102 lines
2.4 KiB
JavaScript
102 lines
2.4 KiB
JavaScript
'use strict';
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var SSH = module.exports;
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var Enc = require('./encoding.js');
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SSH.parse = function (ssh) {
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ssh = ssh.split(/\s+/g);
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var result = { type: ssh[0], jwk: null, comment: ssh[2] || '' };
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var buf = Enc.base64ToBuf(ssh[1]);
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var els = SSH.parseElements(buf);
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var typ = Enc.bufToBin(els[0]);
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var len;
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// RSA keys are all the same
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if (SSH.types.rsa === typ) {
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result.jwk = {
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kty: 'RSA'
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, n: Enc.bufToUrlBase64(els[2])
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, e: Enc.bufToUrlBase64(els[1])
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};
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return result;
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}
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// EC keys are each different
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if (SSH.types.p256 === typ) {
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len = 32;
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result.jwk = { kty: 'EC', crv: 'P-256' };
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} else if (SSH.types.p384 === typ) {
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len = 48;
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result.jwk = { kty: 'EC', crv: 'P-384' };
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} else {
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throw new Error("Unsupported ssh public key type: "
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+ Enc.bufToBin(els[0]));
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}
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// els[1] is just a repeat of a subset of els[0]
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var x = els[2].slice(1, 1 + len);
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var y = els[2].slice(1 + len, 1 + len + len);
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// I don't think EC keys use 0x00 padding, but just in case
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if (0x00 === x[0]) { x = x.slice(1); }
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if (0x00 === y[0]) { y = y.slice(1); }
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result.jwk.x = Enc.bufToUrlBase64(x);
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result.jwk.y = Enc.bufToUrlBase64(y);
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return result;
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};
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SSH.parseElements = function (buf) {
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var fulllen = buf.byteLength || buf.length;
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var offset = (buf.byteOffset || 0);
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var i = 0;
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var index = 0;
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// using dataview to be browser-compatible (I do want _some_ code reuse)
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var dv = new DataView(buf.buffer.slice(offset, offset + fulllen));
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var els = [];
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var el;
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var len;
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while (index < fulllen) {
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i += 1;
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if (i > 15) { throw new Error("15+ elements, probably not a public ssh key"); }
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len = dv.getUint32(index, false);
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index += 4;
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el = buf.slice(index, index + len);
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// remove BigUInt '00' prefix
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if (0x00 === el[0]) {
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el = el.slice(1);
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}
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els.push(el);
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index += len;
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}
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if (fulllen !== index) {
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throw new Error(els.map(function (b) {
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return Enc.bufToHex(b);
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}).join('\n') + "invalid ssh public key length");
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}
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return els;
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};
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SSH.types = {
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// 19 '00000013'
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// e c d s a - s h a 2 - n i s t p 2 5 6
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// 65636473612d736861322d6e69737470323536
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// 6e69737470323536
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p256: 'ecdsa-sha2-nistp256'
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// 19 '00000013'
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// e c d s a - s h a 2 - n i s t p 3 8 4
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// 65636473612d736861322d6e69737470333834
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// 6e69737470323536
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, p384: 'ecdsa-sha2-nistp384'
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// 7 '00000007'
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// s s h - r s a
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// 7373682d727361
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, rsa: 'ssh-rsa'
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};
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