<div dir="ltr"><div>Xiaobin,</div><div><br></div>Here's what I came up with:<div><br></div><div> crypto:start(),</div><div><div> %% To decrypt the text, note Key and IV must be defined in this scope</div><div> Unencoded = base64:decode(Value),</div><div> Cleartext = crypto:block_decrypt(des3_cbc, Key, IV, Unencoded),</div><div> %% To unpad the text, see <a href="https://github.com/camshaft/pkcs7.erl">https://github.com/camshaft/pkcs7.erl</a></div><div> pkcs7:unpad(Cleartext)</div></div><div><br></div><div>The main thing to note is the difference in how you use the crypto module. In Erlang, you don't need to initialize, decrypt, and cleanup in separate steps. You do however, need to make sure the crypto application is started before you try this. Generally, you would make crypto a dependency (see <a href="http://erlang.org/doc/man/app.html">http://erlang.org/doc/man/app.html</a>) of the application that contains this code and it would be started automatically when your release is booted.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Aug 10, 2015 at 7:59 AM, Xiaobin Xu <span dir="ltr"><<a href="mailto:xuxb1979@gmail.com" target="_blank">xuxb1979@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi, all,<div><br></div><div> For some reason i have to decrypt a message that is encrypted using 3DES algorithm, and I've PHP function example how to decrypt the message:</div><div><br></div><div><div><span style="white-space:pre-wrap"> </span>public function decrypt($value) {</div><div><span style="white-space:pre-wrap"> </span>$td = mcrypt_module_open ( MCRYPT_3DES, '', MCRYPT_MODE_ECB, '' );</div><div><span style="white-space:pre-wrap"> </span>mcrypt_generic_init ( $td, $this->key,$this->iv );</div><div><span style="white-space:pre-wrap"> </span>$ret = trim ( mdecrypt_generic ( $td, base64_decode ( $value ) ) );</div><div><span style="white-space:pre-wrap"> </span>$ret = $this->UnPaddingPKCS7 ( $ret );</div><div><span style="white-space:pre-wrap"> </span>mcrypt_generic_deinit ( $td );</div><div><span style="white-space:pre-wrap"> </span>mcrypt_module_close ( $td );</div><div><span style="white-space:pre-wrap"> </span>return $ret;</div><div><span style="white-space:pre-wrap"> </span>}</div><div><span style="white-space:pre-wrap"> </span> </div><div><span style="white-space:pre-wrap"> </span> </div><div><span style="white-space:pre-wrap"> </span>private function UnPaddingPKCS7($data) {</div><div><span style="white-space:pre-wrap"> </span>$padlen = ord (substr($data, (strlen( $data )-1), 1 ) );</div><div><span style="white-space:pre-wrap"> </span>if ($padlen > 8 )</div><div><span style="white-space:pre-wrap"> </span>return $data;</div><div><span style="white-space:pre-wrap"> </span> </div><div><span style="white-space:pre-wrap"> </span>for($i = -1*($padlen-strlen($data)); $i < strlen ( $data ); $i ++) {</div><div><span style="white-space:pre-wrap"> </span>if (ord ( substr ( $data, $i, 1 ) ) != $padlen)return false;</div><div><span style="white-space:pre-wrap"> </span>}</div><div><span style="white-space:pre-wrap"> </span> </div><div><span style="white-space:pre-wrap"> </span>return substr ( $data, 0, -1*($padlen-strlen ( $data ) ) );</div><div><span style="white-space:pre-wrap"> </span>}</div></div><div><br></div><div> I googled and read crypto module document for a couple hours, and got no idea how to translate these two functions into erlang.</div><div><br></div><div> Any ideas?</div><div><br></div><div><br></div><div> Thanks, </div><span class="HOEnZb"><font color="#888888"><div> Xiaobin</div><div><br></div></font></span></div>
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