Golang golang-ppk-crypto (snippet)

Go programming example 'golang-ppk-crypto'

golang-ppk-crypto

Golang beginners example: golang-ppk-crypto

package main

import (
    "crypto/ecdsa"
    "crypto/elliptic"
    "crypto/rand"
    "crypto/x509"
    "fmt"
    "io"
    "math/big"
    "os"
)

func genPPKeys(random io.Reader) (private_key_bytes, public_key_bytes []byte) {
    private_key, _ := ecdsa.GenerateKey(elliptic.P224(), random)
    private_key_bytes, _ = x509.MarshalECPrivateKey(private_key)
    public_key_bytes, _ = x509.MarshalPKIXPublicKey(&private_key.PublicKey)
    return private_key_bytes, public_key_bytes
}

func pkSign(hash []byte, private_key_bytes []byte) (r, s *big.Int, err error) {
    zero := big.NewInt(0)
    private_key, err := x509.ParseECPrivateKey(private_key_bytes)
    if err != nil {
        return zero, zero, err
    }

    r, s, err = ecdsa.Sign(rand.Reader, private_key, hash)
    if err != nil {
        return zero, zero, err
    }
    return r, s, nil
}

func pkVerify(hash []byte, public_key_bytes []byte, r *big.Int, s *big.Int) (result bool) {
    public_key, err := x509.ParsePKIXPublicKey(public_key_bytes)
    if err != nil {
        return false
    }

    switch public_key := public_key.(type) {
    case *ecdsa.PublicKey:
        return ecdsa.Verify(public_key, hash, r, s)
    default:
        return false
    }
}

func main() {
    var str []byte
    if len(os.Args) > 1 {
        str = []byte(os.Args[1])
    } else {
        str = []byte("Lorem Ipsum dolor sit Amet")
    }

    private_key, public_key := genPPKeys(rand.Reader)
    fmt.Print("private key: ")
    fmt.Println(private_key)
    fmt.Println()
    fmt.Print("public key: ")
    fmt.Println(public_key)
    fmt.Println()

    r, s, err := pkSign(str, private_key)
    if err != nil {
        fmt.Printf("signing hash error: %s\n", err)
    }

    verify := pkVerify(str, public_key, r, s)
    fmt.Printf("signature verification result: %t\n", verify)

    verify = pkVerify([]byte("some other text"), public_key, r, s)
    fmt.Printf("signature verification result: %t\n", verify)
}

Useful links

• Learn Go: https://golangr.com
• Download Go: https://golang.org