bcrypt: fix C compatibility code
The bcrypt implementation must append a zero byte to the user provided key
to be compatible to C implementations.
This will change the user provided key if the slice has enough capacity to
hold the extra zero byte.
This change always allocates a new slice for the C-compatible key.
Fixes golang/go#20425
Change-Id: I8dc4e840c29711daabdabe58d83643cc0103cedd
Reviewed-on: https://go-review.googlesource.com/43715
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/bcrypt/bcrypt.go b/bcrypt/bcrypt.go
index f8b807f..202fa8a 100644
--- a/bcrypt/bcrypt.go
+++ b/bcrypt/bcrypt.go
@@ -12,9 +12,10 @@
"crypto/subtle"
"errors"
"fmt"
- "golang.org/x/crypto/blowfish"
"io"
"strconv"
+
+ "golang.org/x/crypto/blowfish"
)
const (
@@ -205,7 +206,6 @@
}
func expensiveBlowfishSetup(key []byte, cost uint32, salt []byte) (*blowfish.Cipher, error) {
-
csalt, err := base64Decode(salt)
if err != nil {
return nil, err
@@ -213,7 +213,8 @@
// Bug compatibility with C bcrypt implementations. They use the trailing
// NULL in the key string during expansion.
- ckey := append(key, 0)
+ // We copy the key to prevent changing the underlying array.
+ ckey := append(key[:len(key):len(key)], 0)
c, err := blowfish.NewSaltedCipher(ckey, csalt)
if err != nil {
diff --git a/bcrypt/bcrypt_test.go b/bcrypt/bcrypt_test.go
index f08a6f5..aecf759 100644
--- a/bcrypt/bcrypt_test.go
+++ b/bcrypt/bcrypt_test.go
@@ -224,3 +224,20 @@
GenerateFromPassword(passwd, 10)
}
}
+
+// See Issue https://github.com/golang/go/issues/20425.
+func TestNoSideEffectsFromCompare(t *testing.T) {
+ source := []byte("passw0rd123456")
+ password := source[:len(source)-6]
+ token := source[len(source)-6:]
+ want := make([]byte, len(source))
+ copy(want, source)
+
+ wantHash := []byte("$2a$10$LK9XRuhNxHHCvjX3tdkRKei1QiCDUKrJRhZv7WWZPuQGRUM92rOUa")
+ _ = CompareHashAndPassword(wantHash, password)
+
+ got := bytes.Join([][]byte{password, token}, []byte(""))
+ if !bytes.Equal(got, want) {
+ t.Errorf("got=%q want=%q", got, want)
+ }
+}
