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https://github.com/cheat/cheat.git
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47 lines
1.1 KiB
Go
47 lines
1.1 KiB
Go
// Copyright 2022 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build go1.20
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package curve25519
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import "crypto/ecdh"
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func x25519(dst *[32]byte, scalar, point []byte) ([]byte, error) {
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curve := ecdh.X25519()
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pub, err := curve.NewPublicKey(point)
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if err != nil {
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return nil, err
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}
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priv, err := curve.NewPrivateKey(scalar)
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if err != nil {
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return nil, err
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}
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out, err := priv.ECDH(pub)
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if err != nil {
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return nil, err
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}
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copy(dst[:], out)
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return dst[:], nil
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}
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func scalarMult(dst, scalar, point *[32]byte) {
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if _, err := x25519(dst, scalar[:], point[:]); err != nil {
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// The only error condition for x25519 when the inputs are 32 bytes long
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// is if the output would have been the all-zero value.
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for i := range dst {
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dst[i] = 0
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}
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}
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}
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func scalarBaseMult(dst, scalar *[32]byte) {
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curve := ecdh.X25519()
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priv, err := curve.NewPrivateKey(scalar[:])
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if err != nil {
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panic("curve25519: internal error: scalarBaseMult was not 32 bytes")
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}
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copy(dst[:], priv.PublicKey().Bytes())
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}
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