283 lines
8.0 KiB
C
283 lines
8.0 KiB
C
/* aes-keywrap.c
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*
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* Copyright (C) 2006-2025 wolfSSL Inc.
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*
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* This file is part of wolfSSL.
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*
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* wolfSSL is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* wolfSSL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
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*/
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/* AES-KEYWRAP Example
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* This example demonstrates:
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* - One-shot key wrapping using wc_AesKeyWrap()
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* - One-shot key unwrapping using wc_AesKeyUnWrap()
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* Note: Key wrap is designed for wrapping cryptographic keys
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* Input must be multiple of 8 bytes (64 bits)
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* No streaming API available
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#ifndef WOLFSSL_USER_SETTINGS
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#include <wolfssl/options.h>
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#endif
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#include <wolfssl/wolfcrypt/settings.h>
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#include <wolfssl/wolfcrypt/aes.h>
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#include <wolfssl/wolfcrypt/error-crypt.h>
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#include <wolfssl/wolfcrypt/memory.h>
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#if !defined(NO_AES) && defined(HAVE_AES_KEYWRAP)
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#define AES_KEY_SIZE AES_256_KEY_SIZE
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/* Key wrap block size */
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#define KEYWRAP_BLOCK 8
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static int read_file(const char* filename, byte** data, word32* dataSz)
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{
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FILE* fp;
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long fileSz;
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fp = fopen(filename, "rb");
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if (fp == NULL) {
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printf("Error: Cannot open file %s\n", filename);
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return -1;
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}
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fseek(fp, 0, SEEK_END);
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fileSz = ftell(fp);
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fseek(fp, 0, SEEK_SET);
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*data = (byte*)XMALLOC(fileSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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if (*data == NULL) {
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fclose(fp);
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printf("Error: Memory allocation failed\n");
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return -1;
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}
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*dataSz = (word32)fread(*data, 1, fileSz, fp);
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fclose(fp);
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return 0;
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}
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static int write_file(const char* filename, const byte* data, word32 dataSz)
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{
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FILE* fp;
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fp = fopen(filename, "wb");
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if (fp == NULL) {
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printf("Error: Cannot create file %s\n", filename);
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return -1;
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}
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fwrite(data, 1, dataSz, fp);
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fclose(fp);
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return 0;
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}
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/* One-shot key wrapping */
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static int wrap_file(const char* inFile, const char* outFile,
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const byte* key, word32 keySz)
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{
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byte* plaintext = NULL;
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byte* wrapped = NULL;
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word32 plaintextSz;
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word32 paddedSz;
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word32 wrappedSz;
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word32 padLen;
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int ret;
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ret = read_file(inFile, &plaintext, &plaintextSz);
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if (ret != 0) return ret;
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/* Key wrap requires input to be multiple of 8 bytes */
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padLen = (KEYWRAP_BLOCK - (plaintextSz % KEYWRAP_BLOCK)) % KEYWRAP_BLOCK;
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paddedSz = plaintextSz + padLen;
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/* Wrapped output is input + 8 bytes (integrity check value) */
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/* Also store original size (4 bytes) at beginning */
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wrappedSz = 4 + paddedSz + KEYWRAP_BLOCK;
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wrapped = (byte*)XMALLOC(wrappedSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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if (wrapped == NULL) {
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wc_ForceZero(plaintext, plaintextSz);
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XFREE(plaintext, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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return -1;
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}
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/* Apply padding if needed */
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if (padLen > 0) {
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byte* tmp = (byte*)XREALLOC(plaintext, paddedSz, NULL,
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DYNAMIC_TYPE_TMP_BUFFER);
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if (tmp == NULL) {
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wc_ForceZero(plaintext, plaintextSz);
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XFREE(plaintext, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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return -1;
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}
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plaintext = tmp;
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XMEMSET(plaintext + plaintextSz, 0, padLen);
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}
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/* One-shot key wrap */
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ret = wc_AesKeyWrap(key, keySz, plaintext, paddedSz,
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wrapped + 4, wrappedSz - 4, NULL);
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if (ret < 0) {
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wc_ForceZero(plaintext, paddedSz);
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XFREE(plaintext, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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return ret;
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}
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/* Store original size at beginning */
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wrapped[0] = (byte)(plaintextSz >> 24);
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wrapped[1] = (byte)(plaintextSz >> 16);
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wrapped[2] = (byte)(plaintextSz >> 8);
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wrapped[3] = (byte)(plaintextSz);
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ret = write_file(outFile, wrapped, wrappedSz);
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wc_ForceZero(plaintext, paddedSz);
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XFREE(plaintext, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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printf("AES-KEYWRAP wrapping complete (one-shot)\n");
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return ret;
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}
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/* One-shot key unwrapping (no streaming API available) */
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static int unwrap_file(const char* inFile, const char* outFile,
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const byte* key, word32 keySz)
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{
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byte* wrapped = NULL;
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byte* plaintext = NULL;
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word32 wrappedSz;
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word32 plaintextSz;
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word32 originalSz;
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int ret;
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ret = read_file(inFile, &wrapped, &wrappedSz);
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if (ret != 0) return ret;
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if (wrappedSz < 4 + KEYWRAP_BLOCK * 2) {
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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printf("Error: File too small\n");
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return -1;
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}
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/* Extract original size from beginning */
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originalSz = ((word32)wrapped[0] << 24) |
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((word32)wrapped[1] << 16) |
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((word32)wrapped[2] << 8) |
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((word32)wrapped[3]);
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/* Unwrapped size is wrapped - 4 (size header) - 8 (integrity check) */
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plaintextSz = wrappedSz - 4 - KEYWRAP_BLOCK;
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if (originalSz > plaintextSz) {
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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printf("Error: Invalid decrypted size\n");
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return -1;
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}
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plaintext = (byte*)XMALLOC(plaintextSz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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if (plaintext == NULL) {
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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return -1;
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}
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/* One-shot key unwrap */
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ret = wc_AesKeyUnWrap(key, keySz, wrapped + 4, wrappedSz - 4,
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plaintext, plaintextSz, NULL);
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if (ret < 0) {
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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wc_ForceZero(plaintext, plaintextSz);
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XFREE(plaintext, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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printf("Error: Key unwrap failed (integrity check may have failed)\n");
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return ret;
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}
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/* Use original size to remove padding */
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ret = write_file(outFile, plaintext, originalSz);
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XFREE(wrapped, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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wc_ForceZero(plaintext, plaintextSz);
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XFREE(plaintext, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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printf("AES-KEYWRAP unwrapping complete (one-shot, no streaming API "
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"available)\n");
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return ret;
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}
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int main(int argc, char** argv)
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{
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byte key[AES_KEY_SIZE];
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int ret;
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if (argc != 3) {
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printf("Usage: %s <input file> <output file>\n", argv[0]);
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printf("Wraps input file, then unwraps to output file\n");
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printf("Note: Key wrap is designed for wrapping cryptographic keys\n");
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return 1;
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}
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wolfCrypt_Init();
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/* Use a fixed key for demonstration */
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XMEMSET(key, 0x0C, AES_KEY_SIZE);
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/* Wrap to temporary file */
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ret = wrap_file(argv[1], "temp_wrapped.bin", key, AES_KEY_SIZE);
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if (ret != 0) {
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printf("Wrapping failed: %d\n", ret);
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wc_ForceZero(key, AES_KEY_SIZE);
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wolfCrypt_Cleanup();
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return 1;
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}
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/* Unwrap to output file */
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ret = unwrap_file("temp_wrapped.bin", argv[2], key, AES_KEY_SIZE);
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if (ret != 0) {
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printf("Unwrapping failed: %d\n", ret);
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wc_ForceZero(key, AES_KEY_SIZE);
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wolfCrypt_Cleanup();
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return 1;
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}
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/* Clean up temp file */
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remove("temp_wrapped.bin");
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printf("Success! Unwrapped file written to %s\n", argv[2]);
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wc_ForceZero(key, AES_KEY_SIZE);
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wolfCrypt_Cleanup();
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return 0;
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}
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#else
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int main(int argc, char** argv)
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{
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(void)argc;
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(void)argv;
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printf("AES-KEYWRAP not compiled in. Enable with HAVE_AES_KEYWRAP\n");
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return 0;
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}
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#endif
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