tools: Add firmware authenticated encryption tool
Add firmware authenticated encryption tool which utilizes OpenSSL
library to encrypt firmwares using a key provided via cmdline. Currently
this tool supports AES-GCM as an authenticated encryption algorithm.
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Change-Id: I60e296af1b98f1912a19d5f91066be7ea85836e4
diff --git a/tools/encrypt_fw/src/encrypt.c b/tools/encrypt_fw/src/encrypt.c
new file mode 100644
index 0000000..18a514c
--- /dev/null
+++ b/tools/encrypt_fw/src/encrypt.c
@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2019, Linaro Limited. All rights reserved.
+ * Author: Sumit Garg <sumit.garg@linaro.org>
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <firmware_encrypted.h>
+#include <openssl/evp.h>
+#include <stdio.h>
+#include <string.h>
+#include "debug.h"
+#include "encrypt.h"
+
+#define BUFFER_SIZE 256
+#define IV_SIZE 12
+#define IV_STRING_SIZE 24
+#define TAG_SIZE 16
+#define KEY_SIZE 32
+#define KEY_STRING_SIZE 64
+
+static int gcm_encrypt(unsigned short fw_enc_status, char *key_string,
+ char *nonce_string, const char *ip_name,
+ const char *op_name)
+{
+ FILE *ip_file;
+ FILE *op_file;
+ EVP_CIPHER_CTX *ctx;
+ unsigned char data[BUFFER_SIZE], enc_data[BUFFER_SIZE];
+ unsigned char key[KEY_SIZE], iv[IV_SIZE], tag[TAG_SIZE];
+ int bytes, enc_len = 0, i, j, ret = 0;
+ struct fw_enc_hdr header;
+
+ memset(&header, 0, sizeof(struct fw_enc_hdr));
+
+ if (strlen(key_string) != KEY_STRING_SIZE) {
+ ERROR("Unsupported key size: %lu\n", strlen(key_string));
+ return -1;
+ }
+
+ for (i = 0, j = 0; i < KEY_SIZE; i++, j += 2) {
+ if (sscanf(&key_string[j], "%02hhx", &key[i]) != 1) {
+ ERROR("Incorrect key format\n");
+ return -1;
+ }
+ }
+
+ if (strlen(nonce_string) != IV_STRING_SIZE) {
+ ERROR("Unsupported IV size: %lu\n", strlen(nonce_string));
+ return -1;
+ }
+
+ for (i = 0, j = 0; i < IV_SIZE; i++, j += 2) {
+ if (sscanf(&nonce_string[j], "%02hhx", &iv[i]) != 1) {
+ ERROR("Incorrect IV format\n");
+ return -1;
+ }
+ }
+
+ ip_file = fopen(ip_name, "rb");
+ if (ip_file == NULL) {
+ ERROR("Cannot read %s\n", ip_name);
+ return -1;
+ }
+
+ op_file = fopen(op_name, "wb");
+ if (op_file == NULL) {
+ ERROR("Cannot write %s\n", op_name);
+ fclose(ip_file);
+ return -1;
+ }
+
+ ret = fseek(op_file, sizeof(struct fw_enc_hdr), SEEK_SET);
+ if (ret) {
+ ERROR("fseek failed\n");
+ goto out_file;
+ }
+
+ ctx = EVP_CIPHER_CTX_new();
+ if (ctx == NULL) {
+ ERROR("EVP_CIPHER_CTX_new failed\n");
+ ret = -1;
+ goto out_file;
+ }
+
+ ret = EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, NULL, NULL);
+ if (ret != 1) {
+ ERROR("EVP_EncryptInit_ex failed\n");
+ ret = -1;
+ goto out;
+ }
+
+ ret = EVP_EncryptInit_ex(ctx, NULL, NULL, key, iv);
+ if (ret != 1) {
+ ERROR("EVP_EncryptInit_ex failed\n");
+ goto out;
+ }
+
+ while ((bytes = fread(data, 1, BUFFER_SIZE, ip_file)) != 0) {
+ ret = EVP_EncryptUpdate(ctx, enc_data, &enc_len, data, bytes);
+ if (ret != 1) {
+ ERROR("EVP_EncryptUpdate failed\n");
+ ret = -1;
+ goto out;
+ }
+
+ fwrite(enc_data, 1, enc_len, op_file);
+ }
+
+ ret = EVP_EncryptFinal_ex(ctx, enc_data, &enc_len);
+ if (ret != 1) {
+ ERROR("EVP_EncryptFinal_ex failed\n");
+ ret = -1;
+ goto out;
+ }
+
+ ret = EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, TAG_SIZE, tag);
+ if (ret != 1) {
+ ERROR("EVP_CIPHER_CTX_ctrl failed\n");
+ ret = -1;
+ goto out;
+ }
+
+ header.magic = ENC_HEADER_MAGIC;
+ header.flags |= fw_enc_status & FW_ENC_STATUS_FLAG_MASK;
+ header.dec_algo = KEY_ALG_GCM;
+ header.iv_len = IV_SIZE;
+ header.tag_len = TAG_SIZE;
+ memcpy(header.iv, iv, IV_SIZE);
+ memcpy(header.tag, tag, TAG_SIZE);
+
+ ret = fseek(op_file, 0, SEEK_SET);
+ if (ret) {
+ ERROR("fseek failed\n");
+ goto out;
+ }
+
+ fwrite(&header, 1, sizeof(struct fw_enc_hdr), op_file);
+
+out:
+ EVP_CIPHER_CTX_free(ctx);
+
+out_file:
+ fclose(ip_file);
+ fclose(op_file);
+
+ /*
+ * EVP_* APIs returns 1 as success but enctool considers
+ * 0 as success.
+ */
+ if (ret == 1)
+ ret = 0;
+
+ return ret;
+}
+
+int encrypt_file(unsigned short fw_enc_status, int enc_alg, char *key_string,
+ char *nonce_string, const char *ip_name, const char *op_name)
+{
+ switch (enc_alg) {
+ case KEY_ALG_GCM:
+ return gcm_encrypt(fw_enc_status, key_string, nonce_string,
+ ip_name, op_name);
+ default:
+ return -1;
+ }
+}