mirror of
https://github.com/restic/restic.git
synced 2024-08-23 04:40:46 +02:00
103 lines
2.6 KiB
Go
103 lines
2.6 KiB
Go
package crypto
|
|
|
|
import (
|
|
"crypto/rand"
|
|
"time"
|
|
|
|
"github.com/restic/restic/internal/errors"
|
|
|
|
sscrypt "github.com/elithrar/simple-scrypt"
|
|
"golang.org/x/crypto/scrypt"
|
|
)
|
|
|
|
const saltLength = 64
|
|
|
|
// Params are the default parameters used for the key derivation function KDF().
|
|
type Params struct {
|
|
N int
|
|
R int
|
|
P int
|
|
}
|
|
|
|
// DefaultKDFParams are the default parameters used for Calibrate and KDF().
|
|
var DefaultKDFParams = Params{
|
|
N: sscrypt.DefaultParams.N,
|
|
R: sscrypt.DefaultParams.R,
|
|
P: sscrypt.DefaultParams.P,
|
|
}
|
|
|
|
// Calibrate determines new KDF parameters for the current hardware.
|
|
func Calibrate(timeout time.Duration, memory int) (Params, error) {
|
|
defaultParams := sscrypt.Params{
|
|
N: DefaultKDFParams.N,
|
|
R: DefaultKDFParams.R,
|
|
P: DefaultKDFParams.P,
|
|
DKLen: sscrypt.DefaultParams.DKLen,
|
|
SaltLen: sscrypt.DefaultParams.SaltLen,
|
|
}
|
|
|
|
params, err := sscrypt.Calibrate(timeout, memory, defaultParams)
|
|
if err != nil {
|
|
return DefaultKDFParams, errors.Wrap(err, "scrypt.Calibrate")
|
|
}
|
|
|
|
return Params{
|
|
N: params.N,
|
|
R: params.R,
|
|
P: params.P,
|
|
}, nil
|
|
}
|
|
|
|
// KDF derives encryption and message authentication keys from the password
|
|
// using the supplied parameters N, R and P and the Salt.
|
|
func KDF(p Params, salt []byte, password string) (*Key, error) {
|
|
if len(salt) != saltLength {
|
|
return nil, errors.Errorf("scrypt() called with invalid salt bytes (len %d)", len(salt))
|
|
}
|
|
|
|
// make sure we have valid parameters
|
|
params := sscrypt.Params{
|
|
N: p.N,
|
|
R: p.R,
|
|
P: p.P,
|
|
DKLen: sscrypt.DefaultParams.DKLen,
|
|
SaltLen: len(salt),
|
|
}
|
|
|
|
if err := params.Check(); err != nil {
|
|
return nil, errors.Wrap(err, "Check")
|
|
}
|
|
|
|
derKeys := &Key{}
|
|
|
|
keybytes := macKeySize + aesKeySize
|
|
scryptKeys, err := scrypt.Key([]byte(password), salt, p.N, p.R, p.P, keybytes)
|
|
if err != nil {
|
|
return nil, errors.Wrap(err, "scrypt.Key")
|
|
}
|
|
|
|
if len(scryptKeys) != keybytes {
|
|
return nil, errors.Errorf("invalid numbers of bytes expanded from scrypt(): %d", len(scryptKeys))
|
|
}
|
|
|
|
// first 32 byte of scrypt output is the encryption key
|
|
copy(derKeys.EncryptionKey[:], scryptKeys[:aesKeySize])
|
|
|
|
// next 32 byte of scrypt output is the mac key, in the form k||r
|
|
macKeyFromSlice(&derKeys.MACKey, scryptKeys[aesKeySize:])
|
|
|
|
return derKeys, nil
|
|
}
|
|
|
|
// NewSalt returns new random salt bytes to use with KDF(). If NewSalt returns
|
|
// an error, this is a grave situation and the program must abort and terminate.
|
|
func NewSalt() ([]byte, error) {
|
|
buf := make([]byte, saltLength)
|
|
n, err := rand.Read(buf)
|
|
if n != saltLength || err != nil {
|
|
panic("unable to read enough random bytes for new salt")
|
|
}
|
|
|
|
return buf, nil
|
|
}
|