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>

Author: rsc

chacha20/chacha_generic.go

@@ -12,7 +12,7 @@ import (
 	"errors"
 	"math/bits"
 
-	"golang.org/x/crypto/internal/subtle"
+	"golang.org/x/crypto/internal/alias"
 )
 
 const (
@@ -189,7 +189,7 @@ func (s *Cipher) XORKeyStream(dst, src []byte) {
 		panic("chacha20: output smaller than input")
 	}
 	dst = dst[:len(src)]
-	if subtle.InexactOverlap(dst, src) {
+	if alias.InexactOverlap(dst, src) {
 		panic("chacha20: invalid buffer overlap")
 	}
 

chacha20poly1305/chacha20poly1305_amd64.go

@@ -10,7 +10,7 @@ package chacha20poly1305
 import (
 	"encoding/binary"
 
-	"golang.org/x/crypto/internal/subtle"
+	"golang.org/x/crypto/internal/alias"
 	"golang.org/x/sys/cpu"
 )
 
@@ -56,7 +56,7 @@ func (c *chacha20poly1305) seal(dst, nonce, plaintext, additionalData []byte) []
 	setupState(&state, &c.key, nonce)
 
 	ret, out := sliceForAppend(dst, len(plaintext)+16)
-	if subtle.InexactOverlap(out, plaintext) {
+	if alias.InexactOverlap(out, plaintext) {
 		panic("chacha20poly1305: invalid buffer overlap")
 	}
 	chacha20Poly1305Seal(out[:], state[:], plaintext, additionalData)
@@ -73,7 +73,7 @@ func (c *chacha20poly1305) open(dst, nonce, ciphertext, additionalData []byte) (
 
 	ciphertext = ciphertext[:len(ciphertext)-16]
 	ret, out := sliceForAppend(dst, len(ciphertext))
-	if subtle.InexactOverlap(out, ciphertext) {
+	if alias.InexactOverlap(out, ciphertext) {
 		panic("chacha20poly1305: invalid buffer overlap")
 	}
 	if !chacha20Poly1305Open(out, state[:], ciphertext, additionalData) {

chacha20poly1305/chacha20poly1305_generic.go

@@ -8,8 +8,8 @@ import (
 	"encoding/binary"
 
 	"golang.org/x/crypto/chacha20"
+	"golang.org/x/crypto/internal/alias"
 	"golang.org/x/crypto/internal/poly1305"
-	"golang.org/x/crypto/internal/subtle"
 )
 
 func writeWithPadding(p *poly1305.MAC, b []byte) {
@@ -30,7 +30,7 @@ func writeUint64(p *poly1305.MAC, n int) {
 func (c *chacha20poly1305) sealGeneric(dst, nonce, plaintext, additionalData []byte) []byte {
 	ret, out := sliceForAppend(dst, len(plaintext)+poly1305.TagSize)
 	ciphertext, tag := out[:len(plaintext)], out[len(plaintext):]
-	if subtle.InexactOverlap(out, plaintext) {
+	if alias.InexactOverlap(out, plaintext) {
 		panic("chacha20poly1305: invalid buffer overlap")
 	}
 
@@ -66,7 +66,7 @@ func (c *chacha20poly1305) openGeneric(dst, nonce, ciphertext, additionalData []
 	writeUint64(p, len(ciphertext))
 
 	ret, out := sliceForAppend(dst, len(ciphertext))
-	if subtle.InexactOverlap(out, ciphertext) {
+	if alias.InexactOverlap(out, ciphertext) {
 		panic("chacha20poly1305: invalid buffer overlap")
 	}
 	if !p.Verify(tag) {

internal/subtle/aliasing.go internal/alias/alias.go

@@ -5,9 +5,8 @@
 //go:build !purego
 // +build !purego
 
-// Package subtle implements functions that are often useful in cryptographic
-// code but require careful thought to use correctly.
-package subtle // import "golang.org/x/crypto/internal/subtle"
+// Package alias implements memory aliasing tests.
+package alias
 
 import "unsafe"
 

internal/subtle/aliasing_purego.go internal/alias/alias_purego.go

@@ -5,9 +5,8 @@
 //go:build purego
 // +build purego
 
-// Package subtle implements functions that are often useful in cryptographic
-// code but require careful thought to use correctly.
-package subtle // import "golang.org/x/crypto/internal/subtle"
+// Package alias implements memory aliasing tests.
+package alias
 
 // This is the Google App Engine standard variant based on reflect
 // because the unsafe package and cgo are disallowed.

internal/subtle/aliasing_test.go internal/alias/alias_test.go

@@ -2,13 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package subtle_test
+package alias
 
-import (
-	"testing"
-
-	"golang.org/x/crypto/internal/subtle"
-)
+import "testing"
 
 var a, b [100]byte
 
@@ -32,11 +28,11 @@ var aliasingTests = []struct {
 }
 
 func testAliasing(t *testing.T, i int, x, y []byte, anyOverlap, inexactOverlap bool) {
-	any := subtle.AnyOverlap(x, y)
+	any := AnyOverlap(x, y)
 	if any != anyOverlap {
 		t.Errorf("%d: wrong AnyOverlap result, expected %v, got %v", i, anyOverlap, any)
 	}
-	inexact := subtle.InexactOverlap(x, y)
+	inexact := InexactOverlap(x, y)
 	if inexact != inexactOverlap {
 		t.Errorf("%d: wrong InexactOverlap result, expected %v, got %v", i, inexactOverlap, any)
 	}

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:])

salsa20/salsa20.go

@@ -24,7 +24,7 @@ package salsa20 // import "golang.org/x/crypto/salsa20"
 // TODO(agl): implement XORKeyStream12 and XORKeyStream8 - the reduced round variants of Salsa20.
 
 import (
-	"golang.org/x/crypto/internal/subtle"
+	"golang.org/x/crypto/internal/alias"
 	"golang.org/x/crypto/salsa20/salsa"
 )
 
@@ -35,7 +35,7 @@ func XORKeyStream(out, in []byte, nonce []byte, key *[32]byte) {
 	if len(out) < len(in) {
 		panic("salsa20: output smaller than input")
 	}
-	if subtle.InexactOverlap(out[:len(in)], in) {
+	if alias.InexactOverlap(out[:len(in)], in) {
 		panic("salsa20: invalid buffer overlap")
 	}
 

xts/xts.go

@@ -29,7 +29,7 @@ import (
 	"errors"
 	"sync"
 
-	"golang.org/x/crypto/internal/subtle"
+	"golang.org/x/crypto/internal/alias"
 )
 
 // Cipher contains an expanded key structure. It is safe for concurrent use if
@@ -75,7 +75,7 @@ func (c *Cipher) Encrypt(ciphertext, plaintext []byte, sectorNum uint64) {
 	if len(plaintext)%blockSize != 0 {
 		panic("xts: plaintext is not a multiple of the block size")
 	}
-	if subtle.InexactOverlap(ciphertext[:len(plaintext)], plaintext) {
+	if alias.InexactOverlap(ciphertext[:len(plaintext)], plaintext) {
 		panic("xts: invalid buffer overlap")
 	}
 
@@ -114,7 +114,7 @@ func (c *Cipher) Decrypt(plaintext, ciphertext []byte, sectorNum uint64) {
 	if len(ciphertext)%blockSize != 0 {
 		panic("xts: ciphertext is not a multiple of the block size")
 	}
-	if subtle.InexactOverlap(plaintext[:len(ciphertext)], ciphertext) {
+	if alias.InexactOverlap(plaintext[:len(ciphertext)], ciphertext) {
 		panic("xts: invalid buffer overlap")
 	}