ecdh25519

Documentation

Overview

ECDH implementation with curve25519. https://tools.ietf.org/html/rfc7748

Index

• Variables
• type Pair
  • func New() (*Pair, error)
  • func Use(private []byte) (*Pair, error)
• type PrivateKey
  • func (pri PrivateKey) Bytes() []byte
  • func (pri PrivateKey) PlainSecret(pub PublicKey) ([]byte, error)
  • func (pri PrivateKey) Public() (PublicKey, error)
  • func (pri PrivateKey) Secret(pub PublicKey) (SharedSecret, error)
• type PublicKey
  • func (pub PublicKey) Bytes() []byte
• type SharedSecret
  • func (s SharedSecret) Bytes() []byte

Examples

• New
• PrivateKey.Secret
• Use

Variables

var (
	Basepoint []byte = curve25519.Basepoint
)

Types

type Pair

type Pair struct {
	Private PrivateKey
	Public  PublicKey
}

Pair holds private and public key.

func New

func New() (*Pair, error)

New generates a pair of a random private and corresponding public key. Private key consists of randomly generated bytes. (rfc7748 pages 7/8) Both keys size is 32 bytes.

Example

package main

import (
	"fmt"
	"log"

	"catinello.eu/ecdh25519"
)

func main() {
	p, err := ecdh25519.New()
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(len(p.Private), len(p.Public))
}

Output:
32 32

func Use

func Use(private []byte) (*Pair, error)

Use takes a []byte value of a valid PrivateKey and calculates a Pair.

Example

package main

import (
	"fmt"
	"log"

	"catinello.eu/ecdh25519"
)

var P1, P2 *ecdh25519.Pair

func main() {
	var err error

	P1, err = ecdh25519.Use([]byte{99, 75, 54, 81, 49, 102, 50, 108, 74, 97, 55, 88, 99, 75, 104, 88, 73, 56, 52, 88, 82, 55, 48, 116, 85, 79, 110, 122, 86, 99, 80, 107})
	if err != nil {
		log.Fatal(err)
	}

	P2, err = ecdh25519.Use([]byte{65, 76, 68, 75, 109, 112, 86, 72, 97, 73, 97, 105, 80, 81, 117, 49, 98, 70, 86, 88, 79, 82, 73, 98, 51, 66, 68, 69, 122, 66, 86, 77})
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(P1.Public, P2.Public)
}

Output:
[248 69 226 11 251 195 84 145 220 51 63 112 231 156 98 5 249 8 166 80 85 46 193 196 160 126 66 55 174 118 128 32] [16 141 48 51 183 25 22 123 3 152 245 146 201 38 250 197 76 66 151 193 249 54 234 131 21 125 51 140 131 131 183 111]

type PrivateKey

type PrivateKey []byte

func (PrivateKey) Bytes

func (pri PrivateKey) Bytes() []byte

func (PrivateKey) PlainSecret

func (pri PrivateKey) PlainSecret(pub PublicKey) ([]byte, error)

PlainSecret provides a shared secret (32 bytes) of the given private and public keys.

func (PrivateKey) Public

func (pri PrivateKey) Public() (PublicKey, error)

Public provides the PublicKey of the given PrivateKey.

func (PrivateKey) Secret

func (pri PrivateKey) Secret(pub PublicKey) (SharedSecret, error)

Secret provides a SHA3 hashed shared secret of the given private and public keys. SharedSecret size is 64 bytes hashed by SHAKE256.

Example

package main

import (
	"bytes"
	"fmt"
	"log"

	"catinello.eu/ecdh25519"
)

var P1, P2 *ecdh25519.Pair

func main() {
	s1, err := P1.Private.Secret(P2.Public)
	if err != nil {
		log.Fatal(err)
	}

	s2, err := P2.Private.Secret(P1.Public)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println(bytes.Compare(s1.Bytes(), s2.Bytes()))
}

Output:
0

type PublicKey

type PublicKey []byte

func (PublicKey) Bytes

func (pub PublicKey) Bytes() []byte

type SharedSecret

type SharedSecret []byte

func (SharedSecret) Bytes

func (s SharedSecret) Bytes() []byte