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-rw-r--r--cryptfs/kdf.go38
1 files changed, 38 insertions, 0 deletions
diff --git a/cryptfs/kdf.go b/cryptfs/kdf.go
new file mode 100644
index 0000000..275c72e
--- /dev/null
+++ b/cryptfs/kdf.go
@@ -0,0 +1,38 @@
+package cryptfs
+
+import (
+ "fmt"
+ "golang.org/x/crypto/scrypt"
+)
+
+const (
+ // 1 << 16 uses 64MB of memory,
+ // takes 4 seconds on my Atom Z3735F netbook
+ SCRYPT_DEFAULT_N = 1 << 16
+)
+
+type scryptKdf struct {
+ Salt []byte
+ N int
+ R int
+ P int
+ KeyLen int
+}
+
+func NewScryptKdf() scryptKdf {
+ var s scryptKdf
+ s.Salt = RandBytes(KEY_LEN)
+ s.N = SCRYPT_DEFAULT_N
+ s.R = 8 // Always 8
+ s.P = 1 // Always 1
+ s.KeyLen = KEY_LEN
+ return s
+}
+
+func (s *scryptKdf) DeriveKey(pw string) []byte {
+ k, err := scrypt.Key([]byte(pw), s.Salt, s.N, s.R, s.P, s.KeyLen)
+ if err != nil {
+ panic(fmt.Sprintf("DeriveKey failed: %s", err.Error()))
+ }
+ return k
+}