1 | // Copyright 2017 Joyent, Inc.
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2 |
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3 | module.exports = {
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4 | read: read,
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5 | verify: verify,
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6 | sign: sign,
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7 | signAsync: signAsync,
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8 | write: write,
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9 |
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10 | /* Internal private API */
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11 | fromBuffer: fromBuffer,
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12 | toBuffer: toBuffer
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13 | };
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14 |
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15 | var assert = require('assert-plus');
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16 | var SSHBuffer = require('../ssh-buffer');
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17 | var crypto = require('crypto');
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18 | var Buffer = require('safer-buffer').Buffer;
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19 | var algs = require('../algs');
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20 | var Key = require('../key');
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21 | var PrivateKey = require('../private-key');
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22 | var Identity = require('../identity');
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23 | var rfc4253 = require('./rfc4253');
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24 | var Signature = require('../signature');
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25 | var utils = require('../utils');
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26 | var Certificate = require('../certificate');
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27 |
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28 | function verify(cert, key) {
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29 | /*
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30 | * We always give an issuerKey, so if our verify() is being called then
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31 | * there was no signature. Return false.
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32 | */
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33 | return (false);
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34 | }
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35 |
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36 | var TYPES = {
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37 | 'user': 1,
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38 | 'host': 2
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39 | };
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40 | Object.keys(TYPES).forEach(function (k) { TYPES[TYPES[k]] = k; });
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41 |
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42 | var ECDSA_ALGO = /^ecdsa-sha2-([^@-]+)-cert-v01@openssh.com$/;
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43 |
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44 | function read(buf, options) {
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45 | if (Buffer.isBuffer(buf))
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46 | buf = buf.toString('ascii');
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47 | var parts = buf.trim().split(/[ \t\n]+/g);
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48 | if (parts.length < 2 || parts.length > 3)
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49 | throw (new Error('Not a valid SSH certificate line'));
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50 |
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51 | var algo = parts[0];
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52 | var data = parts[1];
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53 |
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54 | data = Buffer.from(data, 'base64');
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55 | return (fromBuffer(data, algo));
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56 | }
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57 |
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58 | function fromBuffer(data, algo, partial) {
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59 | var sshbuf = new SSHBuffer({ buffer: data });
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60 | var innerAlgo = sshbuf.readString();
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61 | if (algo !== undefined && innerAlgo !== algo)
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62 | throw (new Error('SSH certificate algorithm mismatch'));
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63 | if (algo === undefined)
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64 | algo = innerAlgo;
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65 |
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66 | var cert = {};
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67 | cert.signatures = {};
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68 | cert.signatures.openssh = {};
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69 |
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70 | cert.signatures.openssh.nonce = sshbuf.readBuffer();
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71 |
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72 | var key = {};
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73 | var parts = (key.parts = []);
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74 | key.type = getAlg(algo);
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75 |
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76 | var partCount = algs.info[key.type].parts.length;
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77 | while (parts.length < partCount)
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78 | parts.push(sshbuf.readPart());
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79 | assert.ok(parts.length >= 1, 'key must have at least one part');
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80 |
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81 | var algInfo = algs.info[key.type];
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82 | if (key.type === 'ecdsa') {
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83 | var res = ECDSA_ALGO.exec(algo);
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84 | assert.ok(res !== null);
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85 | assert.strictEqual(res[1], parts[0].data.toString());
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86 | }
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87 |
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88 | for (var i = 0; i < algInfo.parts.length; ++i) {
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89 | parts[i].name = algInfo.parts[i];
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90 | if (parts[i].name !== 'curve' &&
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91 | algInfo.normalize !== false) {
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92 | var p = parts[i];
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93 | p.data = utils.mpNormalize(p.data);
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94 | }
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95 | }
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96 |
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97 | cert.subjectKey = new Key(key);
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98 |
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99 | cert.serial = sshbuf.readInt64();
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100 |
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101 | var type = TYPES[sshbuf.readInt()];
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102 | assert.string(type, 'valid cert type');
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103 |
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104 | cert.signatures.openssh.keyId = sshbuf.readString();
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105 |
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106 | var principals = [];
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107 | var pbuf = sshbuf.readBuffer();
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108 | var psshbuf = new SSHBuffer({ buffer: pbuf });
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109 | while (!psshbuf.atEnd())
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110 | principals.push(psshbuf.readString());
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111 | if (principals.length === 0)
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112 | principals = ['*'];
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113 |
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114 | cert.subjects = principals.map(function (pr) {
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115 | if (type === 'user')
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116 | return (Identity.forUser(pr));
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117 | else if (type === 'host')
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118 | return (Identity.forHost(pr));
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119 | throw (new Error('Unknown identity type ' + type));
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120 | });
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121 |
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122 | cert.validFrom = int64ToDate(sshbuf.readInt64());
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123 | cert.validUntil = int64ToDate(sshbuf.readInt64());
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124 |
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125 | var exts = [];
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126 | var extbuf = new SSHBuffer({ buffer: sshbuf.readBuffer() });
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127 | var ext;
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128 | while (!extbuf.atEnd()) {
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129 | ext = { critical: true };
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130 | ext.name = extbuf.readString();
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131 | ext.data = extbuf.readBuffer();
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132 | exts.push(ext);
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133 | }
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134 | extbuf = new SSHBuffer({ buffer: sshbuf.readBuffer() });
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135 | while (!extbuf.atEnd()) {
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136 | ext = { critical: false };
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137 | ext.name = extbuf.readString();
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138 | ext.data = extbuf.readBuffer();
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139 | exts.push(ext);
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140 | }
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141 | cert.signatures.openssh.exts = exts;
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142 |
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143 | /* reserved */
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144 | sshbuf.readBuffer();
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145 |
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146 | var signingKeyBuf = sshbuf.readBuffer();
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147 | cert.issuerKey = rfc4253.read(signingKeyBuf);
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148 |
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149 | /*
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150 | * OpenSSH certs don't give the identity of the issuer, just their
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151 | * public key. So, we use an Identity that matches anything. The
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152 | * isSignedBy() function will later tell you if the key matches.
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153 | */
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154 | cert.issuer = Identity.forHost('**');
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155 |
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156 | var sigBuf = sshbuf.readBuffer();
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157 | cert.signatures.openssh.signature =
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158 | Signature.parse(sigBuf, cert.issuerKey.type, 'ssh');
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159 |
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160 | if (partial !== undefined) {
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161 | partial.remainder = sshbuf.remainder();
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162 | partial.consumed = sshbuf._offset;
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163 | }
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164 |
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165 | return (new Certificate(cert));
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166 | }
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167 |
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168 | function int64ToDate(buf) {
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169 | var i = buf.readUInt32BE(0) * 4294967296;
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170 | i += buf.readUInt32BE(4);
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171 | var d = new Date();
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172 | d.setTime(i * 1000);
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173 | d.sourceInt64 = buf;
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174 | return (d);
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175 | }
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176 |
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177 | function dateToInt64(date) {
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178 | if (date.sourceInt64 !== undefined)
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179 | return (date.sourceInt64);
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180 | var i = Math.round(date.getTime() / 1000);
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181 | var upper = Math.floor(i / 4294967296);
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182 | var lower = Math.floor(i % 4294967296);
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183 | var buf = Buffer.alloc(8);
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184 | buf.writeUInt32BE(upper, 0);
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185 | buf.writeUInt32BE(lower, 4);
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186 | return (buf);
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187 | }
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188 |
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189 | function sign(cert, key) {
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190 | if (cert.signatures.openssh === undefined)
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191 | cert.signatures.openssh = {};
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192 | try {
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193 | var blob = toBuffer(cert, true);
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194 | } catch (e) {
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195 | delete (cert.signatures.openssh);
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196 | return (false);
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197 | }
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198 | var sig = cert.signatures.openssh;
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199 | var hashAlgo = undefined;
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200 | if (key.type === 'rsa' || key.type === 'dsa')
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201 | hashAlgo = 'sha1';
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202 | var signer = key.createSign(hashAlgo);
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203 | signer.write(blob);
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204 | sig.signature = signer.sign();
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205 | return (true);
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206 | }
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207 |
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208 | function signAsync(cert, signer, done) {
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209 | if (cert.signatures.openssh === undefined)
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210 | cert.signatures.openssh = {};
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211 | try {
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212 | var blob = toBuffer(cert, true);
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213 | } catch (e) {
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214 | delete (cert.signatures.openssh);
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215 | done(e);
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216 | return;
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217 | }
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218 | var sig = cert.signatures.openssh;
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219 |
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220 | signer(blob, function (err, signature) {
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221 | if (err) {
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222 | done(err);
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223 | return;
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224 | }
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225 | try {
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226 | /*
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227 | * This will throw if the signature isn't of a
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228 | * type/algo that can be used for SSH.
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229 | */
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230 | signature.toBuffer('ssh');
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231 | } catch (e) {
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232 | done(e);
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233 | return;
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234 | }
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235 | sig.signature = signature;
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236 | done();
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237 | });
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238 | }
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239 |
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240 | function write(cert, options) {
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241 | if (options === undefined)
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242 | options = {};
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243 |
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244 | var blob = toBuffer(cert);
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245 | var out = getCertType(cert.subjectKey) + ' ' + blob.toString('base64');
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246 | if (options.comment)
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247 | out = out + ' ' + options.comment;
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248 | return (out);
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249 | }
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250 |
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251 |
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252 | function toBuffer(cert, noSig) {
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253 | assert.object(cert.signatures.openssh, 'signature for openssh format');
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254 | var sig = cert.signatures.openssh;
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255 |
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256 | if (sig.nonce === undefined)
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257 | sig.nonce = crypto.randomBytes(16);
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258 | var buf = new SSHBuffer({});
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259 | buf.writeString(getCertType(cert.subjectKey));
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260 | buf.writeBuffer(sig.nonce);
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261 |
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262 | var key = cert.subjectKey;
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263 | var algInfo = algs.info[key.type];
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264 | algInfo.parts.forEach(function (part) {
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265 | buf.writePart(key.part[part]);
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266 | });
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267 |
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268 | buf.writeInt64(cert.serial);
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269 |
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270 | var type = cert.subjects[0].type;
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271 | assert.notStrictEqual(type, 'unknown');
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272 | cert.subjects.forEach(function (id) {
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273 | assert.strictEqual(id.type, type);
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274 | });
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275 | type = TYPES[type];
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276 | buf.writeInt(type);
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277 |
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278 | if (sig.keyId === undefined) {
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279 | sig.keyId = cert.subjects[0].type + '_' +
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280 | (cert.subjects[0].uid || cert.subjects[0].hostname);
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281 | }
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282 | buf.writeString(sig.keyId);
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283 |
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284 | var sub = new SSHBuffer({});
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285 | cert.subjects.forEach(function (id) {
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286 | if (type === TYPES.host)
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287 | sub.writeString(id.hostname);
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288 | else if (type === TYPES.user)
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289 | sub.writeString(id.uid);
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290 | });
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291 | buf.writeBuffer(sub.toBuffer());
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292 |
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293 | buf.writeInt64(dateToInt64(cert.validFrom));
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294 | buf.writeInt64(dateToInt64(cert.validUntil));
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295 |
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296 | var exts = sig.exts;
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297 | if (exts === undefined)
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298 | exts = [];
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299 |
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300 | var extbuf = new SSHBuffer({});
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301 | exts.forEach(function (ext) {
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302 | if (ext.critical !== true)
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303 | return;
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304 | extbuf.writeString(ext.name);
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305 | extbuf.writeBuffer(ext.data);
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306 | });
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307 | buf.writeBuffer(extbuf.toBuffer());
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308 |
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309 | extbuf = new SSHBuffer({});
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310 | exts.forEach(function (ext) {
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311 | if (ext.critical === true)
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312 | return;
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313 | extbuf.writeString(ext.name);
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314 | extbuf.writeBuffer(ext.data);
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315 | });
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316 | buf.writeBuffer(extbuf.toBuffer());
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317 |
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318 | /* reserved */
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319 | buf.writeBuffer(Buffer.alloc(0));
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320 |
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321 | sub = rfc4253.write(cert.issuerKey);
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322 | buf.writeBuffer(sub);
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323 |
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324 | if (!noSig)
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325 | buf.writeBuffer(sig.signature.toBuffer('ssh'));
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326 |
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327 | return (buf.toBuffer());
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328 | }
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329 |
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330 | function getAlg(certType) {
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331 | if (certType === 'ssh-rsa-cert-v01@openssh.com')
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332 | return ('rsa');
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333 | if (certType === 'ssh-dss-cert-v01@openssh.com')
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334 | return ('dsa');
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335 | if (certType.match(ECDSA_ALGO))
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336 | return ('ecdsa');
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337 | if (certType === 'ssh-ed25519-cert-v01@openssh.com')
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338 | return ('ed25519');
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339 | throw (new Error('Unsupported cert type ' + certType));
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340 | }
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341 |
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342 | function getCertType(key) {
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343 | if (key.type === 'rsa')
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344 | return ('ssh-rsa-cert-v01@openssh.com');
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345 | if (key.type === 'dsa')
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346 | return ('ssh-dss-cert-v01@openssh.com');
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347 | if (key.type === 'ecdsa')
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348 | return ('ecdsa-sha2-' + key.curve + '-cert-v01@openssh.com');
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349 | if (key.type === 'ed25519')
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350 | return ('ssh-ed25519-cert-v01@openssh.com');
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351 | throw (new Error('Unsupported key type ' + key.type));
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352 | }
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