Encrypt/Decrypt with KeyPair

main.go

package main

import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha256"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"log"
)

const (
	rawPrivateKey = `-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----`
	rawPublicKey = `-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDViO0h841VfHQJ8g1/AVBLbx3u
XCVl0kjMaBPjUUWhoGnOZSWrq9tdLe6ADC5SR01WiZwNKqnBDlkzgFaFNmOMAIaX
Frur5cCc1zyfEAOnG4LS/s13Tu/J/ibIAPcNkyh5q3gHU6AcUgves5srpsH4DZPv
mdrtd0xEFJ9P+ehdTwIDAQAB
-----END PUBLIC KEY-----`
)

func main() {

	content := []byte("something...")

	// private key
	block, _ := pem.Decode([]byte(rawPrivateKey))
	privateKey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
	if err != nil {
		log.Fatal(err)
	}

	// public key
	block, _ = pem.Decode([]byte(rawPublicKey))
	publicKey, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		log.Fatal(err)
	}

	// encrypt
	hash := sha256.New()
	encrypted, err := rsa.EncryptOAEP(hash, rand.Reader, publicKey.(*rsa.PublicKey), content, nil)
	if err != nil {
		log.Fatal(err)
	}

	// decrypt
	output, err := rsa.DecryptOAEP(hash, rand.Reader, privateKey, encrypted, nil)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("IsEqual?", bytes.Equal(content, output))
}

PKCS1v15.go

package main

import (
	"bytes"
	"crypto/rand"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"fmt"
	"log"
)

const (
	rawPrivateKey = `-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----`
	rawPublicKey = `-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDViO0h841VfHQJ8g1/AVBLbx3u
XCVl0kjMaBPjUUWhoGnOZSWrq9tdLe6ADC5SR01WiZwNKqnBDlkzgFaFNmOMAIaX
Frur5cCc1zyfEAOnG4LS/s13Tu/J/ibIAPcNkyh5q3gHU6AcUgves5srpsH4DZPv
mdrtd0xEFJ9P+ehdTwIDAQAB
-----END PUBLIC KEY-----`
)

func main() {

	content := []byte("something...")

	// private key
	block, _ := pem.Decode([]byte(rawPrivateKey))
	privateKey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
	if err != nil {
		log.Fatal(err)
	}

	// public key
	block, _ = pem.Decode([]byte(rawPublicKey))
	publicKey, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		log.Fatal(err)
	}

	// encrypt
	encrypted, err := rsa.EncryptPKCS1v15(rand.Reader, publicKey.(*rsa.PublicKey), content)
	if err != nil {
		log.Fatal(err)
	}

	// decrypt
	output, err := rsa.DecryptPKCS1v15(rand.Reader, privateKey, encrypted)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("IsEqual?", bytes.Equal(content, output))
}

https://levelup.gitconnected.com/a-guide-to-rsa-encryption-in-go-1a18d827f35d