%PDF-
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Mini Shell
Mini Shell
// Copyright 2015 Joyent, Inc.
module.exports = Signature;
var assert = require('assert-plus');
var Buffer = require('safer-buffer').Buffer;
var algs = require('./algs');
var crypto = require('crypto');
var errs = require('./errors');
var utils = require('./utils');
var asn1 = require('asn1');
var SSHBuffer = require('./ssh-buffer');
var InvalidAlgorithmError = errs.InvalidAlgorithmError;
var SignatureParseError = errs.SignatureParseError;
function Signature(opts) {
assert.object(opts, 'options');
assert.arrayOfObject(opts.parts, 'options.parts');
assert.string(opts.type, 'options.type');
var partLookup = {};
for (var i = 0; i < opts.parts.length; ++i) {
var part = opts.parts[i];
partLookup[part.name] = part;
}
this.type = opts.type;
this.hashAlgorithm = opts.hashAlgo;
this.curve = opts.curve;
this.parts = opts.parts;
this.part = partLookup;
}
Signature.prototype.toBuffer = function (format) {
if (format === undefined)
format = 'asn1';
assert.string(format, 'format');
var buf;
var stype = 'ssh-' + this.type;
switch (this.type) {
case 'rsa':
switch (this.hashAlgorithm) {
case 'sha256':
stype = 'rsa-sha2-256';
break;
case 'sha512':
stype = 'rsa-sha2-512';
break;
case 'sha1':
case undefined:
break;
default:
throw (new Error('SSH signature ' +
'format does not support hash ' +
'algorithm ' + this.hashAlgorithm));
}
if (format === 'ssh') {
buf = new SSHBuffer({});
buf.writeString(stype);
buf.writePart(this.part.sig);
return (buf.toBuffer());
} else {
return (this.part.sig.data);
}
break;
case 'ed25519':
if (format === 'ssh') {
buf = new SSHBuffer({});
buf.writeString(stype);
buf.writePart(this.part.sig);
return (buf.toBuffer());
} else {
return (this.part.sig.data);
}
break;
case 'dsa':
case 'ecdsa':
var r, s;
if (format === 'asn1') {
var der = new asn1.BerWriter();
der.startSequence();
r = utils.mpNormalize(this.part.r.data);
s = utils.mpNormalize(this.part.s.data);
der.writeBuffer(r, asn1.Ber.Integer);
der.writeBuffer(s, asn1.Ber.Integer);
der.endSequence();
return (der.buffer);
} else if (format === 'ssh' && this.type === 'dsa') {
buf = new SSHBuffer({});
buf.writeString('ssh-dss');
r = this.part.r.data;
if (r.length > 20 && r[0] === 0x00)
r = r.slice(1);
s = this.part.s.data;
if (s.length > 20 && s[0] === 0x00)
s = s.slice(1);
if ((this.hashAlgorithm &&
this.hashAlgorithm !== 'sha1') ||
r.length + s.length !== 40) {
throw (new Error('OpenSSH only supports ' +
'DSA signatures with SHA1 hash'));
}
buf.writeBuffer(Buffer.concat([r, s]));
return (buf.toBuffer());
} else if (format === 'ssh' && this.type === 'ecdsa') {
var inner = new SSHBuffer({});
r = this.part.r.data;
inner.writeBuffer(r);
inner.writePart(this.part.s);
buf = new SSHBuffer({});
/* XXX: find a more proper way to do this? */
var curve;
if (r[0] === 0x00)
r = r.slice(1);
var sz = r.length * 8;
if (sz === 256)
curve = 'nistp256';
else if (sz === 384)
curve = 'nistp384';
else if (sz === 528)
curve = 'nistp521';
buf.writeString('ecdsa-sha2-' + curve);
buf.writeBuffer(inner.toBuffer());
return (buf.toBuffer());
}
throw (new Error('Invalid signature format'));
default:
throw (new Error('Invalid signature data'));
}
};
Signature.prototype.toString = function (format) {
assert.optionalString(format, 'format');
return (this.toBuffer(format).toString('base64'));
};
Signature.parse = function (data, type, format) {
if (typeof (data) === 'string')
data = Buffer.from(data, 'base64');
assert.buffer(data, 'data');
assert.string(format, 'format');
assert.string(type, 'type');
var opts = {};
opts.type = type.toLowerCase();
opts.parts = [];
try {
assert.ok(data.length > 0, 'signature must not be empty');
switch (opts.type) {
case 'rsa':
return (parseOneNum(data, type, format, opts));
case 'ed25519':
return (parseOneNum(data, type, format, opts));
case 'dsa':
case 'ecdsa':
if (format === 'asn1')
return (parseDSAasn1(data, type, format, opts));
else if (opts.type === 'dsa')
return (parseDSA(data, type, format, opts));
else
return (parseECDSA(data, type, format, opts));
default:
throw (new InvalidAlgorithmError(type));
}
} catch (e) {
if (e instanceof InvalidAlgorithmError)
throw (e);
throw (new SignatureParseError(type, format, e));
}
};
function parseOneNum(data, type, format, opts) {
if (format === 'ssh') {
try {
var buf = new SSHBuffer({buffer: data});
var head = buf.readString();
} catch (e) {
/* fall through */
}
if (buf !== undefined) {
var msg = 'SSH signature does not match expected ' +
'type (expected ' + type + ', got ' + head + ')';
switch (head) {
case 'ssh-rsa':
assert.strictEqual(type, 'rsa', msg);
opts.hashAlgo = 'sha1';
break;
case 'rsa-sha2-256':
assert.strictEqual(type, 'rsa', msg);
opts.hashAlgo = 'sha256';
break;
case 'rsa-sha2-512':
assert.strictEqual(type, 'rsa', msg);
opts.hashAlgo = 'sha512';
break;
case 'ssh-ed25519':
assert.strictEqual(type, 'ed25519', msg);
opts.hashAlgo = 'sha512';
break;
default:
throw (new Error('Unknown SSH signature ' +
'type: ' + head));
}
var sig = buf.readPart();
assert.ok(buf.atEnd(), 'extra trailing bytes');
sig.name = 'sig';
opts.parts.push(sig);
return (new Signature(opts));
}
}
opts.parts.push({name: 'sig', data: data});
return (new Signature(opts));
}
function parseDSAasn1(data, type, format, opts) {
var der = new asn1.BerReader(data);
der.readSequence();
var r = der.readString(asn1.Ber.Integer, true);
var s = der.readString(asn1.Ber.Integer, true);
opts.parts.push({name: 'r', data: utils.mpNormalize(r)});
opts.parts.push({name: 's', data: utils.mpNormalize(s)});
return (new Signature(opts));
}
function parseDSA(data, type, format, opts) {
if (data.length != 40) {
var buf = new SSHBuffer({buffer: data});
var d = buf.readBuffer();
if (d.toString('ascii') === 'ssh-dss')
d = buf.readBuffer();
assert.ok(buf.atEnd(), 'extra trailing bytes');
assert.strictEqual(d.length, 40, 'invalid inner length');
data = d;
}
opts.parts.push({name: 'r', data: data.slice(0, 20)});
opts.parts.push({name: 's', data: data.slice(20, 40)});
return (new Signature(opts));
}
function parseECDSA(data, type, format, opts) {
var buf = new SSHBuffer({buffer: data});
var r, s;
var inner = buf.readBuffer();
var stype = inner.toString('ascii');
if (stype.slice(0, 6) === 'ecdsa-') {
var parts = stype.split('-');
assert.strictEqual(parts[0], 'ecdsa');
assert.strictEqual(parts[1], 'sha2');
opts.curve = parts[2];
switch (opts.curve) {
case 'nistp256':
opts.hashAlgo = 'sha256';
break;
case 'nistp384':
opts.hashAlgo = 'sha384';
break;
case 'nistp521':
opts.hashAlgo = 'sha512';
break;
default:
throw (new Error('Unsupported ECDSA curve: ' +
opts.curve));
}
inner = buf.readBuffer();
assert.ok(buf.atEnd(), 'extra trailing bytes on outer');
buf = new SSHBuffer({buffer: inner});
r = buf.readPart();
} else {
r = {data: inner};
}
s = buf.readPart();
assert.ok(buf.atEnd(), 'extra trailing bytes');
r.name = 'r';
s.name = 's';
opts.parts.push(r);
opts.parts.push(s);
return (new Signature(opts));
}
Signature.isSignature = function (obj, ver) {
return (utils.isCompatible(obj, Signature, ver));
};
/*
* API versions for Signature:
* [1,0] -- initial ver
* [2,0] -- support for rsa in full ssh format, compat with sshpk-agent
* hashAlgorithm property
* [2,1] -- first tagged version
*/
Signature.prototype._sshpkApiVersion = [2, 1];
Signature._oldVersionDetect = function (obj) {
assert.func(obj.toBuffer);
if (obj.hasOwnProperty('hashAlgorithm'))
return ([2, 0]);
return ([1, 0]);
};
Zerion Mini Shell 1.0