lockbox

commit a3163291d014bea9da99d86b83db224d9825d122
parent 88f8088146870f79d1b4fc31bb2be7e910bff8f9
Author: Sean Enck <sean@ttypty.com>
Date:   Sun, 18 Sep 2022 12:36:10 -0400

all forms should pad

Diffstat:
M
internal/encrypt/core.go
 | 
21
+++++++++++++++++++--
M
internal/encrypt/secretbox.go
 | 
19
++-----------------

2 files changed, 21 insertions(+), 19 deletions(-)
diff --git a/internal/encrypt/core.go b/internal/encrypt/core.go
@@ -2,8 +2,10 @@
 package encrypt
 
 import (
+	"crypto/rand"
 	"crypto/sha512"
 	"errors"
+	"io"
 	random "math/rand"
 	"os"
 	"time"
@@ -15,6 +17,7 @@ import (
 const (
 	keyLength            = 32
 	algorithmBaseVersion = 0
+	padLength            = 256
 )
 
 const (
@@ -139,11 +142,20 @@ func (l Lockbox) Encrypt(datum []byte) error {
 	if len(data) == 0 {
 		return errors.New("no data given")
 	}
+	padTo := random.Intn(padLength)
+	var padding [padLength]byte
+	if _, err := io.ReadFull(rand.Reader, padding[:]); err != nil {
+		return err
+	}
 	box := newAlgorithm(l.algo)
 	if box == nil {
 		return errors.New("unknown algorithm detected")
 	}
-	b, err := box.encrypt(l.secret[:], data)
+	var write []byte
+	write = append(write, byte(padTo))
+	write = append(write, padding[0:padTo]...)
+	write = append(write, data...)
+	b, err := box.encrypt(l.secret[:], write)
 	if err != nil {
 		return err
 	}
@@ -175,5 +187,10 @@ func (l Lockbox) Decrypt() ([]byte, error) {
 	if len(data) <= box.dataSize() {
 		return nil, errors.New("data is invalid for decryption")
 	}
-	return box.decrypt(l.secret[:], data)
+	decrypted, err := box.decrypt(l.secret[:], data)
+	if err != nil {
+		return nil, err
+	}
+	padding := int(decrypted[0])
+	return decrypted[1+padding:], nil
 }
diff --git a/internal/encrypt/secretbox.go b/internal/encrypt/secretbox.go
@@ -4,7 +4,6 @@ import (
 	"crypto/rand"
 	"errors"
 	"io"
-	random "math/rand"
 
 	"golang.org/x/crypto/nacl/secretbox"
 )
@@ -16,7 +15,6 @@ type (
 
 const (
 	secretBoxAlgorithmNonceLength = 24
-	secretBoxAlgorithmPadLength   = 256
 	secretBoxAlgorithmSaltLength  = 16
 )
 
@@ -34,27 +32,15 @@ func (s secretBoxAlgorithm) version() algorithmVersions {
 
 func (s secretBoxAlgorithm) encrypt(encryptKey, data []byte) ([]byte, error) {
 	var nonce [secretBoxAlgorithmNonceLength]byte
-	padTo := random.Intn(secretBoxAlgorithmPadLength)
-	if _, err := io.ReadFull(rand.Reader, nonce[:]); err != nil {
-		return nil, err
-	}
-	var padding [secretBoxAlgorithmPadLength]byte
-	if _, err := io.ReadFull(rand.Reader, padding[:]); err != nil {
-		return nil, err
-	}
 	var salt [secretBoxAlgorithmSaltLength]byte
 	if _, err := io.ReadFull(rand.Reader, salt[:]); err != nil {
 		return nil, err
 	}
-	var write []byte
-	write = append(write, byte(padTo))
-	write = append(write, padding[0:padTo]...)
-	write = append(write, data...)
 	key, err := pad(salt[:], encryptKey[:])
 	if err != nil {
 		return nil, err
 	}
-	encrypted := secretbox.Seal(nonce[:], write, &nonce, &key)
+	encrypted := secretbox.Seal(nonce[:], data, &nonce, &key)
 	var persist []byte
 	persist = append(persist, salt[:]...)
 	persist = append(persist, encrypted...)
@@ -75,6 +61,5 @@ func (s secretBoxAlgorithm) decrypt(encryptKey, encrypted []byte) ([]byte, error
 		return nil, errors.New("decrypt not ok")
 	}
 
-	padding := int(decrypted[0])
-	return decrypted[1+padding:], nil
+	return decrypted, nil
 }