crypto/ed25519/internal/edwards25519: move to crypto/internal/edwards25519

This will allow us to use crypto/internal/edwards25519/field from
crypto/ecdh to implement X25519, dropping the dependency on
golang.org/x/crypto/curve25519.

For #52182

Change-Id: I3be9debc6e13bf06944b98668f34313a975914d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/402556
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>

src/crypto/ed25519/ed25519.go

@@ -15,7 +15,7 @@ package ed25519
 import (
 	"bytes"
 	"crypto"
-	"crypto/ed25519/internal/edwards25519"
+	"crypto/internal/edwards25519"
 	cryptorand "crypto/rand"
 	"crypto/sha512"
 	"errors"

src/crypto/internal/edwards25519/edwards25519.go

@@ -5,7 +5,7 @@
 package edwards25519
 
 import (
-	"crypto/ed25519/internal/edwards25519/field"
+	"crypto/internal/edwards25519/field"
 	"errors"
 )
 
@@ -147,9 +147,8 @@ func (v *Point) SetBytes(x []byte) (*Point, error) {
 	//      (*field.Element).SetBytes docs) and
 	//   2) the ones where the x-coordinate is zero and the sign bit is set.
 	//
-	// This is consistent with crypto/ed25519/internal/edwards25519. Read more
-	// at https://hdevalence.ca/blog/2020-10-04-its-25519am, specifically the
-	// "Canonical A, R" section.
+	// Read more at https://hdevalence.ca/blog/2020-10-04-its-25519am,
+	// specifically the "Canonical A, R" section.
 
 	y, err := new(field.Element).SetBytes(x)
 	if err != nil {

src/crypto/internal/edwards25519/edwards25519_test.go

@@ -5,7 +5,7 @@
 package edwards25519
 
 import (
-	"crypto/ed25519/internal/edwards25519/field"
+	"crypto/internal/edwards25519/field"
 	"encoding/hex"
 	"os"
 	"reflect"

src/crypto/internal/edwards25519/field/_asm/fe_amd64_asm.go

@@ -16,7 +16,7 @@ import (
 //go:generate go run . -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field
 
 func main() {
-	Package("crypto/ed25519/internal/edwards25519/field")
+	Package("crypto/internal/edwards25519/field")
 	ConstraintExpr("amd64,gc,!purego")
 	feMul()
 	feSquare()

src/go/build/deps_test.go

@@ -408,8 +408,8 @@ var depsRules = `
 	< crypto/internal/subtle
 	< crypto/internal/nistec/fiat
 	< crypto/internal/nistec
-	< crypto/ed25519/internal/edwards25519/field, golang.org/x/crypto/curve25519/internal/field
-	< crypto/ed25519/internal/edwards25519
+	< crypto/internal/edwards25519/field, golang.org/x/crypto/curve25519/internal/field
+	< crypto/internal/edwards25519
 	< crypto/cipher
 	< crypto/internal/boring
 	< crypto/boring