text: // Copyright 2015 Joyent, Inc.
  
  module.exports = {
  	read: read,
  	write: write
  };
  
  var assert = require('assert-plus');
  var utils = require('../utils');
  var Key = require('../key');
  var PrivateKey = require('../private-key');
  
  var pem = require('./pem');
  var ssh = require('./ssh');
  var rfc4253 = require('./rfc4253');
  var dnssec = require('./dnssec');
  
  var DNSSEC_PRIVKEY_HEADER_PREFIX = 'Private-key-format: v1';
  
  function read(buf, options) {
  	if (typeof (buf) === 'string') {
  		if (buf.trim().match(/^[-]+[ ]*BEGIN/))
  			return (pem.read(buf, options));
  		if (buf.match(/^\s*ssh-[a-z]/))
  			return (ssh.read(buf, options));
  		if (buf.match(/^\s*ecdsa-/))
  			return (ssh.read(buf, options));
  		if (findDNSSECHeader(buf))
  			return (dnssec.read(buf, options));
  		buf = new Buffer(buf, 'binary');
  	} else {
  		assert.buffer(buf);
  		if (findPEMHeader(buf))
  			return (pem.read(buf, options));
  		if (findSSHHeader(buf))
  			return (ssh.read(buf, options));
  		if (findDNSSECHeader(buf))
  			return (dnssec.read(buf, options));
  	}
  	if (buf.readUInt32BE(0) < buf.length)
  		return (rfc4253.read(buf, options));
  	throw (new Error('Failed to auto-detect format of key'));
  }
  
  function findSSHHeader(buf) {
  	var offset = 0;
  	while (offset < buf.length &&
  	    (buf[offset] === 32 || buf[offset] === 10 || buf[offset] === 9))
  		++offset;
  	if (offset + 4 <= buf.length &&
  	    buf.slice(offset, offset + 4).toString('ascii') === 'ssh-')
  		return (true);
  	if (offset + 6 <= buf.length &&
  	    buf.slice(offset, offset + 6).toString('ascii') === 'ecdsa-')
  		return (true);
  	return (false);
  }
  
  function findPEMHeader(buf) {
  	var offset = 0;
  	while (offset < buf.length &&
  	    (buf[offset] === 32 || buf[offset] === 10))
  		++offset;
  	if (buf[offset] !== 45)
  		return (false);
  	while (offset < buf.length &&
  	    (buf[offset] === 45))
  		++offset;
  	while (offset < buf.length &&
  	    (buf[offset] === 32))
  		++offset;
  	if (offset + 5 > buf.length ||
  	    buf.slice(offset, offset + 5).toString('ascii') !== 'BEGIN')
  		return (false);
  	return (true);
  }
  
  function findDNSSECHeader(buf) {
  	// private case first
  	if (buf.length <= DNSSEC_PRIVKEY_HEADER_PREFIX.length)
  		return (false);
  	var headerCheck = buf.slice(0, DNSSEC_PRIVKEY_HEADER_PREFIX.length);
  	if (headerCheck.toString('ascii') === DNSSEC_PRIVKEY_HEADER_PREFIX)
  		return (true);
  
  	// public-key RFC3110 ?
  	// 'domain.com. IN KEY ...' or 'domain.com. IN DNSKEY ...'
  	// skip any comment-lines
  	if (typeof (buf) !== 'string') {
  		buf = buf.toString('ascii');
  	}
  	var lines = buf.split('\n');
  	var line = 0;
  	/* JSSTYLED */
  	while (lines[line].match(/^\;/))
  		line++;
  	if (lines[line].toString('ascii').match(/\. IN KEY /))
  		return (true);
  	if (lines[line].toString('ascii').match(/\. IN DNSKEY /))
  		return (true);
  	return (false);
  }
  
  function write(key, options) {
  	throw (new Error('"auto" format cannot be used for writing'));
  }
  