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// Copyright © 2021 siddharth <s@ricketyspace.net>
// SPDX-License-Identifier: ISC
package lib
import "math/big"
type DH struct {
p *big.Int
g *big.Int
pk *big.Int // Private key
}
func NewDH(ps, gs string) (*DH, bool) {
p, ok := new(big.Int).SetString(StripSpaceChars(ps), 16)
if !ok {
return nil, false
}
g, ok := new(big.Int).SetString(StripSpaceChars(gs), 16)
if !ok {
return nil, false
}
// Init DH.
dh := new(DH)
dh.p = p
dh.g = g
dh.pk = big.NewInt(RandomInt(1, 10000000))
return dh, true
}
// Return our public key.
func (dh *DH) Pub() *big.Int {
return new(big.Int).Exp(dh.g, dh.pk, dh.p)
}
// Return shared secret between us and the other party.
// `pub` is the other party's public key.
func (dh *DH) SharedSecret(pub *big.Int) *big.Int {
return new(big.Int).Exp(pub, dh.pk, dh.p)
}
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