go语言RSA API使用示例
第零步： 常用的包
import (
"os"
"fmt"
"log"
"errors"
"io/ioutil"
"crypto/rsa"
"crypto/rand"
"crypto/x509"
"crypto/sha256"
"encoding/pem"
"encoding/base64"
)
第一步：生成RSA密钥对, 包括private和public key
// Generate RSA private/public key
func GenerateKey() (*rsa.PrivateKey, *rsa.PublicKey, error) {
privatekey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, nil, err
}
publickey := &privatekey.PublicKey
return privatekey, publickey, nil
}
第二步：Dump key到文件
这样生成的key文件就是我们平常使用命令行工具openssl时用的key文件，比如key.pem，pub.key
// Dump private key into file
// This has same output as DumpPrivateKeyBuffer(), but dump to a file:
// -----BEGIN RSA PRIVATE KEY-----
// MIIEoQIBAAKCAQEAuql1lFYgKmKA1x5lQyadktbkeRRO0qrsmAkhvTtiz2p0Y+Ur
// xWSYqDlmoY6vdkxj0Ex0z4zisoPnI+K89hV69O9v/83Yz7hYkLBHuwGiiSOiPZU7
// ...
// PfKnburLQLE50wPkglfnGYfqQxtIiqn1hGTQO1xBxu03g+KM/Q==
// -----END RSA PRIVATE KEY-----
func DumpPrivateKeyFile(privatekey *rsa.PrivateKey, filename string) error {
var keybytes []byte = x509.MarshalPKCS1PrivateKey(privatekey)
block := &pem.Block{
Type : "RSA PRIVATE KEY",
Bytes : keybytes,
}
file, err := os.Create(filename)
if err != nil {
return err
}
err = pem.Encode(file, block)
if err != nil {
return err
}
return nil
}
// Dump public key into file
// -----BEGIN PUBLIC KEY-----
// MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2y8mEdCRE8siiI7udpge
// 5y1hrlSJzV7Xj0UojL/hi9u7s6TjYQQDA4M++/FezwkO5lBby2C+wK8bY7lgphuP
// ...
// OZPrh/jItinhdzhyIXuYn6ohesPlM9i5TMpeBfpBmCwQQTfsAjBnXTTQzT4m4cmo
// 2QIDAQAB
// -----END PUBLIC KEY-----
func DumpPublicKeyFile(publickey *rsa.PublicKey, filename string) error {
keybytes, err := x509.MarshalPKIXPublicKey(publickey)
if err != nil {
return err
}
block := &pem.Block{
Type : "PUBLIC KEY",
Bytes : keybytes,
}
file, err := os.Create(filename)
if err != nil {
return err
}
err = pem.Encode(file, block)
if err != nil {
return err
}
return nil
}
第三步：Dump key到缓存
Dump到缓存和Dump到文件的内容时一样的，只是是否输出到文件，还是输出到内存而已。
// Dump private key to buffer.
func DumpPrivateKeyBuffer(privatekey *rsa.PrivateKey) (string, error) {
var keybytes []byte = x509.MarshalPKCS1PrivateKey(privatekey)
block := &pem.Block{
Type : "RSA PRIVATE KEY",
Bytes : keybytes,
}
var keybuffer []byte = pem.EncodeToMemory(block)
return string(keybuffer), nil
}
func DumpPublicKeyBuffer(publickey *rsa.PublicKey) (string, error) {
keybytes, err := x509.MarshalPKIXPublicKey(publickey)
if err != nil {
return "", err
}
block := &pem.Block{
Type : "PUBLIC KEY",
Bytes : keybytes,
}
var keybuffer []byte = pem.EncodeToMemory(block)
return string(keybuffer), nil
}
第四步：Dump到字符串
以Base64的编码方式输出key，这个key是一个用户可见的单行字符串，方便key在API之间相互传递。
// Dump private key to base64 string
// Compared with DumpPrivateKeyBuffer this output:
// 1. Have no header/tailer line
// 2. Key content is merged into one-line format
// The output is:
// MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2y8mEdCRE8siiI7udpge......2QIDAQAB
func DumpPrivateKeyBase64(privatekey *rsa.PrivateKey) (string, error) {
var keybytes []byte = x509.MarshalPKCS1PrivateKey(privatekey)
keybase64 := base64.StdEncoding.EncodeToString(keybytes)
return keybase64, nil
}
func DumpPublicKeyBase64(publickey *rsa.PublicKey) (string, error) {
keybytes, err := x509.MarshalPKIXPublicKey(publickey)
if err != nil {
return "", err
}
keybase64 := base64.StdEncoding.EncodeToString(keybytes)
return keybase64, nil
}
第五步，从文件加载key
// Load private key from private key file
func LoadPrivateKeyFile(keyfile string) (*rsa.PrivateKey, error) {
keybuffer, err := ioutil.ReadFile(keyfile)
if err != nil {
return nil, err
}
block, _ := pem.Decode([]byte(keybuffer))
if block == nil {
return nil, errors.New("private key error!")
}
privatekey, err := x509.ParsePKCS1PrivateKey(block.Bytes)
if err != nil {
return nil, errors.New("parse private key error!")
}
return privatekey, nil
}
func LoadPublicKeyFile(keyfile string) (*rsa.PublicKey, error) {
keybuffer, err := ioutil.ReadFile(keyfile)
if err != nil {
return nil, err
}
block, _ := pem.Decode(keybuffer)
if block == nil {
return nil, errors.New("public key error")
}
pubkeyinterface, err := x509.ParsePKIXPublicKey(block.Bytes)
if err != nil {
return nil, err
}
publickey := pubkeyinterface.(*rsa.PublicKey)
return publickey, nil
}
第六步：从Base64字符串加载key
// Load private key from base64
func LoadPrivateKeyBase64(base64key string) (*rsa.PrivateKey, error) {
keybytes, err := base64.StdEncoding.DecodeString(base64key)
if err != nil {
return nil, fmt.Errorf("base64 decode failed, error=%s\n", err.Error())
}
privatekey, err := x509.ParsePKCS1PrivateKey(keybytes)
if err != nil {
return nil, errors.New("parse private key error!")
}
return privatekey, nil
}
func LoadPublicKeyBase64(base64key string) (*rsa.PublicKey, error) {
keybytes, err := base64.StdEncoding.DecodeString(base64key)
if err != nil {
return nil, fmt.Errorf("base64 decode failed, error=%s\n", err.Error())
}
pubkeyinterface, err := x509.ParsePKIXPublicKey(keybytes)
if err != nil {
return nil, err
}
publickey := pubkeyinterface.(*rsa.PublicKey)
return publickey, nil
}
第七步：加密字符串
并把解密后的字符串按照Base64编码。
// encrypt
func Encrypt(plaintext string, publickey *rsa.PublicKey) (string, error) {
label := []byte("")
sha256hash := sha256.New()
ciphertext, err := rsa.EncryptOAEP(sha256hash, rand.Reader, publickey, []byte(plaintext), label)
decodedtext := base64.StdEncoding.EncodeToString(ciphertext)
return decodedtext, err
}
第八步：解密字符串
解密已经经过Base64编码的密文，输出解密后的字符串。
// decrypt
func Decrypt(ciphertext string, privatekey *rsa.PrivateKey) (string, error) {
decodedtext, err := base64.StdEncoding.DecodeString(ciphertext)
if err != nil {
return "", fmt.Errorf("base64 decode failed, error=%s\n", err.Error())
}
sha256hash := sha256.New()
decryptedtext, err := rsa.DecryptOAEP(sha256hash, rand.Reader, privatekey, decodedtext, nil)
if err != nil {
return "", fmt.Errorf("RSA decrypt failed, error=%s\n", err.Error())
}
return string(decryptedtext), nil
}
第十步：把它们串起来测试
把前面定义的API串起来成一个可执行程序。
func main() {
// generate key
privatekey, publickey, err := GenerateKey()
if err != nil {
log.Fatalf("Cannot generate RSA key\n")
}
// dump private key to file
err = DumpPrivateKeyFile(privatekey, "private.pem")
if err != nil {
log.Fatalf("Cannot dump private key file\n")
}
// dump public key to file
err = DumpPublicKeyFile(publickey, "public.pem")
if err != nil {
log.Fatalf("Cannot dump public key file\n")
}
// encrypt message use public key
message := "abcd"
cipher, err := Encrypt(message, publickey)
if err != nil {
log.Fatalf("Cannot encrypt message\n")
}
// load private key
privatekey, err = LoadPrivateKeyFile("private.pem")
if privatekey == nil {
fmt.Printf("Cannot load private key\n");
}
// decrypt use private
plain, err := Decrypt(cipher, privatekey)
if err != nil {
log.Fatalf("Cannot decrypt message\n")
}
fmt.Printf("decrypt result is (%s)\n", plain)
}
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