example_test.go

Documentation: golang.org/x/crypto/bn256

     1  // Copyright 2012 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package bn256
     6  
     7  import (
     8  	"crypto/rand"
     9  )
    10  
    11  func ExamplePair() {
    12  	// This implements the tripartite Diffie-Hellman algorithm from "A One
    13  	// Round Protocol for Tripartite Diffie-Hellman", A. Joux.
    14  	// http://www.springerlink.com/content/cddc57yyva0hburb/fulltext.pdf
    15  
    16  	// Each of three parties, a, b and c, generate a private value.
    17  	a, _ := rand.Int(rand.Reader, Order)
    18  	b, _ := rand.Int(rand.Reader, Order)
    19  	c, _ := rand.Int(rand.Reader, Order)
    20  
    21  	// Then each party calculates g₁ and g₂ times their private value.
    22  	pa := new(G1).ScalarBaseMult(a)
    23  	qa := new(G2).ScalarBaseMult(a)
    24  
    25  	pb := new(G1).ScalarBaseMult(b)
    26  	qb := new(G2).ScalarBaseMult(b)
    27  
    28  	pc := new(G1).ScalarBaseMult(c)
    29  	qc := new(G2).ScalarBaseMult(c)
    30  
    31  	// Now each party exchanges its public values with the other two and
    32  	// all parties can calculate the shared key.
    33  	k1 := Pair(pb, qc)
    34  	k1.ScalarMult(k1, a)
    35  
    36  	k2 := Pair(pc, qa)
    37  	k2.ScalarMult(k2, b)
    38  
    39  	k3 := Pair(pa, qb)
    40  	k3.ScalarMult(k3, c)
    41  
    42  	// k1, k2 and k3 will all be equal.
    43  }
    44
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