cwtch/peer/storage.go

package peer

import (
	"crypto/rand"
	"database/sql"
	"fmt"
	"git.openprivacy.ca/openprivacy/log"
	"golang.org/x/crypto/pbkdf2"
	"golang.org/x/crypto/sha3"
	"io"
	"io/ioutil"
	"os"
	"path"
	"path/filepath"
)

const versionFile = "VERSION"
const version = "2"
const saltFile = "SALT"

// CreateKeySalt derives a key and salt from a password: returns key, salt, err
func CreateKeySalt(password string) ([32]byte, [128]byte, error) {
	var salt [128]byte
	if _, err := io.ReadFull(rand.Reader, salt[:]); err != nil {
		log.Errorf("Cannot read from random: %v\n", err)
		return [32]byte{}, salt, err
	}
	dk := pbkdf2.Key([]byte(password), salt[:], 4096, 32, sha3.New512)

	var dkr [32]byte
	copy(dkr[:], dk)
	return dkr, salt, nil
}

// createKey derives a key from a password and salt
func createKey(password string, salt []byte) [32]byte {
	dk := pbkdf2.Key([]byte(password), salt, 4096, 32, sha3.New512)

	var dkr [32]byte
	copy(dkr[:], dk)
	return dkr
}

func initV2Directory(directory, password string) ([32]byte, [128]byte, error) {
	os.Mkdir(directory, 0700)

	key, salt, err := CreateKeySalt(password)
	if err != nil {
		log.Errorf("Could not create key for profile store from password: %v\n", err)
		return [32]byte{}, [128]byte{}, err
	}

	if err = ioutil.WriteFile(path.Join(directory, versionFile), []byte(version), 0600); err != nil {
		log.Errorf("Could not write version file: %v", err)
		return [32]byte{}, [128]byte{}, err
	}

	if err = ioutil.WriteFile(path.Join(directory, saltFile), salt[:], 0600); err != nil {
		log.Errorf("Could not write salt file: %v", err)
		return [32]byte{}, [128]byte{}, err
	}

	return key, salt, nil
}

func openEncryptedDatabase(profileDirectory string, password string) (*sql.DB, error) {
	salt, err := ioutil.ReadFile(path.Join(profileDirectory, saltFile))
	if err != nil {
		return nil, err
	}

	key := createKey(password, salt)
	dbPath := filepath.Join(profileDirectory, "db")
	dbname := fmt.Sprintf("%v?_pragma_key=x'%x'&_pragma_cipher_page_size=8192", dbPath, key)
	db, err := sql.Open("sqlite3", dbname)
	if err != nil {
		log.Errorf("could not open encrypted database", err)
		return nil, err
	}
	return db, nil
}

// CreateEncryptedStorePeer creates a *new* Cwtch Profile backed by an encrypted datastore
func CreateEncryptedStorePeer(profileDirectory string, name string, password string) (CwtchPeer, error) {
	log.Debugf("Initializing Encrypted Storage Directory")
	_, _, err := initV2Directory(profileDirectory, password)
	if err != nil {
		return nil, err
	}

	log.Debugf("Opening Encrypted Database")
	db, err := openEncryptedDatabase(profileDirectory, password)
	if db == nil || err != nil {
		return nil, fmt.Errorf("unable to open encrypted database: error: %v", err)
	}

	log.Debugf("Initializing Database")
	err = initializeDatabase(db)

	if err != nil {
		db.Close()
		return nil, err
	}

	log.Debugf("Creating Cwtch Profile Backed By Encrypted Database")

	cps, err := NewCwtchProfileStorage(db)
	if err != nil {
		db.Close()
		return nil, err
	}

	return NewProfileWithEncryptedStorage(name, cps), nil
}

// CreateEncryptedStore creates a encrypted datastore
func CreateEncryptedStore(profileDirectory string, password string) (*CwtchProfileStorage, error) {
	log.Debugf("Initializing Encrypted Storage Directory")
	_, _, err := initV2Directory(profileDirectory, password)
	if err != nil {
		return nil, err
	}

	log.Debugf("Opening Encrypted Database")
	db, err := openEncryptedDatabase(profileDirectory, password)
	if db == nil || err != nil {
		return nil, fmt.Errorf("unable to open encrypted database: error: %v", err)
	}

	log.Debugf("Initializing Database")
	err = initializeDatabase(db)

	if err != nil {
		db.Close()
		return nil, err
	}

	log.Debugf("Creating Cwtch Profile Backed By Encrypted Database")

	cps, err := NewCwtchProfileStorage(db)
	if err != nil {
		db.Close()
		return nil, err
	}

	return cps, nil
}

// FromEncryptedDatabase constructs a Cwtch Profile from an existing Encrypted Database
func FromEncryptedDatabase(profileDirectory string, password string) (CwtchPeer, error) {
	log.Debugf("Loading Encrypted Profile")
	db, err := openEncryptedDatabase(profileDirectory, password)
	if db == nil || err != nil {
		return nil, fmt.Errorf("unable to open encrypted database: error: %v", err)
	}

	log.Debugf("Initializing Profile from Encrypted Storage")
	cps, err := NewCwtchProfileStorage(db)
	if err != nil {
		db.Close()
		return nil, err
	}
	return FromEncryptedStorage(cps), nil
}