package main
import (
	"crypto/rand"
	"crypto/rsa"
	"crypto/sha1"
	"crypto/x509"
	"encoding/pem"
	"fmt"
)
// 使用对方的公钥的数据, 只有对方的私钥才能解开
func encrypt(plain string, publicKey string) (cipherByte []byte, err error) {
	msg := []byte(plain)
	// 解码公钥
	pubBlock, _ := pem.Decode([]byte(publicKey))
	// 读取公钥
	pubKeyValue, err := x509.ParsePKIXPublicKey(pubBlock.Bytes)
	if err != nil {
		panic(err)
	}
	pub := pubKeyValue.(*rsa.PublicKey)
	// 加密数据方法: 不用使用EncryptPKCS1v15方法加密,源码里面推荐使用EncryptOAEP, 因此这里使用安全的方法加密
	encryptOAEP, err := rsa.EncryptOAEP(sha1.New(), rand.Reader, pub, msg, nil)
	if err != nil {
		panic(err)
	}
	cipherByte = encryptOAEP
	return
}
// 使用私钥解密公钥加密的数据
func decrypt(cipherByte []byte, privateKey string) (plainText string, err error) {
	// 解析出私钥
	priBlock, _ := pem.Decode([]byte(privateKey))
	priKey, err := x509.ParsePKCS1PrivateKey(priBlock.Bytes)
	if err != nil {
		panic(err)
	}
	// 解密RSA-OAEP方式加密后的内容
	decryptOAEP, err := rsa.DecryptOAEP(sha1.New(), rand.Reader, priKey, cipherByte, nil)
	if err != nil {
		panic(err)
	}
	plainText = string(decryptOAEP)
	return
}
func test() {
	msg := "Content bo be encrypted!"
	// 获取公钥, 生产环境往往是文件中读取, 这里为了测试方便, 直接生成了.
	publicKeyData := `-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDZsfv1qscqYdy4vY+P4e3cAtmv
ppXQcRvrF1cB4drkv0haU24Y7m5qYtT52Kr539RdbKKdLAM6s20lWy7+5C0Dgacd
wYWd/7PeCELyEipZJL07Vro7Ate8Bfjya+wltGK9+XNUIHiumUKULW4KDx21+1NL
AUeJ6PeW+DAkmJWF6QIDAQAB
-----END PUBLIC KEY-----
`
	// 获取私钥
	privateKeyData := `-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
`
	cipherData, err := encrypt(msg, publicKeyData)
	if err != nil {
		panic(err)
	}
	fmt.Printf("encrypt message: %x\n", cipherData)
	plainData, err := decrypt(cipherData, privateKeyData)
	if err != nil {
		panic(err)
	}
	fmt.Printf("decrypt message:%s\n", plainData)
}
func main() {
	test()
}

package main
import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/md5"
	"crypto/rand"
	"fmt"
	"hash"
	"io"
	"math/big"
)
// SignData 用于保存签名的数据
type SignData struct {
	r         *big.Int
	s         *big.Int
	signhash  *[]byte
	signature *[]byte
}
// 使用私钥签名一段数据
func sign(message string, privateKey *ecdsa.PrivateKey) (signData *SignData, err error) {
	// 签名数据
	var h hash.Hash
	h = md5.New()
	r := big.NewInt(0)
	s := big.NewInt(0)
	io.WriteString(h, message)
	signhash := h.Sum(nil)
	r, s, serr := ecdsa.Sign(rand.Reader, privateKey, signhash)
	if serr != nil {
		return nil, serr
	}
	signature := r.Bytes()
	signature = append(signature, s.Bytes()...)
	signData = &SignData{
		r:         r,
		s:         s,
		signhash:  &signhash,
		signature: &signature,
	}
	return
}
// 校验数字签名
func verifySign(signData *SignData, publicKey *ecdsa.PublicKey) (status bool) {
	status = ecdsa.Verify(publicKey, *signData.signhash, signData.r, signData.s)
	return
}
func test() {
	//使用椭圆曲线的P256算法,现在一共也就实现了4种,我们使用折中一种,具体见http://golang.org/pkg/crypto/elliptic/#P256
	pubkeyCurve := elliptic.P256()
	privateKey := new(ecdsa.PrivateKey)
	// 生成秘钥对
	privateKey, err := ecdsa.GenerateKey(pubkeyCurve, rand.Reader)
	if err != nil {
		panic(err)
	}
	var publicKey ecdsa.PublicKey
	publicKey = privateKey.PublicKey
	// 签名
	signData, err := sign("This is a message to be signed and verified by ECDSA!", privateKey)
	if err != nil {
		panic(err)
	}
	fmt.Printf("The signhash: %x\nThe signature: %x\n", *signData.signhash, *signData.signature)
	// 验证
	status := verifySign(signData, &publicKey)
	fmt.Printf("The verify result is: %v\n", status)
}
func main() {
	test()
}