233 lines
6.2 KiB
JavaScript
233 lines
6.2 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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var PEM = require('./pem.js');
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SSH.parse = function (opts) {
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var pub = opts.pem || opts.pub || opts;
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var ssh = SSH.parseBlock(pub);
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if ('OPENSSH PRIVATE KEY' === ssh.type) {
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ssh = SSH.parsePrivateElements(ssh);
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if (7 === ssh.elements.length) {
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// RSA Private Keys have the `e` and `n` swapped (which is actually more normal)
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// but we have to reswap them to make them consistent with the public key format
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ssh.elements.splice(1, 0, ssh.elements.splice(2 ,1)[0]);
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}
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if (opts.public) {
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ssh.elements = ssh.elements.slice(0, 3);
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}
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} else {
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ssh.elements = SSH.parseElements(ssh.bytes);
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}
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//delete ssh.bytes;
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return SSH.parsePublicKey(ssh);
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};
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/*global Promise*/
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SSH.fingerprint = function (opts) {
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var ssh;
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if (opts.bytes) {
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ssh = opts;
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} else {
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ssh = SSH.parseBlock(opts.pub);
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}
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// for browser compat
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return Promise.resolve().then(function () {
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return 'SHA256:' + require('crypto').createHash('sha256')
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.update(ssh.bytes).digest('base64').replace(/=+$/g, '');
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});
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};
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SSH.parseBlock = function (ssh) {
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if (/^-----BEGIN OPENSSH PRIVATE KEY-----/.test(ssh)) {
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return PEM.parseBlock(ssh);
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}
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ssh = ssh.split(/\s+/g);
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return {
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type: ssh[0]
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, bytes: Enc.base64ToBuf(ssh[1])
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, comment: ssh[2]
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};
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};
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SSH.parsePrivateElements = function (ssh) {
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// https://coolaj86.com/articles/the-openssh-private-key-format/
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var buf = ssh.bytes;
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var fulllen = buf.byteLength || buf.length;
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var offset = (buf.byteOffset || 0);
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var dv = new DataView(buf.buffer.slice(offset, offset + fulllen));
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var index = 0;
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var padlen = 0;
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var len;
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var pub;
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// The last byte will be either
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// * a non-printable pad character
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// * a printable comment character
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function lastByteIsPad() {
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var n = ssh.bytes[(ssh.bytes.bytesLength || ssh.bytes.length) - 1];
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return n >= 0x01 && n <= 0x07;
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}
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while (lastByteIsPad()) {
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padlen += 1;
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len = (ssh.bytes.bytesLength || ssh.bytes.length);
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ssh.bytes = ssh.bytes.slice(0, len - 1);
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}
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// o p e n s s h - k e y - v 1 NULL
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// 6f 70 65 6e 73 73 68 2d 6b 65 79 2d 76 31 00
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// 15 characters
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// 4-byte len, "none" (encryption)
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// 4-byte len, "none" (kdfname)
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if ('none' !== Enc.bufToBin(ssh.bytes.slice(15 + 8 + 4, 15 + 8 + 8))) {
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throw new Error("Key is either encrypted (not yet supported), corrupt, or not openssh-key-v1");
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}
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if (padlen >= 8) {
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throw new Error("Padding length should be between 0 and 7, not '" + padlen + "'."
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+ " Probably not an ssh private key.");
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}
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// 4-byte len, nil (kdf)
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// 4-byte number of keys
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index += 15 + 8 + 8 + 4 + 4;
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// length of public key
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len = dv.getUint32(index, false);
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// throw away public key (it's in the private key)
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index += 4 + len;
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pub = ssh.bytes.slice(index - len, index);
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// length of dummy checksum + private key + padding
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len = dv.getUint32(index, false) - padlen;
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// throw away dummy checksum
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index += 4 + 8;
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ssh.elements = SSH.parseElements(ssh.bytes.slice(index, index + (len - 8)));
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index += Array.prototype.reduce.call(ssh.elements, function (el, sum) {
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// 32-bit len + element len
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return 4 + (el.byteLength || el.length) + sum;
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}, 0);
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// comment will exist, even if it's an empty string
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ssh.comment = Enc.bufToBin(ssh.elements.pop());
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ssh.bytes = pub;
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return ssh;
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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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// Note: node has weird offsets
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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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if (0 === len) { continue; }
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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("invalid ssh public key length \n" + els.map(function (b) {
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return Enc.bufToHex(b);
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}).join('\n'));
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}
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return els;
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};
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SSH.parsePublicKey = function (ssh) {
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var els = ssh.elements;
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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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if (3 === els.length) {
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ssh.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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} else {
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console.log('len:', els.length);
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ssh.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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, d: Enc.bufToUrlBase64(els[3])
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, p: Enc.bufToUrlBase64(els[5])
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, q: Enc.bufToUrlBase64(els[6])
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//, dp: Enc.bufToUrlBase64(els[x])
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//, dq: Enc.bufToUrlBase64(els[x])
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, qi: Enc.bufToUrlBase64(els[4])
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};
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}
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return ssh;
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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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ssh.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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ssh.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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var d;
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// I don't think EC keys use 0x00 padding, but just in case
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while (0x00 === x[0]) { x = x.slice(1); }
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while (0x00 === y[0]) { y = y.slice(1); }
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if (els[3]) {
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d = els[3];
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while (0x00 === d[0]) { d = d.slice(1); }
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ssh.jwk.d = Enc.bufToUrlBase64(d);
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}
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ssh.jwk.x = Enc.bufToUrlBase64(x);
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ssh.jwk.y = Enc.bufToUrlBase64(y);
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return ssh;
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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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