status-go/vendor/github.com/decred/dcrd/dcrec/secp256k1/v4/ecdh.go

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// Copyright (c) 2015 The btcsuite developers
// Copyright (c) 2015-2023 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package secp256k1
// GenerateSharedSecret generates a shared secret based on a private key and a
// public key using Diffie-Hellman key exchange (ECDH) (RFC 5903).
// RFC5903 Section 9 states we should only return x.
//
// It is recommended to securely hash the result before using as a cryptographic
// key.
func GenerateSharedSecret(privkey *PrivateKey, pubkey *PublicKey) []byte {
var point, result JacobianPoint
pubkey.AsJacobian(&point)
ScalarMultNonConst(&privkey.Key, &point, &result)
result.ToAffine()
xBytes := result.X.Bytes()
return xBytes[:]
}