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<h1 class="page-title">Source: packet/openpgp.packet.modificationdetectioncode.js</h1>
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<pre class="prettyprint source"><code>// GPG4Browsers - An OpenPGP implementation in javascript
// Copyright (C) 2011 Recurity Labs GmbH
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
/**
* @class
* @classdesc Implementation of the Modification Detection Code Packet (Tag 19)
*
* RFC4880 5.14: The Modification Detection Code packet contains a SHA-1 hash of
* plaintext data, which is used to detect message modification. It is only used
* with a Symmetrically Encrypted Integrity Protected Data packet. The
* Modification Detection Code packet MUST be the last packet in the plaintext
* data that is encrypted in the Symmetrically Encrypted Integrity Protected
* Data packet, and MUST appear in no other place.
*/
function openpgp_packet_modificationdetectioncode() {
this.tagType = 19;
this.hash = null;
/**
* parsing function for a modification detection code packet (tag 19).
*
* @param {String} input payload of a tag 19 packet
* @param {Integer} position
* position to start reading from the input string
* @param {Integer} len
* length of the packet or the remaining length of
* input at position
* @return {openpgp_packet_encrypteddata} object representation
*/
function read_packet(input, position, len) {
this.packetLength = len;
if (len != 20) {
util
.print_error("openpgp.packet.modificationdetectioncode.js\n"
+ 'invalid length for a modification detection code packet!'
+ len);
return null;
}
// - A 20-octet SHA-1 hash of the preceding plaintext data of the
// Symmetrically Encrypted Integrity Protected Data packet,
// including prefix data, the tag octet, and length octet of the
// Modification Detection Code packet.
this.hash = input.substring(position, position + 20);
return this;
}
/*
* this packet is created within the encryptedintegrityprotected packet
* function write_packet(data) { }
*/
/**
* generates debug output (pretty print)
*
* @return {String} String which gives some information about the
* modification detection code
*/
function toString() {
return '5.14 Modification detection code packet\n' + ' bytes ('
+ this.hash.length + '): [' + util.hexstrdump(this.hash) + ']';
}
this.read_packet = read_packet;
this.toString = toString;
};
</code></pre>
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Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.2.0-dev</a> on Tue Apr 16 2013 10:42:39 GMT+0200 (CEST)
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