Como automatizar a geração de senhas do Windows

Com o comando gcloud compute reset-windows-password, um usuário que tem acesso de gravação ao projeto do Compute Engine recupera, de maneira segura, as senhas das contas nas instâncias do Windows.

Primeiro, um nome de usuário e uma chave pública RSA são enviados à instância. O agente em execução na instância faz um dos procedimentos a seguir:

  • cria uma conta para esse nome de usuário e gera uma senha aleatória;
  • a senha é redefinida como um valor aleatório caso a conta já exista.

A senha é criptografada pelo agente com a chave pública fornecida e enviada de volta ao cliente para ser descriptografada com a chave privada correspondente.

Nesta seção, há uma descrição desse processo e alguns scripts de exemplo em que essas etapas são reproduzidas por meio de programação. Se você quiser seguir essas etapas manualmente, leia a seção Instruções manuais.

Antes de começar

Automatizar a geração de senhas

Go


//  Copyright 2018 Google Inc. All Rights Reserved.
//
//  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.

package main

import (
	"context"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha1"
	"encoding/base64"
	"encoding/binary"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"log"
	"strings"
	"time"

	daisyCompute "github.com/GoogleCloudPlatform/compute-image-tools/daisy/compute"
	"google.golang.org/api/compute/v1"
)

var (
	instance = flag.String("instance", "", "instance to reset password on")
	zone     = flag.String("zone", "", "zone instance is in")
	project  = flag.String("project", "", "project instance is in")
	user     = flag.String("user", "", "user to reset password for")
)

func getInstanceMetadata(client daisyCompute.Client, i, z, p string) (*compute.Metadata, error) {
	ins, err := client.GetInstance(p, z, i)
	if err != nil {
		return nil, fmt.Errorf("error getting instance: %v", err)
	}

	return ins.Metadata, nil
}

type windowsKeyJSON struct {
	ExpireOn string
	Exponent string
	Modulus  string
	UserName string
}

func generateKey(priv *rsa.PublicKey, u string) (*windowsKeyJSON, error) {
	bs := make([]byte, 4)
	binary.BigEndian.PutUint32(bs, uint32(priv.E))

	return &windowsKeyJSON{
		ExpireOn: time.Now().Add(5 * time.Minute).Format(time.RFC3339),
		// This is different than what the other tools produce,
		// AQAB vs AQABAA==, both are decoded as 65537.
		Exponent: base64.StdEncoding.EncodeToString(bs),
		Modulus:  base64.StdEncoding.EncodeToString(priv.N.Bytes()),
		UserName: u,
	}, nil
}

type credsJSON struct {
	ErrorMessage      string `json:"errorMessage,omitempty"`
	EncryptedPassword string `json:"encryptedPassword,omitempty"`
	Modulus           string `json:"modulus,omitempty"`
}

func getEncryptedPassword(client daisyCompute.Client, i, z, p, mod string) (string, error) {
	out, err := client.GetSerialPortOutput(p, z, i, 4, 0)
	if err != nil {
		return "", err
	}

	for _, line := range strings.Split(out.Contents, "\n") {
		var creds credsJSON
		if err := json.Unmarshal([]byte(line), &creds); err != nil {
			continue
		}
		if creds.Modulus == mod {
			if creds.ErrorMessage != "" {
				return "", fmt.Errorf("error from agent: %s", creds.ErrorMessage)
			}
			return creds.EncryptedPassword, nil
		}
	}
	return "", errors.New("password not found in serial output")
}

func decryptPassword(priv *rsa.PrivateKey, ep string) (string, error) {
	bp, err := base64.StdEncoding.DecodeString(ep)
	if err != nil {
		return "", fmt.Errorf("error decoding password: %v", err)
	}
	pwd, err := rsa.DecryptOAEP(sha1.New(), rand.Reader, priv, bp, nil)
	if err != nil {
		return "", fmt.Errorf("error decrypting password: %v", err)
	}
	return string(pwd), nil
}

func resetPassword(client daisyCompute.Client, i, z, p, u string) (string, error) {
	md, err := getInstanceMetadata(client, *instance, *zone, *project)
	if err != nil {
		return "", fmt.Errorf("error getting instance metadata: %v", err)
	}

	fmt.Println("Generating public/private key pair")
	key, err := rsa.GenerateKey(rand.Reader, 2048)
	if err != nil {
		return "", err
	}

	winKey, err := generateKey(&key.PublicKey, u)
	if err != nil {
		return "", err
	}

	data, err := json.Marshal(winKey)
	if err != nil {
		return "", err
	}

	winKeys := string(data)
	var found bool
	for _, mdi := range md.Items {
		if mdi.Key == "windows-keys" {
			val := fmt.Sprintf("%s\n%s", *mdi.Value, winKeys)
			mdi.Value = &val
			found = true
			break
		}
	}
	if !found {
		md.Items = append(md.Items, &compute.MetadataItems{Key: "windows-keys", Value: &winKeys})
	}

	fmt.Println("Setting new 'windows-keys' metadata")
	if err := client.SetInstanceMetadata(p, z, i, md); err != nil {
		return "", err
	}

	fmt.Println("Fetching encrypted password")
	var trys int
	var ep string
	for {
		time.Sleep(1 * time.Second)
		ep, err = getEncryptedPassword(client, i, z, p, winKey.Modulus)
		if err == nil {
			break
		}
		if trys > 10 {
			return "", err
		}
		trys++
	}

	fmt.Println("Decrypting password")
	return decryptPassword(key, ep)
}

func main() {
	flag.Parse()
	if *instance == "" {
		log.Fatal("-instance flag required")
	}
	if *zone == "" {
		log.Fatal("-zone flag required")
	}
	if *project == "" {
		log.Fatal("-project flag required")
	}
	if *user == "" {
		log.Fatal("-user flag required")
	}

	ctx := context.Background()
	client, err := daisyCompute.NewClient(ctx)
	if err != nil {
		log.Fatalf("Error creating compute service: %v", err)
	}

	fmt.Printf("Resetting password on instance %q for user %q\n", *instance, *user)
	pw, err := resetPassword(client, *instance, *zone, *project, *user)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("- Username: %s\n- Password: %s\n", *user, pw)
}

Python


#!/usr/bin/env python

# Copyright 2015 Google Inc. All Rights Reserved.
#
# 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.

import base64
import copy
import datetime
import json
import time

# PyCrypto library: https://pypi.python.org/pypi/pycrypto
from Crypto.Cipher import PKCS1_OAEP
from Crypto.PublicKey import RSA
from Crypto.Util.number import long_to_bytes

# Google API Client Library for Python:
# https://developers.google.com/api-client-library/python/start/get_started
from oauth2client.client import GoogleCredentials
from googleapiclient.discovery import build

def GetCompute():
    """Get a compute object for communicating with the Compute Engine API."""
    credentials = GoogleCredentials.get_application_default()
    compute = build('compute', 'v1', credentials=credentials)
    return compute

def GetInstance(compute, instance, zone, project):
    """Get the data for a Google Compute Engine instance."""
    cmd = compute.instances().get(instance=instance, project=project,
                                  zone=zone)
    return cmd.execute()

def GetKey():
    """Get an RSA key for encryption."""
    # This uses the PyCrypto library
    key = RSA.generate(2048)
    return key

def GetModulusExponentInBase64(key):
    """Return the public modulus and exponent for the key in bas64 encoding."""
    mod = long_to_bytes(key.n)
    exp = long_to_bytes(key.e)

    modulus = base64.b64encode(mod)
    exponent = base64.b64encode(exp)

    return modulus, exponent

def GetExpirationTimeString():
    """Return an RFC3339 UTC timestamp for 5 minutes from now."""
    utc_now = datetime.datetime.utcnow()
    # These metadata entries are one-time-use, so the expiration time does
    # not need to be very far in the future. In fact, one minute would
    # generally be sufficient. Five minutes allows for minor variations
    # between the time on the client and the time on the server.
    expire_time = utc_now + datetime.timedelta(minutes=5)
    return expire_time.strftime('%Y-%m-%dT%H:%M:%SZ')

def GetJsonString(user, modulus, exponent, email):
    """Return the JSON string object that represents the windows-keys entry."""
    expire = GetExpirationTimeString()
    data = {'userName': user,
            'modulus': modulus,
            'exponent': exponent,
            'email': email,
            'expireOn': expire}
    return json.dumps(data)

def UpdateWindowsKeys(old_metadata, metadata_entry):
    """Return updated metadata contents with the new windows-keys entry."""
    # Simply overwrites the "windows-keys" metadata entry. Production code may
    # want to append new lines to the metadata value and remove any expired
    # entries.
    new_metadata = copy.deepcopy(old_metadata)
    new_metadata['items'] = [{
        'key': "windows-keys",
        'value': metadata_entry
    }]
    return new_metadata

def UpdateInstanceMetadata(compute, instance, zone, project, new_metadata):
    """Update the instance metadata."""
    cmd = compute.instances().setMetadata(instance=instance, project=project,
                                          zone=zone, body=new_metadata)
    return cmd.execute()

def GetSerialPortFourOutput(compute, instance, zone, project):
    """Get the output from serial port 4 from the instance."""
    # Encrypted passwords are printed to COM4 on the windows server:
    port = 4
    cmd = compute.instances().getSerialPortOutput(instance=instance,
                                                  project=project,
                                                  zone=zone, port=port)
    output = cmd.execute()
    return output['contents']

def GetEncryptedPasswordFromSerialPort(serial_port_output, modulus):
    """Find and return the correct encrypted password, based on the modulus."""
    # In production code, this may need to be run multiple times if the output
    # does not yet contain the correct entry.
    output = serial_port_output.split('\n')
    for line in reversed(output):
        try:
            entry = json.loads(line)
            if modulus == entry['modulus']:
                return entry['encryptedPassword']
        except ValueError:
            pass

def DecryptPassword(encrypted_password, key):
    """Decrypt a base64 encoded encrypted password using the provided key."""
    decoded_password = base64.b64decode(encrypted_password)
    cipher = PKCS1_OAEP.new(key)
    password = cipher.decrypt(decoded_password)
    return password

def main(instance, zone, project, user, email):
    # Setup
    compute = GetCompute()
    key = GetKey()
    modulus, exponent = GetModulusExponentInBase64(key)

    # Get existing metadata
    instance_ref = GetInstance(compute, instance, zone, project)
    old_metadata = instance_ref['metadata']

    # Create and set new metadata
    metadata_entry = GetJsonString(user, modulus,
                                   exponent, email)
    new_metadata = UpdateWindowsKeys(old_metadata, metadata_entry)
    result = UpdateInstanceMetadata(compute, instance, zone, project,
                                    new_metadata)

    # For this sample code, just sleep for 30 seconds instead of checking for
    # responses. In production code, this should monitor the status of the
    # metadata update operation.
    time.sleep(30)

    # Get and decrypt password from serial port output
    serial_port_output = GetSerialPortFourOutput(compute, instance,
                                                 zone, project)
    enc_password = GetEncryptedPasswordFromSerialPort(serial_port_output,
                                                      modulus)
    password = DecryptPassword(enc_password, key)

    # Display the username, password and IP address for the instance
    print 'Username:   {0}'.format(user)
    print 'Password:   {0}'.format(password)
    ip = instance_ref['networkInterfaces'][0]['accessConfigs'][0]['natIP']
    print 'IP Address: {0}'.format(ip)

if __name__ == '__main__':
    instance = 'my-instance'
    zone = 'us-central1-a'
    project = 'my-project'
    user = 'example-user'
    email = 'user@example.com'
    main(instance, zone, project, user, email)

Java


/**
 * Copyright 2015 Google Inc. All Rights Reserved.
 *
 * 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.
 */

/**
 * This package demonstrates how to reset Windows passwords in Java.
 */

package cloud.google.com.windows.example;

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.repackaged.org.apache.commons.codec.binary.Base64;
import com.google.api.services.compute.Compute;
import com.google.api.services.compute.model.Instance;
import com.google.api.services.compute.model.Metadata;
import com.google.api.services.compute.model.Metadata.Items;
import com.google.api.services.compute.model.SerialPortOutput;
import com.google.common.io.BaseEncoding;

import org.json.simple.JSONObject;
import org.json.simple.parser.JSONParser;

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.Security;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.RSAPublicKeySpec;
import java.text.SimpleDateFormat;
import java.util.Arrays;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;
import java.util.TimeZone;

import javax.crypto.Cipher;

public class ExampleCode {

  public ExampleCode() {}

  // Constants used to configure behavior.
  private static final String ZONE_NAME = "us-central1-a";
  private static final String PROJECT_NAME = "example-project-1234";
  private static final String INSTANCE_NAME = "test-instance";
  private static final String APPLICATION_NAME = "windows-pw-reset";

  // Constants for configuring user name, email, and SSH key expiration.
  private static final String USER_NAME = "example_user";
  private static final String EMAIL = "example_user@test.com";

  // Keys are one-time use, so the metadata doesn't need to stay around for long.
  // 5 minutes chosen to allow for differences between time on the client
  // and time on the server.
  private static final long EXPIRE_TIME = 300000;

  // HttpTransport and JsonFactory used to create the Compute object.
  private static HttpTransport httpTransport;
  private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();

  public static void main(String[] args) {
    ExampleCode ec = new ExampleCode();
    try {
      // Initialize Transport object.
      httpTransport = GoogleNetHttpTransport.newTrustedTransport();

      // Reset the password.
      ec.resetPassword();
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
  }

  public void resetPassword() throws Exception {
    // Get credentials to setup a connection with the Compute API.
    Credential cred = GoogleCredential.getApplicationDefault();

    // Create an instance of the Compute API.
    Compute compute = new Compute.Builder(httpTransport, JSON_FACTORY, null)
        .setApplicationName(APPLICATION_NAME).setHttpRequestInitializer(cred).build();

    // Get the instance object to gain access to the instance's metadata.
    Instance inst = compute.instances().get(PROJECT_NAME, ZONE_NAME, INSTANCE_NAME).execute();
    Metadata metadata = inst.getMetadata();

    // Generate the public/private key pair for encryption and decryption.
    KeyPair keys = generateKeys();

    // Update metadata from instance with new windows-keys entry.
    replaceMetadata(metadata, buildKeyMetadata(keys));

    // Tell Compute Engine to update the instance metadata with our changes.
    compute.instances().setMetadata(PROJECT_NAME, ZONE_NAME, INSTANCE_NAME, metadata).execute();

    System.out.println("Updating metadata...");

    // Sleep while waiting for metadata to propagate - production code may
    // want to monitor the status of the metadata update operation.
    Thread.sleep(30000);

    System.out.println("Getting serial output...");

    // Request the output from serial port 4.
    // In production code, this operation should be polled.
    SerialPortOutput output = compute.instances()
        .getSerialPortOutput(PROJECT_NAME, ZONE_NAME, INSTANCE_NAME).setPort(4).execute();

    // Get the last line - this will be a JSON string corresponding to the
    // most recent password reset attempt.
    String[] entries = output.getContents().split("\n");
    String outputEntry = entries[entries.length - 1];

    // Parse output using the json-simple library.
    JSONParser parser = new JSONParser();
    JSONObject passwordDict = (JSONObject) parser.parse(outputEntry);

    String encryptedPassword = passwordDict.get("encryptedPassword").toString();

    // Output user name and decrypted password.
    System.out.println("\nUser name: " + passwordDict.get("userName").toString());
    System.out.println("Password: " + decryptPassword(encryptedPassword, keys));
  }

  private String decryptPassword(String message, KeyPair keys) {
    try {
      // Add the bouncycastle provider - the built-in providers don't support RSA
      // with OAEPPadding.
      Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());

      // Get the appropriate cipher instance.
      Cipher rsa = Cipher.getInstance("RSA/NONE/OAEPPadding", "BC");

      // Add the private key for decryption.
      rsa.init(Cipher.DECRYPT_MODE, keys.getPrivate());

      // Decrypt the text.
      byte[] rawMessage = Base64.decodeBase64(message);
      byte[] decryptedText = rsa.doFinal(rawMessage);

      // The password was encoded using UTF8. Transform into string.
      return new String(decryptedText, "UTF8");
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
    return "";
  }

  private void replaceMetadata(Metadata input, JSONObject newMetadataItem) {
    // Transform the JSON object into a string that the API can use.
    String newItemString = newMetadataItem.toJSONString();

    // Get the list containing all of the Metadata entries for this instance.
    List<Items> items = input.getItems();

    // If the instance has no metadata, items can be returned as null.
    if (items == null)
    {
      items = new LinkedList<Items>();
      input.setItems(items);
    }

    // Find the "windows-keys" entry and update it.
    for (Items item : items) {
      if (item.getKey().compareTo("windows-keys") == 0) {
        // Replace item's value with the new entry.
        // To prevent race conditions, production code may want to maintain a
        // list where the oldest entries are removed once the 32KB limit is
        // reached for the metadata entry.
        item.setValue(newItemString);
        return;
      }
    }

    // "windows.keys" entry doesn't exist in the metadata - append it.
    // This occurs when running password-reset for the first time on an instance.
    items.add(new Items().setKey("windows-keys").setValue(newItemString));
  }

  private KeyPair generateKeys() throws NoSuchAlgorithmException {
    KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");

    // Key moduli for encryption/decryption are 2048 bits long.
    keyGen.initialize(2048);

    return keyGen.genKeyPair();
  }

  @SuppressWarnings("unchecked")
  private JSONObject buildKeyMetadata(KeyPair pair) throws NoSuchAlgorithmException,
      InvalidKeySpecException {
    // Object used for storing the metadata values.
    JSONObject metadataValues = new JSONObject();

    // Encode the public key into the required JSON format.
    metadataValues.putAll(jsonEncode(pair));

    // Add username and email.
    metadataValues.put("userName", USER_NAME);
    metadataValues.put("email", EMAIL);

    // Create the date on which the new keys expire.
    Date now = new Date();
    Date expireDate = new Date(now.getTime() + EXPIRE_TIME);

    // Format the date to match rfc3339.
    SimpleDateFormat rfc3339Format = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
    rfc3339Format.setTimeZone(TimeZone.getTimeZone("UTC"));
    String dateString = rfc3339Format.format(expireDate);

    // Encode the expiration date for the returned JSON dictionary.
    metadataValues.put("expireOn", dateString);

    return metadataValues;
  }

  @SuppressWarnings("unchecked")
  private JSONObject jsonEncode(KeyPair keys) throws NoSuchAlgorithmException,
      InvalidKeySpecException {
    KeyFactory factory = KeyFactory.getInstance("RSA");

    // Get the RSA spec for key manipulation.
    RSAPublicKeySpec pubSpec = factory.getKeySpec(keys.getPublic(), RSAPublicKeySpec.class);

    // Extract required parts of the key.
    BigInteger modulus = pubSpec.getModulus();
    BigInteger exponent = pubSpec.getPublicExponent();

    // Grab an encoder for the modulus and exponent to encode using RFC 3548;
    // Java SE 7 requires an external library (Google's Guava used here)
    // Java SE 8 has a built-in Base64 class that can be used instead. Apache also has an RFC 3548
    // encoder.
    BaseEncoding stringEncoder = BaseEncoding.base64();

    // Strip out the leading 0 byte in the modulus.
    byte[] arr = Arrays.copyOfRange(modulus.toByteArray(), 1, modulus.toByteArray().length);

    JSONObject returnJson = new JSONObject();

    // Encode the modulus, add to returned JSON object.
    String modulusString = stringEncoder.encode(arr).replaceAll("\n", "");
    returnJson.put("modulus", modulusString);

    // Encode exponent, add to returned JSON object.
    String exponentString = stringEncoder.encode(exponent.toByteArray()).replaceAll("\n", "");
    returnJson.put("exponent", exponentString);

    return returnJson;
  }
}

Instruções manuais

Nas etapas deste guia manual, o OpenSSL é usado nas funções criptográficas e as ferramentas do shell Bash/Linux em algumas outras funções, mas diversas implementações são possíveis.

  1. Gere um par de chaves RSA de 2048 bits. No OpenSSL, gere esse par de chaves executando:

    $ openssl genrsa -out private_key 2048
    

    Com esse comando, é criado um arquivo chamado private_key. O conteúdo dele se assemelha a este:

    $ cat private_key
    -----BEGIN RSA PRIVATE KEY-----
    MIIEpAIBAAKCAQEAwgsquN4IBNPqIUnu+h/5Za1kujb2YRhX1vCQVQAkBwnWigcC
    qOBVfRa5JoZfx6KIvEXjWqa77jPvlsxM4WPqnDIM2qiK36up3SKkYwFjff6F2ni/
    ry8vrwXCX3sGZ1hbIHlK0O012HpA3ISeEswVZmX2X67naOvJXfY5v0hGPWqCADao
    +xVxrmxsZD4IWnKl1UaZzI5lhAzr8fw6utHwx1EZ/MSgsEki6tujcZfN+GUDRnmJ
    GQSnPTXmsf7Q4DKreTZk49cuyB3prV91S0x3DYjCUpSXrkVy1Ha5XicGD/q+ystu
    FsJnrrhbNXJbpSjM6sjo/aduAkZJl4FmOt0R7QIDAQABAoIBAQCsT6hHc/tg9iIC
    H5pUiRI55Uj+R5JwVGKkXwl8Qdy8V1MpTOJivpuLsiMGf+sL51xO/CzRsiBOfdYz
    bgaTW9vZimR5w5NW3iTAV2Ps+y2zk9KfV/y3/0nzvUSG70OXgBGj+7GhaBQZwS5Z
    5HZOsOYMAV1QSIv8Uu2FQAK1xuOA4seJ/NK42iXgVB1XvYe2AxCWNqCBJylk9F5N
    8a213oJWw2mwQWCSfZhuvwYRO7w/V+mInKPkKlWvf3SLuMCWeDI8s0jLsJMQ0rbp
    jYXRzc2G+LF1aLxjatiGeLsqfVYerNohufGAajpNkSvcMciDXvD9aJhZqior+x2Q
    rCnMuNRNAoGBAPI6r32wIf8H9GmcvGrXk9OYLq0uJGqAtJDgGmJM5BSX4mlSz+Ni
    SYlQOfi24ykQDo3XbA59Lb6H0L64czi2a3OmpG8s6h4ymp+3cSd1k1AER1oZudwH
    9UScGfSgT/nMgufBwEGlQkCMp5x4Sl20clCHZ49p9eNiXML3wxpCZPIjAoGBAM0T
    NKt/rjqMs0qOWAJKemSPk0zV+1RSjCoOdKC6jmHRGr/MIoKiJLIkywV2m53yv8Wu
    BF3gVUDlwojoOKcVR8588tek5L0j9RshGovKj4Uxz9uPPhzeNnlSA+5PS284VtKz
    LX8xZ/b+MNCyor9jT0qoWylqym0w+M4aFL2tUQSvAoGABJvnQO38B51AIk5QK3xE
    nM8VfEgXe0tNpEAPYHV0FYw6S6S+veXd3lX/dGMOeXaLwFkr/i6Vkz2EVEywLJEU
    BFRUZqUlI0P1OzrDVWvgTLJ4JRe+OJiSKycJO2VdgDRK/Vvra5RYaWADxG9pgtTv
    I+cfqlPq0NPLTg5m0PYYc58CgYBpGt/SygTNA1Hc82mN+wgRxDhVmBJRHGG0KGaD
    /jl9TsOr638AfwPZvdvD+A83+7NoKJEaYCCxu1BiBMsMb263GPkJpvyJKAW2mtfV
    L8MxG9+Rgy/tccJvmaZkHIXoAfMV2DmISBUl1Q/F1thsyQRZmkHmz1Hidsf+MgXR
    VSQCBwKBgQCxwJtGZGPdQbDXcZZtL0yJJIbdt5Q/TrW0es17IPAoze+E6zFg9mo7
    ea9AuGxOGDQwO9n5DBn/3XcSjRnhvXaW60Taz6ZC60Zh/s6IilCmav+n9ewFHJ3o
    AglSJZRJ1Eer0m5m6s2FW5U0Yjthxwkm3WCWS61cOOTvb6xhQ5+WSw==
    -----END RSA PRIVATE KEY-----
    
  2. Gere uma chave pública. Para criar a chave pública, execute:

    $ openssl rsa -pubout -in private_key -out public_key
    

    Com esse comando, um arquivo chamado public_key é criado, semelhante a este:

    $ cat public_key
    -----BEGIN PUBLIC KEY-----
    MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAwgsquN4IBNPqIUnu+h/5
    Za1kujb2YRhX1vCQVQAkBwnWigcCqOBVfRa5JoZfx6KIvEXjWqa77jPvlsxM4WPq
    nDIM2qiK36up3SKkYwFjff6F2ni/ry8vrwXCX3sGZ1hbIHlK0O012HpA3ISeEswV
    ZmX2X67naOvJXfY5v0hGPWqCADao+xVxrmxsZD4IWnKl1UaZzI5lhAzr8fw6utHw
    x1EZ/MSgsEki6tujcZfN+GUDRnmJGQSnPTXmsf7Q4DKreTZk49cuyB3prV91S0x3
    DYjCUpSXrkVy1Ha5XicGD/q+ystuFsJnrrhbNXJbpSjM6sjo/aduAkZJl4FmOt0R
    7QIDAQAB
    -----END PUBLIC KEY-----
    
  3. Extraia o módulo e o expoente. As chaves pública e privada são formadas por um módulo e um expoente. Na chave pública, extraia o módulo e o expoente:

    $ openssl rsa -in public_key -pubin -text -noout
    Public-Key: (2048 bit)
    Modulus:
        00:c2:0b:2a:b8:de:08:04:d3:ea:21:49:ee:fa:1f:
        f9:65:ad:64:ba:36:f6:61:18:57:d6:f0:90:55:00:
        24:07:09:d6:8a:07:02:a8:e0:55:7d:16:b9:26:86:
        5f:c7:a2:88:bc:45:e3:5a:a6:bb:ee:33:ef:96:cc:
        4c:e1:63:ea:9c:32:0c:da:a8:8a:df:ab:a9:dd:22:
        a4:63:01:63:7d:fe:85:da:78:bf:af:2f:2f:af:05:
        c2:5f:7b:06:67:58:5b:20:79:4a:d0:ed:35:d8:7a:
        40:dc:84:9e:12:cc:15:66:65:f6:5f:ae:e7:68:eb:
        c9:5d:f6:39:bf:48:46:3d:6a:82:00:36:a8:fb:15:
        71:ae:6c:6c:64:3e:08:5a:72:a5:d5:46:99:cc:8e:
        65:84:0c:eb:f1:fc:3a:ba:d1:f0:c7:51:19:fc:c4:
        a0:b0:49:22:ea:db:a3:71:97:cd:f8:65:03:46:79:
        89:19:04:a7:3d:35:e6:b1:fe:d0:e0:32:ab:79:36:
        64:e3:d7:2e:c8:1d:e9:ad:5f:75:4b:4c:77:0d:88:
        c2:52:94:97:ae:45:72:d4:76:b9:5e:27:06:0f:fa:
        be:ca:cb:6e:16:c2:67:ae:b8:5b:35:72:5b:a5:28:
        cc:ea:c8:e8:fd:a7:6e:02:46:49:97:81:66:3a:dd:
        11:ed
    Exponent: 65537 (0x10001)
    
  4. Codifique o módulo e o expoente. É preciso extrair e codificar o módulo e o expoente em base64. Antes de codificar o módulo, remova o byte zero inicial. Por padrão, o arquivo public_key já é uma string de bytes codificada em base64 com as seguintes informações:

    • 32 bytes de informações de cabeçalho
    • 1 byte com o zero inicial do módulo
    • 256 bytes do módulo
    • 2 bytes do cabeçalho do expoente
    • 3 bytes do expoente

    É necessário extrair e codificar o módulo e o expoente separadamente do restante do conteúdo do arquivo. Extraia e codifique o módulo e o expoente usando os seguintes comandos:

    $ cat public_key | grep -v -- ----- | base64 -d | dd bs=1 skip=33 count=256 2>/dev/null | base64 -w 0; echo
            wgsquN4IBNPqIUnu+h/5Za1kujb2YRhX1vCQVQAkBwnWigcCqOBVfRa5JoZfx6KIvEXjWqa77jPvlsx
    M4WPqnDIM2qiK36up3SKkYwFjff6F2ni/ry8vrwXCX3sGZ1hbIHlK0O012HpA3ISeEswVZmX2X67naO
    vJXfY5v0hGPWqCADao+xVxrmxsZD4IWnKl1UaZzI5lhAzr8fw6utHwx1EZ/MSgsEki6tujcZfN+GUDR
    nmJGQSnPTXmsf7Q4DKreTZk49cuyB3prV91S0x3DYjCUpSXrkVy1Ha5XicGD/q+ystuFsJnrrhbNXJb
    pSjM6sjo/aduAkZJl4FmOt0R7Q==
    
    $ cat public_key | grep -v -- ----- | base64 -d | dd bs=1 skip=291 count=3 2>/dev/null | base64
    AQAB
    

    Caso você tenha problemas na codificação do módulo, verifique se removeu o byte zero inicial do módulo antes de iniciar o processo.

  5. Crie um objeto JSON com nome de usuário e informações de chave pública. Inclua os seguintes dados:

    • userName: o nome de usuário usado para fazer login na instância.
    • modulus: os módulos da chave pública codificados no formato base64.
    • exponent: o expoente da chave pública codificado no formato base64.
    • email: o endereço de e-mail do usuário que está solicitando a senha. Use o endereço de e-mail da Conta do Google que está autenticado na API.
    • expireOn: um carimbo de data/hora codificado em RFC 3399 com as informações de quando a chave expira. Ele precisa estar no fuso horário UTC, aproximadamente cinco minutos adiantado. Como essas chaves são usadas apenas para gerar o nome de usuário e a senha, elas deixam de ser necessárias depois que a senha é criada. As chaves expiradas não são usadas no agente.

    Exemplo:

    {\"userName\": \"example-user\",  \"modulus\": \"wgsquN4IBNPqIUnu+h/5Za1kujb2YRhX1
    vCQVQAkBwnWigcCqOBVfRa5JoZfx6KIvEXjWqa77jPvlsxM4WPqnDIM2qiK36up3SKkYwFjff6F
    2ni/ry8vrwXCX3sGZ1hbIHlK0O012HpA3ISeEswVZmX2X67naOvJXfY5v0hGPWqCADao+xVxrmx
    sZD4IWnKl1UaZzI5lhAzr8fw6utHwx1EZ/MSgsEki6tujcZfN+GUDRnmJGQSnPTXmsf7Q4DKreT
    Zk49cuyB3prV91S0x3DYjCUpSXrkVy1Ha5XicGD/q+ystuFsJnrrhbNXJbpSjM6sjo/aduAkZJl
    4FmOt0R7Q==\", \"exponent\": \"AQAB\", \"email\": \"example.user@example.com\",
    \"expireOn\": \"2015-04-14T01:37:19Z\"}
    

    Note que não deve haver novas linhas na string JSON.

  6. Adicione o objeto JSON aos metadados de instância. Defina os metadados da instância usando a chave de metadados windows-keys e o objeto JSON como o valor da chave.

    Para atualizar os metadados da instância na API, forneça uma impressão digital com a solicitação. Receba a impressão digital atual da instância enviando uma solicitação GET à instância:

    GET  https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-f/instances/test-windows-auth
    [..snip..]
    "metadata": {
    "kind": "compute#metadata",
    "fingerprint": "5sFotm8Ee0I=",
    "items": [
     {
     …
     }
    [..snip]..
    

    Em seguida, envie uma solicitação POST ao método setMetadata, fornecendo a impressão digital e o objeto JSON que você criou:

    POST https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-f/instances/test-windows-auth/setMetadata
    
    {
     "fingerprint": "5sFotm8Ee0I=",
     "items": [
      {
       "value": "{\"userName\": \"example-user\",  \"modulus\": \"wgsquN4IBNPqIUnu+h/5Za1kujb2YRhX1vCQVQAkBwnWigcCqOBVfRa5JoZfx6KIvEXjWqa77jPvlsxM4WPqnDIM2qiK36up3SKkYwFjff6F2ni/ry8vrwXCX3sGZ1hbIHlK0O012HpA3ISeEswVZmX2X67naOvJXfY5v0hGPWqCADao+xVxrmxsZD4IWnKl1UaZzI5lhAzr8fw6utHwx1EZ/MSgsEki6tujcZfN+GUDRnmJGQSnPTXmsf7Q4DKreTZk49cuyB3prV91S0x3DYjCUpSXrkVy1Ha5XicGD/q+ystuFsJnrrhbNXJbpSjM6sjo/aduAkZJl4FmOt0R7Q==\", \"exponent\": \"AQAB\", \"email\": \"user@example.com\", \"expireOn': '2015\"04-14T01:37:19Z\"}\n",
       "key": "windows-keys"
      } ]
    }
    

    Defina o nome da chave como windows-keys e o valor como uma ou mais strings JSON semelhantes à string acima. Separe as strings usando novas linhas. Ao adicionar várias entradas, respeite o limite de 32 KB para valor de metadados.

  7. Leia a saída da porta serial 4. No agente da instância, o valor de windows-keys será automaticamente usado e uma senha criptografada será criada. Para ler essa senha, consulte a porta serial 4. Na API, faça uma solicitação GET para o método getSerialPortOutput, transmitindo port=4 como um parâmetro de consulta:

    GET https://www.googleapis.com/compute/v1/projects/myproject/zones/us-central1-f/instances/test-windows-auth/serialPort?port=4
    
    {
     "kind": "compute#serialPortOutput",
     "selfLink": "https://www.googleapis.com/compute/v1/projects/myproject/zones/_/instances/test-api-auth/serialPort",
     "contents": "{\"ready\":true,\"version\":\"Microsoft Windows NT 6.1.7601 Service Pack 1\"}\n{\"encryptedPassword\":\"uiHDEhxyvj6lF5GalH
     h9TsMZb4bG6Y9qGmFb9S3XI29yvVsDCLdp4IbUg21MncHcaxP0rFu0kyjxlEXDs8y4L1KOhy6iyB42Lh+vZ4XIMjmvU4rZrjsBZ5TxQo9hL0lBW7o3FRM\\/UIXCeRk39ObUl2A
     jDmQ0mcw1byJI5v9KVJnNMaHdRCy\\/kvN6bx3qqjIhIMu0JExp4UVkAX2Mxb9b+c4o2DiZF5pY6ZfbuEmjSbvGRJXyswkOJ4jTZl+7e6+SZfEal8HJyRfZKiqTjrz+DLjYSlXr
     fIRqlvKeAFGOJq6IRojNWiTOOh8Zorc0iHDTIkf+MY0scfbBUo5m30Bf4w==\",\"exponent\":\"AQAB\",\"modulus\":\"0tiKdO2JmBHss26jnrSAwb583KG\\/ZIw5Jw
     wMPXrCVsFAPwY1OV3RlT1Hp4Xvpibr7rvJbOC+f\\/Gd0cBrK5pccQfccB+OHKpbBof473zEfRbdtFwPn10RfAFj\\/xikW0r\\/XxgG\\/c8tz9bmALBStGqmwOVOLRHxjwgtG
     u4poeuwmFfG6TuwgCadxpllW74mviFd4LZVSuCSni5YJnBM2HSJ8NP6g1fqI17KDXt2XO\\/7kSItubmMk+HGEXdH4qiugHYewaIf1o4XSQROC8xlRl7t\\/RaD4U58hKYkVwg0
     Ir7WzYzAVpG2UR4Co\\/GDG9Hct7HOYekDqVQ+sSZbwzajnVunkw==\",\"passwordFound\":true,\"userName\":\"example-user\"}\n"
    }
    

    Na saída da porta serial pode haver várias respostas separadas por novas linhas. Para encontrar a resposta correta, verifique se o módulo que você passou corresponde à saída da porta serial. Cada resposta é uma string codificada em JSON com os seguintes campos:

    • userName: o nome de usuário que foi transmitido para a instância.
    • passwordFound: um valor booleano que indica se a senha foi gerada com êxito.
    • encryptedPassword: uma senha criptografada codificada no formato base64.
    • modulus: o módulo que foi passado anteriormente.
    • exponent: o expoente que foi transmitido anteriormente.

    Para mais informações sobre retenção de saída da porta serial, consulte Como visualizar a saída da porta serial.

  8. Descriptografe a senha. Use a chave privada criada anteriormente para descriptografar a senha. Para isso, use o Optimal Asymmetric Encryption Padding (OAEP). No OpenSSL, o comando usado para descriptografar dados de entrada é:

    $ openssl rsautl -decrypt -inkey private_key -oaep
    

    Para descriptografar a senha acima, forneça o valor encryptedPassword. Lembre-se de antes remover os caracteres de escape \\ da string. Se você não fizer isso, haverá falha na descriptografia:

    $ echo 'uiHDEhxyvj6lF5GalHh9TsMZb4bG6Y9qGmFb9S3XI291MncHcaxP0rFu0kyjxlEXDs8y4L1KOhy6iyB42Lh+vZ4XIMjmvU4rZrjsBZ5Tx
    Qo9hL0lBW7o3FRM/UIXCeRk39ObUl2AjDmQ0mcw1byJI5v9KVJnNMaHdRCy/kvN6bx3qqjIhIMu0JExp4UVkAX2Mxb9b+c4o2DiZF5pY6ZfbuEmjS
    bvGRJXyswkOJ4jTZl+7e6+SZfEal8HJyRfZKiqTjrz+DLjYSlXrfIRqlvKeAFGOJq6IRojNWiTOOh8Zorc0iHDTIkf+MY0scfbBUo5m30Bf4w==' |
    base64 -d | openssl rsautl -decrypt -inkey private_key -oaep
    

    Use esse comando para imprimir a senha descriptografada:

    dDkJ_3]*QYS-#>X
    

    O nome de usuário e a senha desta conta seriam:

    username: example-user
    password: dDkJ_3]*QYS-#>X
    
  9. Jogue fora as chaves. Ao contrário das chaves SSH, as chaves usadas para recuperar/redefinir senhas do Windows são temporárias. Não reutilize pares de chaves públicas/privadas, porque o resultado pode não ser o esperado. Se a chave estiver salva no disco, exclua os arquivos no final do processo. Ou melhor, se possível, mantenha a chave na memória e descarte-a quando o processo for concluído.

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