edwards25519: sync with upstream

Minor doc, names, go:build directive changes.

.github/workflows/test.yml

@@ -2,10 +2,16 @@ name: Go tests
 on: [push, pull_request]
 jobs:
   test:
+    name: Go ${{ matrix.go }}
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: [ '1.16', '1.x' ]
     steps:
       - uses: actions/setup-go@v2
-        with: { go-version: 1.x }
+        with: { go-version: "${{ matrix.go }}" }
       - uses: actions/checkout@v2
-      - run: go test -quickchecks 1
+      - run: go test -quickchecks 1 ./...
+      - run: go test -quickchecks 1 -tags purego ./...
       - run: GOARCH=arm64 go test -c
+      - run: GOARCH=arm go test -c

README.md

@@ -9,6 +9,6 @@ Read the docs at [pkg.go.dev/filippo.io/edwards25519](https://pkg.go.dev/filippo
 
 The code is originally derived from Adam Langley's internal implementation in the Go standard library, and includes George Tankersley's [performance improvements](https://golang.org/cl/71950). It was then further developed by Henry de Valence for use in ristretto255, and was finally [merged back into the Go standard library](https://golang.org/cl/276272) as of Go 1.17. It now tracks the upstream codebase and extends it with additional functionality.
 
-Most users don't need this package, and should instead use `crypto/ed25519` for signatures, `golang.org/x/crypto/curve25519` for Diffie-Hellman, or `github.com/gtank/ristretto255` for prime order group logic. However, for anyone currently using a fork of `crypto/ed25519/internal/edwards25519` or `github.com/agl/edwards25519`, this package should be a safer, faster, and more powerful alternative.
+Most users don't need this package, and should instead use `crypto/ed25519` for signatures, `golang.org/x/crypto/curve25519` for Diffie-Hellman, or `github.com/gtank/ristretto255` for prime order group logic. However, for anyone currently using a fork of `crypto/internal/edwards25519`/`crypto/ed25519/internal/edwards25519` or `github.com/agl/edwards25519`, this package should be a safer, faster, and more powerful alternative.
 
 Since this package is meant to curb proliferation of edwards25519 implementations in the Go ecosystem, it welcomes requests for new APIs or reviewable performance improvements.

doc.go

@@ -4,7 +4,7 @@
 
 // Package edwards25519 implements group logic for the twisted Edwards curve
 //
-//     -x^2 + y^2 = 1 + -(121665/121666)*x^2*y^2
+//	-x^2 + y^2 = 1 + -(121665/121666)*x^2*y^2
 //
 // This is better known as the Edwards curve equivalent to Curve25519, and is
 // the curve used by the Ed25519 signature scheme.
@@ -15,6 +15,6 @@
 //
 // However, developers who do need to interact with low-level edwards25519
 // operations can use this package, which is an extended version of
-// crypto/ed25519/internal/edwards25519 from the standard library repackaged as
+// crypto/internal/edwards25519 from the standard library repackaged as
 // an importable module.
 package edwards25519

edwards25519.go

@@ -148,9 +148,8 @@ 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
+	// Read more at https://hdevalence.ca/blog/2020-10-04-its-25519am,
-	// at https://hdevalence.ca/blog/2020-10-04-its-25519am, specifically the
+	// specifically the "Canonical A, R" section.
-	// "Canonical A, R" section.
 
 	y, err := new(field.Element).SetBytes(x)
 	if err != nil {

extra.go

@@ -5,7 +5,7 @@
 package edwards25519
 
 // This file contains additional functionality that is not included in the
-// upstream crypto/ed25519/internal/edwards25519 package.
+// upstream crypto/internal/edwards25519 package.
 
 import (
 	"errors"

field/_asm/go.mod

@@ -1,10 +1,17 @@
 module asm
 
-go 1.16
+go 1.18
 
 require (
 	filippo.io/edwards25519 v0.0.0
-	github.com/mmcloughlin/avo v0.2.0
+	github.com/mmcloughlin/avo v0.4.0
+)
+
+require (
+	golang.org/x/mod v0.4.2 // indirect
+	golang.org/x/sys v0.0.0-20211030160813-b3129d9d1021 // indirect
+	golang.org/x/tools v0.1.7 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 )
 
 replace filippo.io/edwards25519 v0.0.0 => ../..

field/_asm/go.sum

@@ -1,29 +1,30 @@
-github.com/mmcloughlin/avo v0.2.0 h1:6vhoSaKtxb6f4RiH+LK2qL6GSMpFzhEwJYTTSZNy09w=
+github.com/mmcloughlin/avo v0.4.0 h1:jeHDRktVD+578ULxWpQHkilor6pkdLF7u7EiTzDbfcU=
-github.com/mmcloughlin/avo v0.2.0/go.mod h1:5tidO2Z9Z7N6X7UMcGg+1KTj51O8OxYDCMHxCZTVpEA=
+github.com/mmcloughlin/avo v0.4.0/go.mod h1:RW9BfYA3TgO9uCdNrKU2h6J8cPD8ZLznvfgHAeszb1s=
-github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+github.com/yuin/goldmark v1.4.0/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
-golang.org/x/arch v0.0.0-20210405154355-08b684f594a5/go.mod h1:flIaEI6LNU6xOCD5PaJvn9wGP0agmIOqjrtsKGRguv4=
+golang.org/x/arch v0.0.0-20210923205945-b76863e36670/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
-golang.org/x/mod v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
-golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
+golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210119212857-b64e53b001e4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57 h1:F5Gozwx4I1xtr/sr/8CFbb57iKi3297KFs0QDbGN60A=
+golang.org/x/sys v0.0.0-20210809222454-d867a43fc93e/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20211030160813-b3129d9d1021 h1:giLT+HuUP/gXYrG2Plg9WTjj4qhfgaW424ZIFog3rlk=
+golang.org/x/sys v0.0.0-20211030160813-b3129d9d1021/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
-golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
-golang.org/x/tools v0.1.0 h1:po9/4sTYwZU9lPhi1tOrb4hCv3qrhiQ77LZfGa2OjwY=
+golang.org/x/tools v0.1.7 h1:6j8CgantCy3yc8JGBqkDLMKWqZ0RDU2g1HVgacojGWQ=
-golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
+golang.org/x/tools v0.1.7/go.mod h1:LGqMHiF4EqQNHR1JncWGqT5BVaXmza+X+BDGol+dOxo=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=

field/fe_alias_test.go

@@ -77,11 +77,11 @@ func checkAliasingTwoArgs(f func(v, x, y *Element) *Element) func(v, x, y Elemen
 // TestAliasing checks that receivers and arguments can alias each other without
 // leading to incorrect results. That is, it ensures that it's safe to write
 //
-//     v.Invert(v)
+//	v.Invert(v)
 //
 // or
 //
-//     v.Add(v, v)
+//	v.Add(v, v)
 //
 // without any of the inputs getting clobbered by the output being written.
 func TestAliasing(t *testing.T) {

field/fe_amd64.go

@@ -1,13 +1,16 @@
 // Code generated by command: go run fe_amd64_asm.go -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field. DO NOT EDIT.
 
+//go:build amd64 && gc && !purego
 // +build amd64,gc,!purego
 
 package field
 
 // feMul sets out = a * b. It works like feMulGeneric.
+//
 //go:noescape
 func feMul(out *Element, a *Element, b *Element)
 
 // feSquare sets out = a * a. It works like feSquareGeneric.
+//
 //go:noescape
 func feSquare(out *Element, a *Element)

field/fe_amd64.s

@@ -1,5 +1,6 @@
 // Code generated by command: go run fe_amd64_asm.go -out ../fe_amd64.s -stubs ../fe_amd64.go -pkg field. DO NOT EDIT.
 
+//go:build amd64 && gc && !purego
 // +build amd64,gc,!purego
 
 #include "textflag.h"

field/fe_extra.go

@@ -7,7 +7,7 @@ package field
 import "errors"
 
 // This file contains additional functionality that is not included in the
-// upstream crypto/ed25519/internal/edwards25519/field package.
+// upstream crypto/ed25519/edwards25519/field package.
 
 // SetWideBytes sets v to x, where x is a 64-byte little-endian encoding, which
 // is reduced modulo the field order. If x is not of the right length,

scalar.go

@@ -12,7 +12,7 @@ import (
 
 // A Scalar is an integer modulo
 //
-//     l = 2^252 + 27742317777372353535851937790883648493
+//	l = 2^252 + 27742317777372353535851937790883648493
 //
 // which is the prime order of the edwards25519 group.
 //
@@ -183,13 +183,15 @@ func load4(in []byte) int64 {
 }
 
 // Input:
-//   a[0]+256*a[1]+...+256^31*a[31] = a
+//
-//   b[0]+256*b[1]+...+256^31*b[31] = b
+//	a[0]+256*a[1]+...+256^31*a[31] = a
-//   c[0]+256*c[1]+...+256^31*c[31] = c
+//	b[0]+256*b[1]+...+256^31*b[31] = b
+//	c[0]+256*c[1]+...+256^31*c[31] = c
 //
 // Output:
-//   s[0]+256*s[1]+...+256^31*s[31] = (ab+c) mod l
+//
-//   where l = 2^252 + 27742317777372353535851937790883648493.
+//	s[0]+256*s[1]+...+256^31*s[31] = (ab+c) mod l
+//	where l = 2^252 + 27742317777372353535851937790883648493.
 func scMulAdd(s, a, b, c *[32]byte) {
 	a0 := 2097151 & load3(a[:])
 	a1 := 2097151 & (load4(a[2:]) >> 5)
@@ -616,11 +618,13 @@ func scMulAdd(s, a, b, c *[32]byte) {
 }
 
 // Input:
-//   s[0]+256*s[1]+...+256^63*s[63] = s
+//
+//	s[0]+256*s[1]+...+256^63*s[63] = s
 //
 // Output:
-//   s[0]+256*s[1]+...+256^31*s[31] = s mod l
+//
-//   where l = 2^252 + 27742317777372353535851937790883648493.
+//	s[0]+256*s[1]+...+256^31*s[31] = s mod l
+//	where l = 2^252 + 27742317777372353535851937790883648493.
 func scReduce(out *[32]byte, s *[64]byte) {
 	s0 := 2097151 & load3(s[:])
 	s1 := 2097151 & (load4(s[2:]) >> 5)

tables.go

@@ -40,7 +40,7 @@ func (v *projLookupTable) FromP3(q *Point) {
 	for i := 0; i < 7; i++ {
 		// Compute (i+1)*Q as Q + i*Q and convert to a ProjCached
 		// This is needlessly complicated because the API has explicit
-		// recievers instead of creating stack objects and relying on RVO
+		// receivers instead of creating stack objects and relying on RVO
 		v.points[i+1].FromP3(tmpP3.fromP1xP1(tmpP1xP1.Add(q, &v.points[i])))
 	}
 }