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authorLibravatar Tobi Smethurst <31960611+tsmethurst@users.noreply.github.com>2021-08-12 21:03:24 +0200
committerLibravatar GitHub <noreply@github.com>2021-08-12 21:03:24 +0200
commit98263a7de64269898a2f81207e38943b5c8e8653 (patch)
tree743c90f109a6c5d27832d1dcef2388d939f0f77a /vendor/golang.org/x/crypto/curve25519/curve25519.go
parentText duplication fix (#137) (diff)
downloadgotosocial-98263a7de64269898a2f81207e38943b5c8e8653.tar.xz
Grand test fixup (#138)
* start fixing up tests * fix up tests + automate with drone * fiddle with linting * messing about with drone.yml * some more fiddling * hmmm * add cache * add vendor directory * verbose * ci updates * update some little things * update sig
Diffstat (limited to 'vendor/golang.org/x/crypto/curve25519/curve25519.go')
-rw-r--r--vendor/golang.org/x/crypto/curve25519/curve25519.go145
1 files changed, 145 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/curve25519/curve25519.go b/vendor/golang.org/x/crypto/curve25519/curve25519.go
new file mode 100644
index 000000000..cda3fdd35
--- /dev/null
+++ b/vendor/golang.org/x/crypto/curve25519/curve25519.go
@@ -0,0 +1,145 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package curve25519 provides an implementation of the X25519 function, which
+// performs scalar multiplication on the elliptic curve known as Curve25519.
+// See RFC 7748.
+package curve25519 // import "golang.org/x/crypto/curve25519"
+
+import (
+ "crypto/subtle"
+ "fmt"
+
+ "golang.org/x/crypto/curve25519/internal/field"
+)
+
+// ScalarMult sets dst to the product scalar * point.
+//
+// Deprecated: when provided a low-order point, ScalarMult will set dst to all
+// zeroes, irrespective of the scalar. Instead, use the X25519 function, which
+// will return an error.
+func ScalarMult(dst, scalar, point *[32]byte) {
+ var e [32]byte
+
+ copy(e[:], scalar[:])
+ e[0] &= 248
+ e[31] &= 127
+ e[31] |= 64
+
+ var x1, x2, z2, x3, z3, tmp0, tmp1 field.Element
+ x1.SetBytes(point[:])
+ x2.One()
+ x3.Set(&x1)
+ z3.One()
+
+ swap := 0
+ for pos := 254; pos >= 0; pos-- {
+ b := e[pos/8] >> uint(pos&7)
+ b &= 1
+ swap ^= int(b)
+ x2.Swap(&x3, swap)
+ z2.Swap(&z3, swap)
+ swap = int(b)
+
+ tmp0.Subtract(&x3, &z3)
+ tmp1.Subtract(&x2, &z2)
+ x2.Add(&x2, &z2)
+ z2.Add(&x3, &z3)
+ z3.Multiply(&tmp0, &x2)
+ z2.Multiply(&z2, &tmp1)
+ tmp0.Square(&tmp1)
+ tmp1.Square(&x2)
+ x3.Add(&z3, &z2)
+ z2.Subtract(&z3, &z2)
+ x2.Multiply(&tmp1, &tmp0)
+ tmp1.Subtract(&tmp1, &tmp0)
+ z2.Square(&z2)
+
+ z3.Mult32(&tmp1, 121666)
+ x3.Square(&x3)
+ tmp0.Add(&tmp0, &z3)
+ z3.Multiply(&x1, &z2)
+ z2.Multiply(&tmp1, &tmp0)
+ }
+
+ x2.Swap(&x3, swap)
+ z2.Swap(&z3, swap)
+
+ z2.Invert(&z2)
+ x2.Multiply(&x2, &z2)
+ copy(dst[:], x2.Bytes())
+}
+
+// ScalarBaseMult sets dst to the product scalar * base where base is the
+// standard generator.
+//
+// It is recommended to use the X25519 function with Basepoint instead, as
+// copying into fixed size arrays can lead to unexpected bugs.
+func ScalarBaseMult(dst, scalar *[32]byte) {
+ ScalarMult(dst, scalar, &basePoint)
+}
+
+const (
+ // ScalarSize is the size of the scalar input to X25519.
+ ScalarSize = 32
+ // PointSize is the size of the point input to X25519.
+ PointSize = 32
+)
+
+// Basepoint is the canonical Curve25519 generator.
+var Basepoint []byte
+
+var basePoint = [32]byte{9, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
+
+func init() { Basepoint = basePoint[:] }
+
+func checkBasepoint() {
+ if subtle.ConstantTimeCompare(Basepoint, []byte{
+ 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+ }) != 1 {
+ panic("curve25519: global Basepoint value was modified")
+ }
+}
+
+// X25519 returns the result of the scalar multiplication (scalar * point),
+// according to RFC 7748, Section 5. scalar, point and the return value are
+// slices of 32 bytes.
+//
+// scalar can be generated at random, for example with crypto/rand. point should
+// be either Basepoint or the output of another X25519 call.
+//
+// If point is Basepoint (but not if it's a different slice with the same
+// contents) a precomputed implementation might be used for performance.
+func X25519(scalar, point []byte) ([]byte, error) {
+ // Outline the body of function, to let the allocation be inlined in the
+ // caller, and possibly avoid escaping to the heap.
+ var dst [32]byte
+ return x25519(&dst, scalar, point)
+}
+
+func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
+ var in [32]byte
+ if l := len(scalar); l != 32 {
+ return nil, fmt.Errorf("bad scalar length: %d, expected %d", l, 32)
+ }
+ if l := len(point); l != 32 {
+ return nil, fmt.Errorf("bad point length: %d, expected %d", l, 32)
+ }
+ copy(in[:], scalar)
+ if &point[0] == &Basepoint[0] {
+ checkBasepoint()
+ ScalarBaseMult(dst, &in)
+ } else {
+ var base, zero [32]byte
+ copy(base[:], point)
+ ScalarMult(dst, &in, &base)
+ if subtle.ConstantTimeCompare(dst[:], zero[:]) == 1 {
+ return nil, fmt.Errorf("bad input point: low order point")
+ }
+ }
+ return dst[:], nil
+}