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PKCS#7: add example to verify existing SignedData file
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‎.gitignore‎

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@@ -185,6 +185,8 @@ pkcs7/signedData-CompressedFirmwarePkgData
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pkcs7/signedData-EncryptedCompressedFirmwarePkgData
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pkcs7/signedData-EncryptedFirmwareCB
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pkcs7/signedData-p7b
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pkcs7/signedData-cryptocb
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pkcs7/signedData-verifyFile
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*.dSYM
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certmanager/certloadverifybuffer

‎pkcs7/README.md‎

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@@ -572,6 +572,50 @@ Successfully encoded Signed Encrypted Compressed FirmwarePkgData (signedEncrypte
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Successfully extracted and verified bundle contents
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```
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### Verify SignedData bundle from existing file
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Example file: `signedData-verifyFile.c`
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This example allows the caller to pass in an existing PKCS#7/CMS bundle
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in DER format, then attempts to verify the SignedData bundle using wolfCrypt.
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Usage for this example is:
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```
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signedData-verifyFile X.X.X (NOTE: All files relative to current directory)
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-? Help, print this usage
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-b <file> PKCS#7/CMS bundle to verify (DER format)
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-c <content> Detached content, if needed
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```
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If wolfSSL has been configured and compiled with debug support, the bytes
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of the bundle will be printed out to the terminal window. For example to verify
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the bundle created by the `signedData` example:
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```
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./signedData-verifyFile -b signedData_noattrs.der
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wolfCrypt PKCS#7/CMS SignedData verification example
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Read 1982 bytes from signedData_noattrs.der
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Decoded content size is 11 bytes
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Successfully verified SignedData bundle!
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```
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To verify SignedData bundles that represent a detached signature (which does
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not include content in the bundle), use the `-c` option to pass in a file to
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be used as the content. For example, to verify the bundle created by the
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example application `signedData-DetachedSignature`:
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```
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./signedData-verifyFile -b signedData_detached_attrs.der -c content.txt
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wolfCrypt PKCS#7/CMS SignedData verification example
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Read 1987 bytes from signedData_detached_attrs.der
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Read 11 bytes from content file: content.txt
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Decoded content size is 11 bytes
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Successfully verified SignedData bundle!
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```
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### Converting P7B Certificate Bundle to PEM using PKCS7 SignedData API
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Build wolfssl using: `./configure --enable-pkcs7 CFLAGS="-DWOLFSSL_DER_TO_PEM"`

‎pkcs7/signedData-verifyFile.c‎

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/* signedData-verifyFile.c
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*
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* Copyright (C) 2006-2023 wolfSSL Inc.
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*
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* This file is part of wolfSSL. (formerly known as CyaSSL)
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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 02110-1301, USA
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*/
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#include <wolfssl/options.h>
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#include <wolfssl/wolfcrypt/settings.h>
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#include <wolfssl/wolfcrypt/pkcs7.h>
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#include <wolfssl/wolfcrypt/error-crypt.h>
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#include <wolfssl/wolfcrypt/logging.h>
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#include <wolfssl/ssl.h>
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#include <wolfssl/test.h>
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/* Max PEM cert size, used to allocate memory below. Change as needed
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* for your expected PEM certificate sizes */
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#define MAX_PEM_CERT_SIZE 4096
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/* The index of the command line option */
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int myoptind = 0;
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/* The current command line option */
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char* myoptarg = NULL;
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/**
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* Verify PKCS#7/CMS bundle contained in bundleBytes, of size bundleSz.
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*
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* Return 0 on success, negative on error
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*/
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static int VerifySignedData(byte* bundleBytes, word32 bundleSz,
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byte* detachedContent, word32 detachedContentSz)
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{
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int ret, i;
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PKCS7* pkcs7 = NULL;
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byte* singleCertDer; /* tmp ptr to one DER cert in decoded PKCS7 */
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word32 singleCertDerSz; /* tmp size of one DER cert in decoded PKCS7 */
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#ifdef WOLFSSL_DER_TO_PEM
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byte* singleCertPem;
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word32 singleCertPemSz;
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#endif
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(void)singleCertDer;
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if (bundleBytes == NULL || bundleSz == 0) {
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return BAD_FUNC_ARG;
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}
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pkcs7 = wc_PKCS7_New(NULL, INVALID_DEVID);
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if (pkcs7 == NULL) {
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printf("wc_PKCS7_New failed\n");
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return -1;
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}
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if (detachedContent != NULL) {
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pkcs7->content = detachedContent;
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pkcs7->contentSz = detachedContentSz;
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}
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/* Decode signedData, returns size */
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ret = wc_PKCS7_VerifySignedData(pkcs7, bundleBytes, bundleSz);
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if (ret < 0) {
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wc_PKCS7_Free(pkcs7);
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return ret;
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}
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#ifdef DEBUG_WOLFSSL
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printf("Decoded content (%d bytes):\n", pkcs7->contentSz);
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WOLFSSL_BUFFER(pkcs7->content, pkcs7->contentSz);
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#else
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printf("Decoded content size is %d bytes\n", pkcs7->contentSz);
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#endif
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/* wc_PKCS7_VerifySignedData() decodes input PKCS#7 and stores
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* decoded DER certificates into pkcs7->cert[]. Sizes of each cert entry
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* is stored in the separate pkcs7->certSz[] array. Max size of each
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* of the arrays is MAX_PKCS7_CERTS. Array memory is owned by wolfCrypt
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* PKCS7 and freed when calling wc_PKCS7_Free(). */
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for (i = 0; i < MAX_PKCS7_CERTS; i++) {
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if (pkcs7->certSz[i] == 0) {
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/* reached end of valid certs in array */
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break;
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}
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singleCertDer = pkcs7->cert[i];
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singleCertDerSz = pkcs7->certSz[i];
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printf("CERT [%d] size = %d bytes\n", i, singleCertDerSz);
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#ifdef WOLFSSL_DER_TO_PEM
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/* allocate array for PEM */
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singleCertPem = (byte*)XMALLOC(MAX_PEM_CERT_SIZE, NULL,
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DYNAMIC_TYPE_TMP_BUFFER);
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if (singleCertPem == NULL) {
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printf("Error allocating memory for PEM\n");
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break;
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}
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singleCertPemSz = MAX_PEM_CERT_SIZE;
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XMEMSET(singleCertPem, 0, singleCertPemSz);
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/* convert DER to PEM */
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singleCertPemSz = wc_DerToPem(singleCertDer, singleCertDerSz,
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singleCertPem, singleCertPemSz,
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CERT_TYPE);
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if (singleCertPem < 0) {
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printf("Error converting DER to PEM, ret = %d\n", ret);
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XFREE(singleCertPem, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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break;
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}
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printf("converted DER to PEM, pemSz = %d\n", singleCertPemSz);
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printf("CERT [%d] PEM:\n", i);
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/* print PEM to terminal, only if able to NULL terminate */
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if (singleCertPemSz < MAX_PEM_CERT_SIZE - 1) {
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singleCertPem[singleCertPemSz] = 0;
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printf("%s\n", singleCertPem);
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}
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/* PEM is now in singleCertPem, of size singleCertPemSz */
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XFREE(singleCertPem, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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#endif /* WOLFSSL_DER_TO_PEM */
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}
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wc_PKCS7_Free(pkcs7);
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return ret;
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}
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#ifdef HAVE_PKCS7
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/**
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* Read file into newly-allocated buffer fileBytes, set size of allocated
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* buffer into fileSz.
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*
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* Return 0 on success, negative on error
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*/
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static int ReadFile(char* fileName, byte** fileBytes, word32* fileSz)
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{
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int ret = 0;
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FILE* fp = NULL;
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word32 sz = 0;
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if (fileName == NULL || fileBytes == NULL || fileSz == NULL) {
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return -1;
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}
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fp = XFOPEN(fileName, "rb");
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if (fp == XBADFILE) {
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return -1;
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}
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if (XFSEEK(fp, 0, XSEEK_END) != 0) {
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ret = -1;
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}
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if (ret == 0) {
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sz = XFTELL(fp);
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if (sz <= 0) {
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ret = -1;
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}
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}
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if (ret == 0) {
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if (XFSEEK(fp, 0, XSEEK_SET) != 0) {
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ret = -1;
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}
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}
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if (ret == 0) {
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*fileBytes = (byte*)XMALLOC(sz, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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if (*fileBytes == NULL) {
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ret = MEMORY_E;
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}
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else {
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XMEMSET(*fileBytes, 0, sz);
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*fileSz = sz;
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}
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}
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if (ret == 0) {
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if ((size_t)XFREAD(*fileBytes, 1, (size_t)sz, fp) != (size_t)sz) {
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ret = -1;
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}
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}
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if (fp != XBADFILE) {
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XFCLOSE(fp);
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}
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return ret;
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}
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static void Usage(void)
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{
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printf("signedData-verifyFile " LIBWOLFSSL_VERSION_STRING
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" (NOTE: All files relative to current directory)\n");
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printf("-? Help, print this usage\n");
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printf("-b <file> PKCS#7/CMS bundle to verify (DER format)\n");
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printf("-c <content> Detached content, if needed\n");
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}
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int main(int argc, char** argv)
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{
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int ret = 0;
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int ch = 0;
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char* bundleFile = NULL;
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byte* bundleBytes = NULL;
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word32 bundleSz = 0;
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char* detachedContentFile = NULL;
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byte* detachedContentBytes = NULL;
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word32 detachedContentSz = 0;
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printf("wolfCrypt PKCS#7/CMS SignedData verification example\n\n");
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while ((ch = mygetopt(argc, argv, "?b:c:")) != -1) {
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switch (ch) {
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case '?':
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Usage();
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exit(EXIT_SUCCESS);
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/* File containing PKCS#7/CMS bundle */
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case 'b':
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bundleFile = myoptarg;
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break;
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case 'c':
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detachedContentFile = myoptarg;
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break;
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default:
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Usage();
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exit(MY_EX_USAGE);
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}
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}
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#ifdef DEBUG_WOLFSSL
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wolfSSL_Debugging_ON();
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#endif
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wolfSSL_Init();
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/* Read PKCS#7 bundle file into array */
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ret = ReadFile(bundleFile, &bundleBytes, &bundleSz);
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if (ret == 0) {
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printf("Read %d bytes from %s\n", bundleSz, bundleFile);
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}
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else {
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printf("Failed to read bundle file: %s\n", bundleFile);
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}
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/* Read detached content file into array, if given */
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if (ret == 0 && detachedContentFile != NULL) {
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ret = ReadFile(detachedContentFile, &detachedContentBytes,
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&detachedContentSz);
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if (ret == 0) {
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printf("Read %d bytes from content file: %s\n",
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detachedContentSz, detachedContentFile);
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}
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else {
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printf("Failed to read content file: %s\n", detachedContentFile);
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}
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}
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/* Verify PKCS#7/CMS SignedData bundle */
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if (ret == 0) {
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ret = VerifySignedData(bundleBytes, bundleSz,
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detachedContentBytes, detachedContentSz);
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if (ret == 0) {
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printf("Successfully verified SignedData bundle!\n");
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}
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else {
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printf("Failed to verify SignedData bundle, ret = %d\n", ret);
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}
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}
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/* Free detached content array, allocated by ReadFile() */
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if (detachedContentBytes != NULL) {
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XMEMSET(detachedContentBytes, 0, detachedContentSz);
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XFREE(detachedContentBytes, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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}
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/* Free bundle array, allocated by ReadFile() */
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if (bundleBytes != NULL) {
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XMEMSET(bundleBytes, 0, bundleSz);
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XFREE(bundleBytes, NULL, DYNAMIC_TYPE_TMP_BUFFER);
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}
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wolfSSL_Cleanup();
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exit(EXIT_SUCCESS);
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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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printf("Must build wolfSSL using ./configure --enable-pkcs7\n");
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return 0;
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}
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#endif /* HAVE_PKCS7 */
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