Toy RSA implementation in Go

toyRsa.go

package main
import (
	"fmt"
	"math/big"
)
func encrypt(plainText string, e, n int) (cipherText []int) {
	for _, p := range plainText {
		//Exp sets c = p**e mod |n|
		c := new(big.Int).
			Exp(big.NewInt(int64(p)), big.NewInt(int64(e)), big.NewInt(int64(n))).
			Int64()
		cipherText = append(cipherText, int(c))
	}
	return
}

func decrypt(cipherText []int, d, n int) (plainText []byte) {
	for _, c := range cipherText {
		//Exp sets m = c**d mod |n|
		m := new(big.Int).
			Exp(big.NewInt(int64(c)), big.NewInt(int64(d)), big.NewInt(int64(n))).
			Int64()
		plainText = append(plainText, byte(m))
	}
	return
}
func main() {
	//https://simple.wikipedia.org/wiki/RSA_algorithm#A_working_example
	p := 61                      //1
	q := 53                      //1
	n := p * q                   //2 modulus
	totient := (q - 1) * (p - 1) //3 https://mathworld.wolfram.com/TotientFunction.html
	e := 17                      //4 exponent (coprime)
	d := int(new(big.Int).       //5 private exponent
		ModInverse(big.NewInt(int64(e)), big.NewInt(int64(totient))).
		Int64())
	plainText := "Please never implement your own encryption.\n"
	cipherText := encrypt(plainText, e, n)           // (e, n) is called a "public key"
	decodedText := string(decrypt(cipherText, d, n)) // (d) is called the "private key"
	fmt.Printf("Is identical: %t, text: %s", decodedText == plainText, decodedText)
}