Wrap NewGCMWithNonceSize() to enable compilation on Go 1.4

.travis.yml

@@ -1,6 +1,7 @@
 language: go
 
 go:
+  - 1.4.3
   - 1.5.1
   - tip
 

cryptfs/gcm_go14.go

@@ -0,0 +1,21 @@
+// +build !go1.5
+
+package cryptfs
+
+import (
+	"fmt"
+	"crypto/cipher"
+)
+
+// goGCMWrapper - This wrapper makes sure gocryptfs can be compiled on Go
+// versions 1.4 and lower that lack NewGCMWithNonceSize().
+// 128 bit GCM IVs will not work when using built-in Go crypto, obviously, when
+// compiled on 1.4.
+func goGCMWrapper(bc cipher.Block, nonceSize int) (cipher.AEAD, error){
+	if nonceSize != 12 {
+		Warn.Printf("128 bit GCM IVs are not supported by Go 1.4 and lower.\n")
+		Warn.Printf("Please use openssl crypto or recompile using a newer Go runtime.\n")
+		return nil, fmt.Errorf("128 bit GCM IVs are not supported by Go 1.4 and lower")
+	}
+	return cipher.NewGCM(bc)
+}

cryptfs/gcm_go15.go

@@ -0,0 +1,15 @@
+// +build go1.5
+
+package cryptfs
+
+import (
+	"crypto/cipher"
+)
+
+// goGCMWrapper - This wrapper makes sure gocryptfs can be compiled on Go
+// versions 1.4 and lower that lack NewGCMWithNonceSize().
+// 128 bit GCM IVs will not work when using built-in Go crypto, obviously, when
+// compiled on 1.4.
+func goGCMWrapper(bc cipher.Block, nonceSize int) (cipher.AEAD, error){
+	return cipher.NewGCMWithNonceSize(bc, nonceSize)
+}

cryptfs/openssl_test.go

@@ -10,7 +10,6 @@ package cryptfs
 
 import (
 	"crypto/aes"
-	"crypto/cipher"
 	"testing"
 )
 
@@ -20,7 +19,7 @@ func benchmarkGoEnc(b *testing.B, plaintext []byte, key []byte, nonce []byte) (c
 	if err != nil {
 		b.Fatal(err)
 	}
-	aesgcm, err := cipher.NewGCMWithNonceSize(aes, len(nonce))
+	aesgcm, err := goGCMWrapper(aes, len(nonce))
 	if err != nil {
 		b.Fatal(err)
 	}