GetMasterKey

[0sm1les]

I have a question about the chromium Get Master key function. When building and executing HackBrowserData the function works as expected but when I create a new function only to get the master key value it defaults to the peanuts value. My question is what is the setup required for this function to work? below is my code.

package main

import (
	"crypto/hmac"
	"crypto/sha1"
	"fmt"
	"hash"
	"log/slog"

	"github.com/godbus/dbus/v5"
	keyring "github.com/ppacher/go-dbus-keyring"
)

type Chromium struct {
	name        string
	storage     string
	profilePath string
	masterKey   []byte
}

func main() {
	var chromium Chromium
	chromium.GetMasterKey()
}

func (c *Chromium) GetMasterKey() ([]byte, error) {
	// what is d-bus @https://dbus.freedesktop.org/
	// don't need chromium key file for Linux
	//defer os.Remove(types.ChromiumKey.TempFilename())

	conn, err := dbus.SessionBus()
	if err != nil {
		return nil, err
	}
	svc, err := keyring.GetSecretService(conn)
	if err != nil {
		return nil, err
	}
	session, err := svc.OpenSession()
	if err != nil {
		return nil, err
	}
	defer func() {
		if err := session.Close(); err != nil {
			slog.Error("close dbus session error", "err", err.Error())
		}
	}()
	collections, err := svc.GetAllCollections()
	if err != nil {
		return nil, err
	}
	var secret []byte
	for _, col := range collections {
		items, err := col.GetAllItems()
		if err != nil {
			return nil, err
		}
		for _, i := range items {
			label, err := i.GetLabel()
			if err != nil {
				slog.Warn("get label from dbus", "err", err.Error())
				continue
			}
			if label == c.storage {
				se, err := i.GetSecret(session.Path())
				if err != nil {
					return nil, fmt.Errorf("get storage from dbus: %w", err)
				}
				secret = se.Value
			}
		}
	}

	if len(secret) == 0 {
		// set default secret @https://source.chromium.org/chromium/chromium/src/+/main:components/os_crypt/os_crypt_linux.cc;l=100
		secret = []byte("peanuts")
	}
	salt := []byte("saltysalt")
	// @https://source.chromium.org/chromium/chromium/src/+/master:components/os_crypt/os_crypt_linux.cc
	fmt.Println(secret, salt, 1, 16, sha1.New())
	key := PBKDF2Key(secret, salt, 1, 16, sha1.New)
	c.masterKey = key
	slog.Info("get master key success", "browser", c.name)
	return key, nil
}

func PBKDF2Key(password, salt []byte, iter, keyLen int, h func() hash.Hash) []byte {
	prf := hmac.New(h, password)
	hashLen := prf.Size()
	numBlocks := (keyLen + hashLen - 1) / hashLen

	var buf [4]byte
	dk := make([]byte, 0, numBlocks*hashLen)
	u := make([]byte, hashLen)
	for block := 1; block <= numBlocks; block++ {
		// N.B.: || means concatenation, ^ means XOR
		// for each block T_i = U_1 ^ U_2 ^ ... ^ U_iter
		// U_1 = PRF(password, salt || uint(i))
		prf.Reset()
		prf.Write(salt)
		buf[0] = byte(block >> 24)
		buf[1] = byte(block >> 16)
		buf[2] = byte(block >> 8)
		buf[3] = byte(block)
		prf.Write(buf[:4])
		dk = prf.Sum(dk)
		t := dk[len(dk)-hashLen:]
		copy(u, t)

		for n := 2; n <= iter; n++ {
			prf.Reset()
			prf.Write(u)
			u = u[:0]
			u = prf.Sum(u)
			for x := range u {
				t[x] ^= u[x]
			}
		}
	}
	return dk[:keyLen]
}

[0sm1les]

Its because c.storage was not set