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105 lines
2.6 KiB
105 lines
2.6 KiB
import parseKeys from "../parse-asn1";
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import mgf from "./mgf";
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import xor from "./xor";
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import BN from "../bn.js";
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import crt from "../browserify-rsa";
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import createHash from "../create-hash";
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import withPublic from "./withPublic";
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function oaep(key, msg) {
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var k = key.modulus.byteLength();
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var iHash = createHash('sha1').update(Buffer.alloc(0)).digest();
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var hLen = iHash.length;
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if (msg[0] !== 0) {
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throw new Error('decryption error');
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}
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var maskedSeed = msg.slice(1, hLen + 1);
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var maskedDb = msg.slice(hLen + 1);
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var seed = xor(maskedSeed, mgf(maskedDb, hLen));
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var db = xor(maskedDb, mgf(seed, k - hLen - 1));
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if (compare(iHash, db.slice(0, hLen))) {
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throw new Error('decryption error');
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}
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var i = hLen;
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while (db[i] === 0) {
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i++;
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}
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if (db[i++] !== 1) {
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throw new Error('decryption error');
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}
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return db.slice(i);
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}
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function pkcs1(key, msg, reverse) {
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var p1 = msg.slice(0, 2);
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var i = 2;
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var status = 0;
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while (msg[i++] !== 0) {
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if (i >= msg.length) {
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status++;
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break;
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}
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}
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var ps = msg.slice(2, i - 1);
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if ((p1.toString('hex') !== '0002' && !reverse) || (p1.toString('hex') !== '0001' && reverse)) {
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status++;
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}
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if (ps.length < 8) {
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status++;
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}
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if (status) {
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throw new Error('decryption error');
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}
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return msg.slice(i);
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}
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function compare(a, b) {
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a = Buffer.from(a);
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b = Buffer.from(b);
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var dif = 0;
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var len = a.length;
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if (a.length !== b.length) {
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dif++;
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len = Math.min(a.length, b.length);
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}
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var i = -1;
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while (++i < len) {
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dif += (a[i] ^ b[i]);
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}
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return dif;
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}
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export default (function privateDecrypt(privateKey, enc, reverse) {
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var padding;
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if (privateKey.padding) {
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padding = privateKey.padding;
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}
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else if (reverse) {
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padding = 1;
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}
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else {
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padding = 4;
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}
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var key = parseKeys(privateKey);
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var k = key.modulus.byteLength();
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if (enc.length > k || new BN(enc).cmp(key.modulus) >= 0) {
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throw new Error('decryption error');
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}
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var msg;
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if (reverse) {
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msg = withPublic(new BN(enc), key);
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}
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else {
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msg = crt(enc, key);
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}
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var zBuffer = Buffer.alloc(k - msg.length);
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msg = Buffer.concat([zBuffer, msg], k);
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if (padding === 4) {
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return oaep(key, msg);
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}
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else if (padding === 1) {
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return pkcs1(key, msg, reverse);
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}
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else if (padding === 3) {
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return msg;
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}
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else {
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throw new Error('unknown padding');
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}
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});
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