cryptocore: rename "BackendTypeEnum" -> "AEADTypeEnum"

There are two independent backends, one for name encryption,
the other one, AEAD, for file content.

"BackendTypeEnum" only applies to AEAD (file content), so make that
clear in the name.

internal/cryptocore/cryptocore.go

@@ -15,8 +15,8 @@ import (
 	"github.com/rfjakob/gocryptfs/internal/stupidgcm"
 )
 
-// BackendTypeEnum indicates the type of backend in use.
-type BackendTypeEnum int
+// BackendTypeEnum indicates the type of AEAD backend in use.
+type AEADTypeEnum int
 
 const (
 	// KeyLen is the cipher key length in bytes.  32 for AES-256.
@@ -26,11 +26,11 @@ const (
 
 	_ = iota // Skip zero
 	// BackendOpenSSL specifies the OpenSSL backend.
-	BackendOpenSSL BackendTypeEnum = iota
+	BackendOpenSSL AEADTypeEnum = iota
 	// BackendGoGCM specifies the Go based GCM backend.
-	BackendGoGCM BackendTypeEnum = iota
+	BackendGoGCM AEADTypeEnum = iota
 	// BackendAESSIV specifies an AESSIV backend.
-	BackendAESSIV BackendTypeEnum = iota
+	BackendAESSIV AEADTypeEnum = iota
 )
 
 // CryptoCore is the low level crypto implementation.
@@ -40,7 +40,7 @@ type CryptoCore struct {
 	// GCM or AES-SIV. This is used for content encryption.
 	AEADCipher cipher.AEAD
 	// Which backend is behind AEADCipher?
-	AEADBackend BackendTypeEnum
+	AEADBackend AEADTypeEnum
 	// GCM needs unique IVs (nonces)
 	IVGenerator *nonceGenerator
 	IVLen       int
@@ -51,7 +51,7 @@ type CryptoCore struct {
 // Even though the "GCMIV128" feature flag is now mandatory, we must still
 // support 96-bit IVs here because they are used for encrypting the master
 // key in gocryptfs.conf.
-func New(key []byte, backend BackendTypeEnum, IVBitLen int) *CryptoCore {
+func New(key []byte, aeadType AEADTypeEnum, IVBitLen int) *CryptoCore {
 	if len(key) != KeyLen {
 		log.Panic(fmt.Sprintf("Unsupported key length %d", len(key)))
 	}
@@ -67,7 +67,7 @@ func New(key []byte, backend BackendTypeEnum, IVBitLen int) *CryptoCore {
 	emeCipher := eme.New(blockCipher)
 
 	var aeadCipher cipher.AEAD
-	switch backend {
+	switch aeadType {
 	case BackendOpenSSL:
 		if IVLen != 16 {
 			log.Panic("stupidgcm only supports 128-bit IVs")
@@ -95,7 +95,7 @@ func New(key []byte, backend BackendTypeEnum, IVBitLen int) *CryptoCore {
 	return &CryptoCore{
 		EMECipher:   emeCipher,
 		AEADCipher:  aeadCipher,
-		AEADBackend: backend,
+		AEADBackend: aeadType,
 		IVGenerator: &nonceGenerator{nonceLen: IVLen},
 		IVLen:       IVLen,
 	}

internal/fusefrontend/args.go

@@ -8,7 +8,7 @@ import (
 type Args struct {
 	Masterkey      []byte
 	Cipherdir      string
-	CryptoBackend  cryptocore.BackendTypeEnum
+	CryptoBackend  cryptocore.AEADTypeEnum
 	PlaintextNames bool
 	LongNames      bool
 	// Should we chown a file after it has been created?