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August 29, 2015 14:26
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convert openssh id_rsa.pub to modulus and exponent
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#!/usr/bin/env node | |
// requires | |
var forge = require('node-forge'); | |
var fs = require("fs"); | |
// init | |
var sshpubkey = {}; | |
var pubkey; | |
// process command line arguments : pubkeyFile | |
var argv = process.argv; | |
var pubkeyfile = argv[2]; | |
// get pubkeyfile | |
var home = process.env[(process.platform === 'win32') ? 'USERPROFILE' : 'HOME']; | |
if (!pubkeyfile) { | |
pubkeyfile = home + '/.ssh/id_rsa.pub'; | |
} | |
console.log('getting public key from : ' + pubkeyfile); | |
try { | |
pubkey = fs.readFileSync(pubkeyfile, "utf8"); | |
} catch(e) { | |
console.log('could not load : ' + pubkeyfile); | |
process.exit(-1); | |
} | |
// get prefix | |
sshpubkey.prefix = pubkey.toString().split(' ')[0]; | |
sshpubkey.mainkey = pubkey.toString().split(' ')[1]; | |
sshpubkey.keybytes = forge.util.decode64(sshpubkey.mainkey); | |
sshpubkey.keyhex = forge.util.bytesToHex(sshpubkey.keybytes); | |
sshpubkey.byteslen = 4; | |
// type | |
// | |
// | |
sshpubkey.typelenstart = 0; | |
sshpubkey.typelenend = sshpubkey.typelenstart + sshpubkey.byteslen; | |
sshpubkey.typelenbytes = sshpubkey.keybytes.slice(sshpubkey.typelenstart, sshpubkey.typelenend); | |
sshpubkey.typelen = sshpubkey.typelenbytes.charCodeAt(sshpubkey.byteslen-1); | |
sshpubkey.typestart = sshpubkey.typelenend; | |
sshpubkey.typeend = sshpubkey.typestart + sshpubkey.typelen; | |
sshpubkey.typebytes = sshpubkey.keybytes.slice(sshpubkey.typestart, sshpubkey.typeend); | |
// exponent | |
// | |
// | |
sshpubkey.exponentlenstart = sshpubkey.typeend; | |
sshpubkey.exponentlenend = sshpubkey.exponentlenstart + sshpubkey.byteslen; | |
sshpubkey.exponentlenbytes = sshpubkey.keybytes.slice(sshpubkey.exponentlenstart, sshpubkey.exponentlenend); | |
sshpubkey.exponentlen = sshpubkey.exponentlenbytes.charCodeAt(sshpubkey.byteslen-1); | |
sshpubkey.exponentstart = sshpubkey.exponentlenend; | |
sshpubkey.exponentend = sshpubkey.exponentstart + sshpubkey.exponentlen; | |
sshpubkey.exponentbytes = sshpubkey.keybytes.slice(sshpubkey.exponentstart, sshpubkey.exponentend); | |
// modulus | |
// | |
// | |
sshpubkey.moduluslenstart = sshpubkey.exponentend; | |
sshpubkey.moduluslenend = sshpubkey.moduluslenstart + sshpubkey.byteslen; | |
sshpubkey.moduluslenbytes = sshpubkey.keybytes.slice(sshpubkey.moduluslenstart, sshpubkey.moduluslenend); | |
sshpubkey.moduluslen = 256*sshpubkey.moduluslenbytes.charCodeAt(sshpubkey.byteslen-2) + sshpubkey.moduluslenbytes.charCodeAt(sshpubkey.byteslen-1); | |
sshpubkey.modulusstart = sshpubkey.moduluslenend; | |
sshpubkey.modulusend = sshpubkey.modulusstart + sshpubkey.moduluslen; | |
sshpubkey.modulusbytes = sshpubkey.keybytes.slice(sshpubkey.modulusstart, sshpubkey.modulusend); | |
console.log(parseInt(forge.util.bytesToHex(sshpubkey.exponentbytes), 16)); | |
console.log(forge.util.bytesToHex(sshpubkey.modulusbytes)); |
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