• Jeffrey Wilcke's avatar
    consensus, core/*, params: metropolis preparation refactor · 10a57fc3
    Jeffrey Wilcke authored
    This commit is a preparation for the upcoming metropolis hardfork. It
    prepares the state, core and vm packages such that integration with
    metropolis becomes less of a hassle.
    
    * Difficulty calculation requires header instead of individual
      parameters
    * statedb.StartRecord renamed to statedb.Prepare and added Finalise
      method required by metropolis, which removes unwanted accounts from
      the state (i.e. selfdestruct)
    * State keeps record of destructed objects (in addition to dirty
      objects)
    * core/vm pre-compiles may now return errors
    * core/vm pre-compiles gas check now take the full byte slice as argument
      instead of just the size
    * core/vm now keeps several hard-fork instruction tables instead of a
      single instruction table and removes the need for hard-fork checks in
      the instructions
    * core/vm contains a empty restruction function which is added in
      preparation of metropolis write-only mode operations
    * Adds the bn256 curve
    * Adds and sets the metropolis chain config block parameters (2^64-1)
    10a57fc3
example_test.go 1.14 KB
// Copyright 2012 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 bn256

import (
	"crypto/rand"
)

func ExamplePair() {
	// This implements the tripartite Diffie-Hellman algorithm from "A One
	// Round Protocol for Tripartite Diffie-Hellman", A. Joux.
	// http://www.springerlink.com/content/cddc57yyva0hburb/fulltext.pdf

	// Each of three parties, a, b and c, generate a private value.
	a, _ := rand.Int(rand.Reader, Order)
	b, _ := rand.Int(rand.Reader, Order)
	c, _ := rand.Int(rand.Reader, Order)

	// Then each party calculates g₁ and g₂ times their private value.
	pa := new(G1).ScalarBaseMult(a)
	qa := new(G2).ScalarBaseMult(a)

	pb := new(G1).ScalarBaseMult(b)
	qb := new(G2).ScalarBaseMult(b)

	pc := new(G1).ScalarBaseMult(c)
	qc := new(G2).ScalarBaseMult(c)

	// Now each party exchanges its public values with the other two and
	// all parties can calculate the shared key.
	k1 := Pair(pb, qc)
	k1.ScalarMult(k1, a)

	k2 := Pair(pc, qa)
	k2.ScalarMult(k2, b)

	k3 := Pair(pa, qb)
	k3.ScalarMult(k3, c)

	// k1, k2 and k3 will all be equal.
}