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|
package sym
import (
"crypto/rand"
"encoding/binary"
"errors"
"flag"
"fmt"
"io"
"os"
"strings"
"roseh.moe/pkg/wordlist"
)
type encryptFlags struct {
generatePassword bool
password string
force bool
}
func (f *encryptFlags) RegisterFlags(fs *flag.FlagSet) {
fs.BoolVar(&f.generatePassword, "g", false, "generate a secure password automatically (password will be printed to stderr)")
fs.StringVar(&f.password, "p", "", "use the specified password; if not provided, enc will prompt for a password")
fs.BoolVar(&f.force, "f", false, "overwrite output files even if they already exist")
}
type EncryptOptions struct {
encryptFlags
iterations int
passwordIn func() (string, error)
passwordOut io.Writer
stdin io.Reader
stdout io.Writer
}
var DefaultEncryptOptions = EncryptOptions{
iterations: defaultPBKDF2Iters,
passwordIn: termReadPassword,
passwordOut: os.Stderr,
stdin: os.Stdin,
stdout: os.Stdout,
}
func (o *EncryptOptions) encrypt(w io.Writer, r io.Reader, password string) error {
if _, err := io.WriteString(w, magic); err != nil {
return err
}
header := &fileMetadata{
Version: 0,
HashMetadata: hashMetadata{
PasswordHashType: pwHashPBKDF2_HMAC_SHA256,
Iterations: int32(o.iterations),
SaltSize: defaultSaltSize,
},
EncryptionMetadata: encryptionMetadata{
EncryptionType: encryptionAlgAES256_GCM,
SegmentSize: defaultSegmentSize,
},
}
if err := binary.Write(w, binary.BigEndian, header); err != nil {
return err
}
writer := header.EncryptionMetadata.newEncryptingWriter(w, password, &header.HashMetadata)
if _, err := io.Copy(writer, r); err != nil {
return err
}
return writer.Close()
}
func (o *EncryptOptions) encryptFile(fileName string, password string) (err error) {
f, err := os.Open(fileName)
if err != nil {
return err
}
defer f.Close()
fileOpts := os.O_CREATE | os.O_WRONLY
if o.force {
fileOpts |= os.O_TRUNC
} else {
fileOpts |= os.O_EXCL
}
fOut, err := os.OpenFile(fileName+".enc", fileOpts, 0644)
if err != nil {
if errors.Is(err, os.ErrExist) {
return fmt.Errorf("output file %q exists (use -f to overwrite)", fileName+".enc")
}
return err
}
defer func() {
fOut.Close()
if err != nil {
os.Remove(fOut.Name())
}
}()
if err = o.encrypt(fOut, f, password); err != nil {
return fmt.Errorf("encrypt %q: %s", fileName, err)
}
return fOut.Close()
}
func (o *EncryptOptions) readPassword() (string, error) {
const maxAttempts = 3
for i := 1; i <= maxAttempts; i++ {
fmt.Fprint(os.Stderr, "Enter password")
if i > 1 {
fmt.Fprintf(os.Stderr, " (attempt %d/%d)", i, maxAttempts)
}
fmt.Fprint(os.Stderr, ": ")
password, err := o.passwordIn()
fmt.Fprintln(os.Stderr)
if err != nil {
return "", err
}
if password == "" {
fmt.Fprintln(os.Stderr, "Password cannot be empty")
continue
}
fmt.Fprint(os.Stderr, "Repeat password: ")
pwConfirm, err := o.passwordIn()
fmt.Fprintln(os.Stderr)
if err != nil {
return "", err
}
if pwConfirm != password {
fmt.Fprintln(os.Stderr, "Passwords do not match")
continue
}
return password, nil
}
return "", fmt.Errorf("too many attempts")
}
func (o *EncryptOptions) Run(args ...string) error {
if o.generatePassword && o.password != "" {
return fmt.Errorf("-g and -p cannot be used together")
}
if len(args) == 0 && !o.generatePassword && o.password == "" {
return fmt.Errorf("must use -g or -p when reading from stdin")
}
var password string
if o.password != "" {
password = o.password
} else if o.generatePassword {
const nWords = 10
buf := make([]byte, 2*nWords)
rand.Read(buf)
words := make([]string, nWords)
for i := range words {
words[i] = wordlist.Words[binary.NativeEndian.Uint16(buf[2*i:])&0x1fff]
}
password = strings.Join(words, " ")
fmt.Fprint(os.Stderr, "Your password: ")
fmt.Fprint(o.passwordOut, password)
fmt.Fprintln(os.Stderr)
} else {
var err error
if password, err = o.readPassword(); err != nil {
return err
}
}
if len(args) == 0 {
return o.encrypt(o.stdout, o.stdin, password)
}
for _, fileName := range args {
if err := o.encryptFile(fileName, password); err != nil {
return err
}
}
return nil
}
|
