/**
* Javascript implementation of basic PEM (Privacy Enhanced Mail) algorithms.
*
* See: RFC 1421.
*
* @author Dave Longley
*
* Copyright (c) 2013-2014 Digital Bazaar, Inc.
*
* A Forge PEM object has the following fields:
*
* type: identifies the type of message (eg: "RSA PRIVATE KEY").
*
* procType: identifies the type of processing performed on the message,
* it has two subfields: version and type, eg: 4,ENCRYPTED.
*
* contentDomain: identifies the type of content in the message, typically
* only uses the value: "RFC822".
*
* dekInfo: identifies the message encryption algorithm and mode and includes
* any parameters for the algorithm, it has two subfields: algorithm and
* parameters, eg: DES-CBC,F8143EDE5960C597.
*
* headers: contains all other PEM encapsulated headers -- where order is
* significant (for pairing data like recipient ID + key info).
*
* body: the binary-encoded body.
*/
var forge = require('./forge');
require('./util');
// shortcut for pem API
var pem = module.exports = forge.pem = forge.pem || {};
/**
* Encodes (serializes) the given PEM object.
*
* @param msg the PEM message object to encode.
* @param options the options to use:
* maxline the maximum characters per line for the body, (default: 64).
*
* @return the PEM-formatted string.
*/
pem.encode = function(msg, options) {
options = options || {};
var rval = '-----BEGIN ' + msg.type + '-----\r\n';
// encode special headers
var header;
if(msg.procType) {
header = {
name: 'Proc-Type',
values: [String(msg.procType.version), msg.procType.type]
};
rval += foldHeader(header);
}
if(msg.contentDomain) {
header = {name: 'Content-Domain', values: [msg.contentDomain]};
rval += foldHeader(header);
}
if(msg.dekInfo) {
header = {name: 'DEK-Info', values: [msg.dekInfo.algorithm]};
if(msg.dekInfo.parameters) {
header.values.push(msg.dekInfo.parameters);
}
rval += foldHeader(header);
}
if(msg.headers) {
// encode all other headers
for(var i = 0; i < msg.headers.length; ++i) {
rval += foldHeader(msg.headers[i]);
}
}
// terminate header
if(msg.procType) {
rval += '\r\n';
}
// add body
rval += forge.util.encode64(msg.body, options.maxline || 64) + '\r\n';
rval += '-----END ' + msg.type + '-----\r\n';
return rval;
};
/**
* Decodes (deserializes) all PEM messages found in the given string.
*
* @param str the PEM-formatted string to decode.
*
* @return the PEM message objects in an array.
*/
pem.decode = function(str) {
var rval = [];
// split string into PEM messages (be lenient w/EOF on BEGIN line)
var rMessage = /\s*-----BEGIN ([A-Z0-9- ]+)-----\r?\n?([\x21-\x7e\s]+?(?:\r?\n\r?\n))?([:A-Za-z0-9+\/=\s]+?)-----END \1-----/g;
var rHeader = /([\x21-\x7e]+):\s*([\x21-\x7e\s^:]+)/;
var rCRLF = /\r?\n/;
var match;
while(true) {
match = rMessage.exec(str);
if(!match) {
break;
}
var msg = {
type: match[1],
procType: null,
contentDomain: null,
dekInfo: null,
headers: [],
body: forge.util.decode64(match[3])
};
rval.push(msg);
// no headers
if(!match[2]) {
continue;
}
// parse headers
var lines = match[2].split(rCRLF);
var li = 0;
while(match && li < lines.length) {
// get line, trim any rhs whitespace
var line = lines[li].replace(/\s+$/, '');
// RFC2822 unfold any following folded lines
for(var nl = li + 1; nl < lines.length; ++nl) {
var next = lines[nl];
if(!/\s/.test(next[0])) {
break;
}
line += next;
li = nl;
}
// parse header
match = line.match(rHeader);
if(match) {
var header = {name: match[1], values: []};
var values = match[2].split(',');
for(var vi = 0; vi < values.length; ++vi) {
header.values.push(ltrim(values[vi]));
}
// Proc-Type must be the first header
if(!msg.procType) {
if(header.name !== 'Proc-Type') {
throw new Error('Invalid PEM formatted message. The first ' +
'encapsulated header must be "Proc-Type".');
} else if(header.values.length !== 2) {
throw new Error('Invalid PEM formatted message. The "Proc-Type" ' +
'header must have two subfields.');
}
msg.procType = {version: values[0], type: values[1]};
} else if(!msg.contentDomain && header.name === 'Content-Domain') {
// special-case Content-Domain
msg.contentDomain = values[0] || '';
} else if(!msg.dekInfo && header.name === 'DEK-Info') {
// special-case DEK-Info
if(header.values.length === 0) {
throw new Error('Invalid PEM formatted message. The "DEK-Info" ' +
'header must have at least one subfield.');
}
msg.dekInfo = {algorithm: values[0], parameters: values[1] || null};
} else {
msg.headers.push(header);
}
}
++li;
}
if(msg.procType === 'ENCRYPTED' && !msg.dekInfo) {
throw new Error('Invalid PEM formatted message. The "DEK-Info" ' +
'header must be present if "Proc-Type" is "ENCRYPTED".');
}
}
if(rval.length === 0) {
throw new Error('Invalid PEM formatted message.');
}
return rval;
};
function foldHeader(header) {
var rval = header.name + ': ';
// ensure values with CRLF are folded
var values = [];
var insertSpace = function(match, $1) {
return ' ' + $1;
};
for(var i = 0; i < header.values.length; ++i) {
values.push(header.values[i].replace(/^(\S+\r\n)/, insertSpace));
}
rval += values.join(',') + '\r\n';
// do folding
var length = 0;
var candidate = -1;
for(var i = 0; i < rval.length; ++i, ++length) {
if(length > 65 && candidate !== -1) {
var insert = rval[candidate];
if(insert === ',') {
++candidate;
rval = rval.substr(0, candidate) + '\r\n ' + rval.substr(candidate);
} else {
rval = rval.substr(0, candidate) +
'\r\n' + insert + rval.substr(candidate + 1);
}
length = (i - candidate - 1);
candidate = -1;
++i;
} else if(rval[i] === ' ' || rval[i] === '\t' || rval[i] === ',') {
candidate = i;
}
}
return rval;
}
function ltrim(str) {
return str.replace(/^\s+/, '');
}
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