_byte_array(output_size);
                    ts_crypto_AsymmetricDecryptOut resp_msg = ts_crypto_AsymmetricDecryptOut_init_default;
                    resp_msg.plaintext = pb_in_byte_array(plaintext_byte_array);

                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_AsymmetricDecryptOut_fields, &resp_msg)) {

                        if (plaintext_byte_array->size <= output_size) {

                            memcpy(output, plaintext_byte_array->bytes, plaintext_byte_array->size);
                            *output_length = plaintext_byte_array->size;
                        }
                        else {
                            /* Provided buffer is too small */
                            m_err_rpc_status = PSA_ERROR_BUFFER_TOO_SMALL;
                        }
                    }
                    else {
                        /* Failed to decode response message */
                        m_err_rpc_status = PSA_ERROR_GENERIC_ERROR;
                    }

                    ::free(plaintext_byte_array);
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    ::free(ciphertext_byte_array);
    ::free(salt_byte_array);

    return psa_status;
}

psa_status_t crypto_client::generate_random(uint8_t *output, size_t output_size)
{
    size_t req_len;
    psa_status_t psa_status = PSA_ERROR_GENERIC_ERROR;
    ts_crypto_GenerateRandomIn req_msg = ts_crypto_GenerateRandomIn_init_default;

    req_msg.size = output_size;

	if (pb_get_encoded_size(&req_len, ts_crypto_GenerateRandomIn_fields, &req_msg)) {

        rpc_call_handle call_handle;
        uint8_t *req_buf;

        call_handle = rpc_caller_begin(m_caller, &req_buf, req_len);

        if (call_handle) {

            uint8_t *resp_buf;
            size_t resp_len;
            int opstatus;

            pb_ostream_t ostream = pb_ostream_from_buffer(req_buf, req_len);
            pb_encode(&ostream, ts_crypto_GenerateRandomIn_fields, &req_msg);

            m_err_rpc_status = rpc_caller_invoke(m_caller, call_handle,
                    ts_crypto_Opcode_GENERATE_RANDOM, &opstatus, &resp_buf, &resp_len);

            if (m_err_rpc_status == TS_RPC_CALL_ACCEPTED) {

                psa_status = opstatus;

                if (psa_status == PSA_SUCCESS) {

                    pb_bytes_array_t *output_byte_array = pb_malloc_byte_array(output_size);
                    ts_crypto_GenerateRandomOut resp_msg = ts_crypto_GenerateRandomOut_init_default;
                    resp_msg.random_bytes = pb_in_byte_array(output_byte_array);

                    pb_istream_t istream = pb_istream_from_buffer(resp_buf, resp_len);

                    if (pb_decode(&istream, ts_crypto_GenerateRandomOut_fields, &resp_msg)) {

                        if (output_byte_array->size == output_size) {

                            memcpy(output, output_byte_array->bytes, output_byte_array->size);
                        }
                        else {
                            /* Mismatch between requested and generated length */
                            psa_status = PSA_ERROR_GENERIC_ERROR;
                        }
                    }
                    else {
                        /* Failed to decode response message */
                        psa_status = PSA_ERROR_GENERIC_ERROR;
                    }

                    ::free(output_byte_array);
                }
            }

            rpc_caller_end(m_caller, call_handle);
        }
    }

    return psa_status;
}

void crypto_client::translate_key_attributes(ts_crypto_KeyAttributes &proto_attributes,
                            const psa_key_attributes_t &psa_attributes)
{
    proto_attributes.type = psa_get_key_type(&psa_attributes);
    proto_attributes.key_bits = psa_get_key_bits(&psa_attributes);
    proto_attributes.lifetime = psa_get_key_lifetime(&psa_attributes);
    proto_attributes.id = psa_get_key_id(&psa_attributes);

    proto_attributes.has_policy = true;
    proto_attributes.policy.usage = psa_get_key_usage_flags(&psa_attributes);
    proto_attributes.policy.alg = psa_get_key_algorithm(&psa_attributes);
 }