mcrypt.constants.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Predefined Constants</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="mcrypt.resources.html">Resource Types</a></div> <div class="next" style="text-align: right; float: right;"><a href="mcrypt.ciphers.html">Mcrypt ciphers</a></div> <div class="up"><a href="book.mcrypt.html">Mcrypt</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div> <h1>Predefined Constants</h1> <p class="simpara">The constants below are defined by this extension, andwill only be available when the extension has eitherbeen compiled into PHP or dynamically loaded at runtime.</p> <p class="para"> Mcrypt can operate in four block cipher modes (CBC, OFB, CFB, and ECB). If linked against libmcrypt-2.4.x or higher the functions can also operate in the block cipher mode nOFB and in STREAM mode. Below you find a list with all supported encryption modes together with the constants that are defines for the encryption mode. For a more complete reference and discussion see Applied Cryptography by Schneier (ISBN 0-471-11709-9). <ul class="itemizedlist"> <li class="listitem"> <span class="simpara"> MCRYPT_MODE_ECB (electronic codebook) is suitable for random data, such as encrypting other keys. Since data there is short and random, the disadvantages of ECB have a favorable negative effect. </span> </li> <li class="listitem"> <span class="simpara"> MCRYPT_MODE_CBC (cipher block chaining) is especially suitable for encrypting files where the security is increased over ECB significantly. </span> </li> <li class="listitem"> <span class="simpara"> MCRYPT_MODE_CFB (cipher feedback) is the best mode for encrypting byte streams where single bytes must be encrypted. </span> </li> <li class="listitem"> <span class="simpara"> MCRYPT_MODE_OFB (output feedback, in 8bit) is comparable to CFB, but can be used in applications where error propagation cannot be tolerated. It's insecure (because it operates in 8bit mode) so it is not recommended to use it. </span> </li> <li class="listitem"> <span class="simpara"> MCRYPT_MODE_NOFB (output feedback, in nbit) is comparable to OFB, but more secure because it operates on the block size of the algorithm. </span> </li> <li class="listitem"> <span class="simpara"> MCRYPT_MODE_STREAM is an extra mode to include some stream algorithms like WAKE or RC4. </span> </li> </ul> </p> <p class="para"> Some other mode and random device constants: <dl> <dt> <span class="term"> <b><tt>MCRYPT_ENCRYPT</tt></b> (<a href="language.types.integer.html" class="type integer">integer</a>) </span> <dd> <span class="simpara"> </span> </dd> </dt> <dt> <span class="term"> <b><tt>MCRYPT_DECRYPT</tt></b> (<a href="language.types.integer.html" class="type integer">integer</a>) </span> <dd> <span class="simpara"> </span> </dd> </dt> <dt> <span class="term"> <b><tt>MCRYPT_DEV_RANDOM</tt></b> (<a href="language.types.integer.html" class="type integer">integer</a>) </span> <dd> <span class="simpara"> </span> </dd> </dt> <dt> <span class="term"> <b><tt>MCRYPT_DEV_URANDOM</tt></b> (<a href="language.types.integer.html" class="type integer">integer</a>) </span> <dd> <span class="simpara"> </span> </dd> </dt> <dt> <span class="term"> <b><tt>MCRYPT_RAND</tt></b> (<a href="language.types.integer.html" class="type integer">integer</a>) </span> <dd> <span class="simpara"> </span> </dd> </dt> </dl> </p></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="mcrypt.resources.html">Resource Types</a></div> <div class="next" style="text-align: right; float: right;"><a href="mcrypt.ciphers.html">Mcrypt ciphers</a></div> <div class="up"><a href="book.mcrypt.html">Mcrypt</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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