@@ -91,7 +91,6 @@ module.exports = {
91 91
result += message;
92 92
return result;
93 93
},
94 - 95 94
/**
96 95
* decodes a EME-PKCS1-v1_5 padding (See {@link http://tools.ietf.org/html/rfc4880#section-13.1.2|RFC 4880 13.1.2})
97 96
* @param {String} message EME-PKCS1 padded message
@@ -110,53 +109,47 @@ module.exports = {
110 109
},
111 110 112 111
emsa: {
113 - 114 112
/**
115 113
* create a EMSA-PKCS1-v1_5 padding (See {@link http://tools.ietf.org/html/rfc4880#section-13.1.3|RFC 4880 13.1.3})
116 114
* @param {Integer} algo Hash algorithm type used
117 -
* @param {String} data Data to be hashed
118 -
* @param {Integer} keylength Key size of the public mpi in bytes
119 -
* @returns {String} Hashcode with pkcs1padding as string
115 +
* @param {String} M message to be encoded
116 +
* @param {Integer} emLen intended length in octets of the encoded message
117 +
* @returns {String} encoded message
120 118
*/
121 -
encode: function(algo, data, keylength) {
122 -
var data2 = "";
123 -
data2 += String.fromCharCode(0x00);
124 -
data2 += String.fromCharCode(0x01);
119 +
encode: function(algo, M, emLen) {
125 120
var i;
126 -
for (i = 0; i < (keylength - hash_headers[algo].length - 3 -
127 -
hash.getHashByteLength(algo)); i++)
128 - 129 -
data2 += String.fromCharCode(0xff);
130 - 131 -
data2 += String.fromCharCode(0x00);
132 - 133 -
for (i = 0; i < hash_headers[algo].length; i++)
134 -
data2 += String.fromCharCode(hash_headers[algo][i]);
135 - 136 -
data2 += hash.digest(algo, data);
137 -
return new BigInteger(util.hexstrdump(data2), 16);
138 -
},
139 - 140 -
/**
141 -
* extract the hash out of an EMSA-PKCS1-v1.5 padding (See {@link http://tools.ietf.org/html/rfc4880#section-13.1.3|RFC 4880 13.1.3})
142 -
* @param {String} data Hash in pkcs1 encoding
143 -
* @returns {String} The hash as string
144 -
*/
145 -
decode: function(algo, data) {
146 -
var i = 0;
147 -
if (data.charCodeAt(0) === 0) i++;
148 -
else if (data.charCodeAt(0) != 1) return -1;
149 -
else i++;
150 - 151 -
while (data.charCodeAt(i) == 0xFF) i++;
152 -
if (data.charCodeAt(i++) !== 0) return -1;
153 -
var j = 0;
154 -
for (j = 0; j < hash_headers[algo].length && j + i < data.length; j++) {
155 -
if (data.charCodeAt(j + i) != hash_headers[algo][j]) return -1;
121 +
// Apply the hash function to the message M to produce a hash value H
122 +
var H = hash.digest(algo, M);
123 +
if (H.length !== hash.getHashByteLength(algo)) {
124 +
throw new Error('Invalid hash length');
125 +
}
126 +
// produce an ASN.1 DER value for the hash function used.
127 +
// Let T be the full hash prefix
128 +
var T = '';
129 +
for (i = 0; i < hash_headers[algo].length; i++) {
130 +
T += String.fromCharCode(hash_headers[algo][i]);
131 +
}
132 +
// add hash value to prefix
133 +
T += H;
134 +
// and let tLen be the length in octets of T
135 +
var tLen = T.length;
136 +
if (emLen < tLen + 11) {
137 +
throw new Error('Intended encoded message length too short');
138 +
}
139 +
// an octet string PS consisting of emLen - tLen - 3 octets with hexadecimal value 0xFF
140 +
// The length of PS will be at least 8 octets
141 +
var PS = '';
142 +
for (i = 0; i < (emLen - tLen - 3); i++) {
143 +
PS += String.fromCharCode(0xff);
156 144
}
157 -
i += j;
158 -
if (data.substring(i).length < hash.getHashByteLength(algo)) return -1;
159 -
return data.substring(i);
145 +
// Concatenate PS, the hash prefix T, and other padding to form the
146 +
// encoded message EM as EM = 0x00 || 0x01 || PS || 0x00 || T.
147 +
var EM = String.fromCharCode(0x00) +
148 +
String.fromCharCode(0x01) +
149 +
PS +
150 +
String.fromCharCode(0x00) +
151 +
T;
152 +
return new BigInteger(util.hexstrdump(EM), 16);
160 153
}
161 154
}
162 155
};
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