gtsocial-umbx

curve25519.go (2156B)

---

 // 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.
 //
 // Starting in Go 1.20, this package is a wrapper for the X25519 implementation
 // in the crypto/ecdh package.
 package curve25519 // import "golang.org/x/crypto/curve25519"
 
 // 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) {
 	scalarMult(dst, scalar, point)
 }
 
 // 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) {
 	scalarBaseMult(dst, scalar)
 }
 
 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}
 
 func init() { Basepoint = basePoint[:] }
 
 // 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)
 }