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<title>Heimdal crypto library: example_evp_cipher.c</title>
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<h1>example_evp_cipher.c</h1>This is an example how to use <a class="el" href="group__hcrypto__evp.html#g98da5a5c1aa25d9cb2e4717fa11314bd">EVP_CipherInit_ex()</a>, <a class="el" href="group__hcrypto__evp.html#g863349e1001b36cfd6c4afedddd12862">EVP_CipherUpdate()</a> and <a class="el" href="group__hcrypto__evp.html#g714eef7d737fd68171d852043a4995de">EVP_CipherFinal_ex()</a>.<p>
<div class="fragment"><pre class="fragment"><span class="comment">/*</span>
<span class="comment"> * Copyright (c) 2008 Kungliga Tekniska Högskolan</span>
<span class="comment"> * (Royal Institute of Technology, Stockholm, Sweden).</span>
<span class="comment"> * All rights reserved.</span>
<span class="comment"> *</span>
<span class="comment"> * Redistribution and use in source and binary forms, with or without</span>
<span class="comment"> * modification, are permitted provided that the following conditions</span>
<span class="comment"> * are met:</span>
<span class="comment"> *</span>
<span class="comment"> * 1. Redistributions of source code must retain the above copyright</span>
<span class="comment"> * notice, this list of conditions and the following disclaimer.</span>
<span class="comment"> *</span>
<span class="comment"> * 2. Redistributions in binary form must reproduce the above copyright</span>
<span class="comment"> * notice, this list of conditions and the following disclaimer in the</span>
<span class="comment"> * documentation and/or other materials provided with the distribution.</span>
<span class="comment"> *</span>
<span class="comment"> * 3. Neither the name of the Institute nor the names of its contributors</span>
<span class="comment"> * may be used to endorse or promote products derived from this software</span>
<span class="comment"> * without specific prior written permission.</span>
<span class="comment"> *</span>
<span class="comment"> * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND</span>
<span class="comment"> * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE</span>
<span class="comment"> * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE</span>
<span class="comment"> * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE</span>
<span class="comment"> * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL</span>
<span class="comment"> * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS</span>
<span class="comment"> * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)</span>
<span class="comment"> * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT</span>
<span class="comment"> * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY</span>
<span class="comment"> * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF</span>
<span class="comment"> * SUCH DAMAGE.</span>
<span class="comment"> */</span>
<span class="preprocessor">#include <krb5-types.h></span> <span class="comment">/* should really be stdint.h */</span>
<span class="preprocessor">#include <hcrypto/evp.h></span>
<span class="preprocessor">#include <stdio.h></span>
<span class="preprocessor">#include <stdlib.h></span>
<span class="preprocessor">#include <string.h></span>
<span class="preprocessor">#include <err.h></span>
<span class="preprocessor">#include <assert.h></span>
<span class="preprocessor">#include "roken.h"</span>
<span class="comment">/* key and initial vector */</span>
<span class="keyword">static</span> <span class="keywordtype">char</span> key[16] =
<span class="stringliteral">"\xaa\xbb\x45\xd4\xaa\xbb\x45\xd4"</span>
<span class="stringliteral">"\xaa\xbb\x45\xd4\xaa\xbb\x45\xd4"</span>;
<span class="keyword">static</span> <span class="keywordtype">char</span> ivec[16] =
<span class="stringliteral">"\xaa\xbb\x45\xd4\xaa\xbb\x45\xd4"</span>
<span class="stringliteral">"\xaa\xbb\x45\xd4\xaa\xbb\x45\xd4"</span>;
<span class="keyword">static</span> <span class="keywordtype">void</span>
usage(<span class="keywordtype">int</span> exit_code) __attribute__((noreturn));
<span class="keyword">static</span> <span class="keywordtype">void</span>
usage(<span class="keywordtype">int</span> exit_code)
{
printf(<span class="stringliteral">"usage: %s in out\n"</span>, getprogname());
exit(exit_code);
}
<span class="keywordtype">int</span>
main(<span class="keywordtype">int</span> argc, <span class="keywordtype">char</span> **argv)
{
<span class="keywordtype">int</span> encryptp = 1;
<span class="keyword">const</span> <span class="keywordtype">char</span> *ifn = NULL, *ofn = NULL;
FILE *in, *out;
<span class="keywordtype">void</span> *ibuf, *obuf;
<span class="keywordtype">int</span> ilen, olen;
<span class="keywordtype">size_t</span> block_size = 0;
<span class="keyword">const</span> EVP_CIPHER *c = <a name="a0"></a><a class="code" href="group__hcrypto__evp.html#g2747bac943db15c97167ac37fdc2af43">EVP_aes_128_cbc</a>();
EVP_CIPHER_CTX ctx;
<span class="keywordtype">int</span> ret;
setprogname(argv[0]);
<span class="keywordflow">if</span> (argc == 2) {
<span class="keywordflow">if</span> (strcmp(argv[1], <span class="stringliteral">"--version"</span>) == 0) {
printf(<span class="stringliteral">"version"</span>);
exit(0);
}
<span class="keywordflow">if</span> (strcmp(argv[1], <span class="stringliteral">"--help"</span>) == 0)
usage(0);
usage(1);
} <span class="keywordflow">else</span> <span class="keywordflow">if</span> (argc == 4) {
block_size = atoi(argv[1]);
<span class="keywordflow">if</span> (block_size == 0)
errx(1, <span class="stringliteral">"invalid blocksize %s"</span>, argv[1]);
ifn = argv[2];
ofn = argv[3];
} <span class="keywordflow">else</span>
usage(1);
in = fopen(ifn, <span class="stringliteral">"r"</span>);
<span class="keywordflow">if</span> (in == NULL)
errx(1, <span class="stringliteral">"failed to open input file"</span>);
out = fopen(ofn, <span class="stringliteral">"w+"</span>);
<span class="keywordflow">if</span> (out == NULL)
errx(1, <span class="stringliteral">"failed to open output file"</span>);
<span class="comment">/* Check that key and ivec are long enough */</span>
assert(<a name="a1"></a><a class="code" href="group__hcrypto__evp.html#g4793a9e130da86ac42c497b19395b748">EVP_CIPHER_key_length</a>(c) <= <span class="keyword">sizeof</span>(key));
assert(<a name="a2"></a><a class="code" href="group__hcrypto__evp.html#g7edebe76d19dee11686a6698d24f19f5">EVP_CIPHER_iv_length</a>(c) <= <span class="keyword">sizeof</span>(ivec));
<span class="comment">/*</span>
<span class="comment"> * Allocate buffer, the output buffer is at least</span>
<span class="comment"> * EVP_CIPHER_block_size() longer</span>
<span class="comment"> */</span>
ibuf = malloc(block_size);
obuf = malloc(block_size + <a name="a3"></a><a class="code" href="group__hcrypto__evp.html#g3123ff4b426783dd972538249b9e9d4d">EVP_CIPHER_block_size</a>(c));
<span class="comment">/*</span>
<span class="comment"> * Init the memory used for EVP_CIPHER_CTX and set the key and</span>
<span class="comment"> * ivec.</span>
<span class="comment"> */</span>
<a name="a4"></a><a class="code" href="group__hcrypto__evp.html#g13d0ff0e87312566cb6b3591157f9754">EVP_CIPHER_CTX_init</a>(&ctx);
<a name="a5"></a><a class="code" href="group__hcrypto__evp.html#g98da5a5c1aa25d9cb2e4717fa11314bd">EVP_CipherInit_ex</a>(&ctx, c, NULL, key, ivec, encryptp);
<span class="comment">/* read in buffer */</span>
<span class="keywordflow">while</span> ((ilen = fread(ibuf, 1, block_size, in)) > 0) {
<span class="comment">/* encrypto/decrypt */</span>
ret = <a name="a6"></a><a class="code" href="group__hcrypto__evp.html#g863349e1001b36cfd6c4afedddd12862">EVP_CipherUpdate</a>(&ctx, obuf, &olen, ibuf, ilen);
<span class="keywordflow">if</span> (ret != 1) {
<a name="a7"></a><a class="code" href="group__hcrypto__evp.html#gc16dd3987cd90c8bcdbad5290c558359">EVP_CIPHER_CTX_cleanup</a>(&ctx);
errx(1, <span class="stringliteral">"EVP_CipherUpdate failed"</span>);
}
<span class="comment">/* write out to output file */</span>
fwrite(obuf, 1, olen, out);
}
<span class="comment">/* done reading */</span>
fclose(in);
<span class="comment">/* clear up any last bytes left in the output buffer */</span>
ret = <a name="a8"></a><a class="code" href="group__hcrypto__evp.html#g714eef7d737fd68171d852043a4995de">EVP_CipherFinal_ex</a>(&ctx, obuf, &olen);
<a class="code" href="group__hcrypto__evp.html#gc16dd3987cd90c8bcdbad5290c558359">EVP_CIPHER_CTX_cleanup</a>(&ctx);
<span class="keywordflow">if</span> (ret != 1)
errx(1, <span class="stringliteral">"EVP_CipherFinal_ex failed"</span>);
<span class="comment">/* write the last bytes out and close */</span>
fwrite(obuf, 1, olen, out);
fclose(out);
<span class="keywordflow">return</span> 0;
}
</pre></div> </div>
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