// Copyright 2015 Joyent, Inc.
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module.exports = Signature;
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var assert = require('assert-plus');
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var Buffer = require('safer-buffer').Buffer;
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var algs = require('./algs');
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var crypto = require('crypto');
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var errs = require('./errors');
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var utils = require('./utils');
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var asn1 = require('asn1');
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var SSHBuffer = require('./ssh-buffer');
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var InvalidAlgorithmError = errs.InvalidAlgorithmError;
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var SignatureParseError = errs.SignatureParseError;
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function Signature(opts) {
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assert.object(opts, 'options');
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assert.arrayOfObject(opts.parts, 'options.parts');
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assert.string(opts.type, 'options.type');
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var partLookup = {};
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for (var i = 0; i < opts.parts.length; ++i) {
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var part = opts.parts[i];
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partLookup[part.name] = part;
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}
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this.type = opts.type;
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this.hashAlgorithm = opts.hashAlgo;
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this.curve = opts.curve;
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this.parts = opts.parts;
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this.part = partLookup;
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}
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Signature.prototype.toBuffer = function (format) {
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if (format === undefined)
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format = 'asn1';
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assert.string(format, 'format');
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var buf;
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var stype = 'ssh-' + this.type;
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switch (this.type) {
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case 'rsa':
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switch (this.hashAlgorithm) {
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case 'sha256':
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stype = 'rsa-sha2-256';
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break;
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case 'sha512':
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stype = 'rsa-sha2-512';
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break;
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case 'sha1':
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case undefined:
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break;
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default:
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throw (new Error('SSH signature ' +
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'format does not support hash ' +
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'algorithm ' + this.hashAlgorithm));
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}
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if (format === 'ssh') {
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buf = new SSHBuffer({});
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buf.writeString(stype);
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buf.writePart(this.part.sig);
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return (buf.toBuffer());
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} else {
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return (this.part.sig.data);
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}
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break;
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case 'ed25519':
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if (format === 'ssh') {
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buf = new SSHBuffer({});
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buf.writeString(stype);
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buf.writePart(this.part.sig);
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return (buf.toBuffer());
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} else {
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return (this.part.sig.data);
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}
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break;
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case 'dsa':
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case 'ecdsa':
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var r, s;
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if (format === 'asn1') {
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var der = new asn1.BerWriter();
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der.startSequence();
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r = utils.mpNormalize(this.part.r.data);
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s = utils.mpNormalize(this.part.s.data);
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der.writeBuffer(r, asn1.Ber.Integer);
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der.writeBuffer(s, asn1.Ber.Integer);
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der.endSequence();
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return (der.buffer);
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} else if (format === 'ssh' && this.type === 'dsa') {
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buf = new SSHBuffer({});
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buf.writeString('ssh-dss');
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r = this.part.r.data;
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if (r.length > 20 && r[0] === 0x00)
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r = r.slice(1);
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s = this.part.s.data;
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if (s.length > 20 && s[0] === 0x00)
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s = s.slice(1);
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if ((this.hashAlgorithm &&
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this.hashAlgorithm !== 'sha1') ||
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r.length + s.length !== 40) {
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throw (new Error('OpenSSH only supports ' +
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'DSA signatures with SHA1 hash'));
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}
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buf.writeBuffer(Buffer.concat([r, s]));
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return (buf.toBuffer());
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} else if (format === 'ssh' && this.type === 'ecdsa') {
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var inner = new SSHBuffer({});
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r = this.part.r.data;
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inner.writeBuffer(r);
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inner.writePart(this.part.s);
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buf = new SSHBuffer({});
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/* XXX: find a more proper way to do this? */
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var curve;
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if (r[0] === 0x00)
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r = r.slice(1);
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var sz = r.length * 8;
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if (sz === 256)
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curve = 'nistp256';
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else if (sz === 384)
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curve = 'nistp384';
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else if (sz === 528)
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curve = 'nistp521';
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buf.writeString('ecdsa-sha2-' + curve);
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buf.writeBuffer(inner.toBuffer());
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return (buf.toBuffer());
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}
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throw (new Error('Invalid signature format'));
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default:
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throw (new Error('Invalid signature data'));
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}
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};
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Signature.prototype.toString = function (format) {
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assert.optionalString(format, 'format');
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return (this.toBuffer(format).toString('base64'));
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};
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Signature.parse = function (data, type, format) {
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if (typeof (data) === 'string')
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data = Buffer.from(data, 'base64');
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assert.buffer(data, 'data');
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assert.string(format, 'format');
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assert.string(type, 'type');
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var opts = {};
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opts.type = type.toLowerCase();
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opts.parts = [];
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try {
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assert.ok(data.length > 0, 'signature must not be empty');
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switch (opts.type) {
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case 'rsa':
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return (parseOneNum(data, type, format, opts));
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case 'ed25519':
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return (parseOneNum(data, type, format, opts));
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case 'dsa':
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case 'ecdsa':
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if (format === 'asn1')
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return (parseDSAasn1(data, type, format, opts));
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else if (opts.type === 'dsa')
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return (parseDSA(data, type, format, opts));
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else
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return (parseECDSA(data, type, format, opts));
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default:
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throw (new InvalidAlgorithmError(type));
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}
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} catch (e) {
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if (e instanceof InvalidAlgorithmError)
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throw (e);
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throw (new SignatureParseError(type, format, e));
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}
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};
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function parseOneNum(data, type, format, opts) {
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if (format === 'ssh') {
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try {
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var buf = new SSHBuffer({buffer: data});
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var head = buf.readString();
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} catch (e) {
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/* fall through */
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}
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if (buf !== undefined) {
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var msg = 'SSH signature does not match expected ' +
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'type (expected ' + type + ', got ' + head + ')';
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switch (head) {
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case 'ssh-rsa':
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assert.strictEqual(type, 'rsa', msg);
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opts.hashAlgo = 'sha1';
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break;
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case 'rsa-sha2-256':
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assert.strictEqual(type, 'rsa', msg);
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opts.hashAlgo = 'sha256';
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break;
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case 'rsa-sha2-512':
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assert.strictEqual(type, 'rsa', msg);
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opts.hashAlgo = 'sha512';
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break;
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case 'ssh-ed25519':
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assert.strictEqual(type, 'ed25519', msg);
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opts.hashAlgo = 'sha512';
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break;
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default:
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throw (new Error('Unknown SSH signature ' +
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'type: ' + head));
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}
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var sig = buf.readPart();
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assert.ok(buf.atEnd(), 'extra trailing bytes');
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sig.name = 'sig';
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opts.parts.push(sig);
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return (new Signature(opts));
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}
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}
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opts.parts.push({name: 'sig', data: data});
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return (new Signature(opts));
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}
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function parseDSAasn1(data, type, format, opts) {
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var der = new asn1.BerReader(data);
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der.readSequence();
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var r = der.readString(asn1.Ber.Integer, true);
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var s = der.readString(asn1.Ber.Integer, true);
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opts.parts.push({name: 'r', data: utils.mpNormalize(r)});
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opts.parts.push({name: 's', data: utils.mpNormalize(s)});
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return (new Signature(opts));
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}
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function parseDSA(data, type, format, opts) {
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if (data.length != 40) {
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var buf = new SSHBuffer({buffer: data});
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var d = buf.readBuffer();
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if (d.toString('ascii') === 'ssh-dss')
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d = buf.readBuffer();
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assert.ok(buf.atEnd(), 'extra trailing bytes');
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assert.strictEqual(d.length, 40, 'invalid inner length');
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data = d;
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}
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opts.parts.push({name: 'r', data: data.slice(0, 20)});
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opts.parts.push({name: 's', data: data.slice(20, 40)});
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return (new Signature(opts));
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}
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function parseECDSA(data, type, format, opts) {
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var buf = new SSHBuffer({buffer: data});
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var r, s;
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var inner = buf.readBuffer();
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var stype = inner.toString('ascii');
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if (stype.slice(0, 6) === 'ecdsa-') {
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var parts = stype.split('-');
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assert.strictEqual(parts[0], 'ecdsa');
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assert.strictEqual(parts[1], 'sha2');
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opts.curve = parts[2];
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switch (opts.curve) {
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case 'nistp256':
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opts.hashAlgo = 'sha256';
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break;
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case 'nistp384':
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opts.hashAlgo = 'sha384';
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break;
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case 'nistp521':
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opts.hashAlgo = 'sha512';
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break;
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default:
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throw (new Error('Unsupported ECDSA curve: ' +
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opts.curve));
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}
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inner = buf.readBuffer();
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assert.ok(buf.atEnd(), 'extra trailing bytes on outer');
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buf = new SSHBuffer({buffer: inner});
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r = buf.readPart();
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} else {
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r = {data: inner};
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}
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s = buf.readPart();
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assert.ok(buf.atEnd(), 'extra trailing bytes');
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r.name = 'r';
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s.name = 's';
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opts.parts.push(r);
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opts.parts.push(s);
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return (new Signature(opts));
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}
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Signature.isSignature = function (obj, ver) {
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return (utils.isCompatible(obj, Signature, ver));
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};
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/*
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* API versions for Signature:
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* [1,0] -- initial ver
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* [2,0] -- support for rsa in full ssh format, compat with sshpk-agent
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* hashAlgorithm property
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* [2,1] -- first tagged version
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*/
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Signature.prototype._sshpkApiVersion = [2, 1];
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Signature._oldVersionDetect = function (obj) {
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assert.func(obj.toBuffer);
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if (obj.hasOwnProperty('hashAlgorithm'))
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return ([2, 0]);
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return ([1, 0]);
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};
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