internal/subtle: rename to internal/alias

This avoids an import conflict in code that needs to import
crypto/subtle as well.

CL 424194 does the same for the main repo.

Change-Id: Ic54cb62bbfdcf5c2cb6f15ac47075ee1c41981ad
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/424175
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>

nacl/secretbox/secretbox.go

@@ -35,8 +35,8 @@ This package is interoperable with NaCl: https://nacl.cr.yp.to/secretbox.html.
 package secretbox // import "golang.org/x/crypto/nacl/secretbox"
 
 import (
+	"golang.org/x/crypto/internal/alias"
 	"golang.org/x/crypto/internal/poly1305"
-	"golang.org/x/crypto/internal/subtle"
 	"golang.org/x/crypto/salsa20/salsa"
 )
 
@@ -88,7 +88,7 @@ func Seal(out, message []byte, nonce *[24]byte, key *[32]byte) []byte {
 	copy(poly1305Key[:], firstBlock[:])
 
 	ret, out := sliceForAppend(out, len(message)+poly1305.TagSize)
-	if subtle.AnyOverlap(out, message) {
+	if alias.AnyOverlap(out, message) {
 		panic("nacl: invalid buffer overlap")
 	}
 
@@ -147,7 +147,7 @@ func Open(out, box []byte, nonce *[24]byte, key *[32]byte) ([]byte, bool) {
 	}
 
 	ret, out := sliceForAppend(out, len(box)-Overhead)
-	if subtle.AnyOverlap(out, box) {
+	if alias.AnyOverlap(out, box) {
 		panic("nacl: invalid buffer overlap")
 	}
 

nacl/sign/sign.go

@@ -24,7 +24,7 @@ import (
 	"io"
 
 	"golang.org/x/crypto/ed25519"
-	"golang.org/x/crypto/internal/subtle"
+	"golang.org/x/crypto/internal/alias"
 )
 
 // Overhead is the number of bytes of overhead when signing a message.
@@ -48,7 +48,7 @@ func GenerateKey(rand io.Reader) (publicKey *[32]byte, privateKey *[64]byte, err
 func Sign(out, message []byte, privateKey *[64]byte) []byte {
 	sig := ed25519.Sign(ed25519.PrivateKey((*privateKey)[:]), message)
 	ret, out := sliceForAppend(out, Overhead+len(message))
-	if subtle.AnyOverlap(out, message) {
+	if alias.AnyOverlap(out, message) {
 		panic("nacl: invalid buffer overlap")
 	}
 	copy(out, sig)
@@ -67,7 +67,7 @@ func Open(out, signedMessage []byte, publicKey *[32]byte) ([]byte, bool) {
 		return nil, false
 	}
 	ret, out := sliceForAppend(out, len(signedMessage)-Overhead)
-	if subtle.AnyOverlap(out, signedMessage) {
+	if alias.AnyOverlap(out, signedMessage) {
 		panic("nacl: invalid buffer overlap")
 	}
 	copy(out, signedMessage[Overhead:])