text: 
  /*!
   *  Copyright 2010 LearnBoost <dev@learnboost.com>
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  /**
   * Module dependencies.
   */
  
  var crypto = require('crypto')
    , parse = require('url').parse
    ;
  
  /**
   * Valid keys.
   */
  
  var keys = 
    [ 'acl'
    , 'location'
    , 'logging'
    , 'notification'
    , 'partNumber'
    , 'policy'
    , 'requestPayment'
    , 'torrent'
    , 'uploadId'
    , 'uploads'
    , 'versionId'
    , 'versioning'
    , 'versions'
    , 'website'
    ]
  
  /**
   * Return an "Authorization" header value with the given `options`
   * in the form of "AWS <key>:<signature>"
   *
   * @param {Object} options
   * @return {String}
   * @api private
   */
  
  function authorization (options) {
    return 'AWS ' + options.key + ':' + sign(options)
  }
  
  module.exports = authorization
  module.exports.authorization = authorization
  
  /**
   * Simple HMAC-SHA1 Wrapper
   *
   * @param {Object} options
   * @return {String}
   * @api private
   */ 
  
  function hmacSha1 (options) {
    return crypto.createHmac('sha1', options.secret).update(options.message).digest('base64')
  }
  
  module.exports.hmacSha1 = hmacSha1
  
  /**
   * Create a base64 sha1 HMAC for `options`. 
   * 
   * @param {Object} options
   * @return {String}
   * @api private
   */
  
  function sign (options) {
    options.message = stringToSign(options)
    return hmacSha1(options)
  }
  module.exports.sign = sign
  
  /**
   * Create a base64 sha1 HMAC for `options`. 
   *
   * Specifically to be used with S3 presigned URLs
   * 
   * @param {Object} options
   * @return {String}
   * @api private
   */
  
  function signQuery (options) {
    options.message = queryStringToSign(options)
    return hmacSha1(options)
  }
  module.exports.signQuery= signQuery
  
  /**
   * Return a string for sign() with the given `options`.
   *
   * Spec:
   * 
   *    <verb>\n
   *    <md5>\n
   *    <content-type>\n
   *    <date>\n
   *    [headers\n]
   *    <resource>
   *
   * @param {Object} options
   * @return {String}
   * @api private
   */
  
  function stringToSign (options) {
    var headers = options.amazonHeaders || ''
    if (headers) headers += '\n'
    var r = 
      [ options.verb
      , options.md5
      , options.contentType
      , options.date ? options.date.toUTCString() : ''
      , headers + options.resource
      ]
    return r.join('\n')
  }
  module.exports.queryStringToSign = stringToSign
  
  /**
   * Return a string for sign() with the given `options`, but is meant exclusively
   * for S3 presigned URLs
   *
   * Spec:
   * 
   *    <date>\n
   *    <resource>
   *
   * @param {Object} options
   * @return {String}
   * @api private
   */
  
  function queryStringToSign (options){
    return 'GET\n\n\n' + options.date + '\n' + options.resource
  }
  module.exports.queryStringToSign = queryStringToSign
  
  /**
   * Perform the following:
   *
   *  - ignore non-amazon headers
   *  - lowercase fields
   *  - sort lexicographically
   *  - trim whitespace between ":"
   *  - join with newline
   *
   * @param {Object} headers
   * @return {String}
   * @api private
   */
  
  function canonicalizeHeaders (headers) {
    var buf = []
      , fields = Object.keys(headers)
      ;
    for (var i = 0, len = fields.length; i < len; ++i) {
      var field = fields[i]
        , val = headers[field]
        , field = field.toLowerCase()
        ;
      if (0 !== field.indexOf('x-amz')) continue
      buf.push(field + ':' + val)
    }
    return buf.sort().join('\n')
  }
  module.exports.canonicalizeHeaders = canonicalizeHeaders
  
  /**
   * Perform the following:
   *
   *  - ignore non sub-resources
   *  - sort lexicographically
   *
   * @param {String} resource
   * @return {String}
   * @api private
   */
  
  function canonicalizeResource (resource) {
    var url = parse(resource, true)
      , path = url.pathname
      , buf = []
      ;
  
    Object.keys(url.query).forEach(function(key){
      if (!~keys.indexOf(key)) return
      var val = '' == url.query[key] ? '' : '=' + encodeURIComponent(url.query[key])
      buf.push(key + val)
    })
  
    return path + (buf.length ? '?' + buf.sort().join('&') : '')
  }
  module.exports.canonicalizeResource = canonicalizeResource
  