RSA

encrypt-decrypt.go

package main

import (
	"crypto/rand"
	"crypto/rsa"
	"log"
)

func main() {
	rnd := rand.Reader

	msg := []byte("Hello World")

	key, err := rsa.GenerateKey(rnd, 2048)
	if err != nil {
		log.Panicln(err)
	}

	enc, err := rsa.EncryptPKCS1v15(rnd, &key.PublicKey, msg)
	if err != nil {
		log.Panicln(err)
	}

	dec, err := rsa.DecryptPKCS1v15(rnd, key, enc)
	if err != nil {
		log.Panicln(err)
	}

	log.Println(string(dec) == string(msg))
}

sign-verify.go

package main

import (
	"crypto"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha256"
	"log"
)

func main() {
	rnd := rand.Reader

	msg := []byte("Hello World")

	key, err := rsa.GenerateKey(rnd, 2048)
	if err != nil {
		log.Panicln(err)
	}

	hashed := sha256.Sum256(msg)

	sig, err := rsa.SignPKCS1v15(rnd, key, crypto.SHA256, hashed[:])
	if err != nil {
		log.Panicln(err)
	}

	err = rsa.VerifyPKCS1v15(&key.PublicKey, crypto.SHA256, hashed[:], sig)
	if err != nil {
		log.Panicln(err)
	}
}