前往小程序,Get更优阅读体验!
立即前往
首页
学习
活动
专区
工具
TVP
发布
社区首页 >专栏 >加密解密 CTR IGE DH等

加密解密 CTR IGE DH等

作者头像
solate
发布2019-07-22 16:28:32
1.2K0
发布2019-07-22 16:28:32
举报
文章被收录于专栏:solate 杂货铺

加密解密

块加密

AES

IGE 模式

ige github例子

分组模式

CTR 模式

CTR 全称为计数器模式(Counter mode),该模式由 Diffe 和 Hellman 设计。一种分组密码的模式

DH 秘钥交换算法

一种密钥交换协议,注意该算法只能用于密钥的交换,而不能进行消息的加密和解密。双方确定要用的密钥后,要使用其他对称密钥操作加密算法实际加密和解密消息。它可以让双方在不泄漏密钥的情况下协商出一个密钥来, 常用于保证对称加密的秘钥的安全, TLS就是这样做的。

  • DH:ECDH是DH的加强版
  • ECDH: DH算法的加强版, 常用的是NIST系列,但是后面curve25519
  • curve25519: 实质上也是一种ECDH,但是其实现更为优秀,表现的更为安全,可能是下一代秘钥交换算法的标准。
DH go 的实现

引用git: dh go实现

代码语言:javascript
复制
// Use of this source code is governed by a license
// that can be found in the LICENSE file.

// Package dh implements the Diffie-Hellman key exchange over
// multiplicative groups of integers modulo a prime.
// This also defines some commen groups described in RFC 3526.
package dh

import (
	cryptorand "crypto/rand"
	"errors"
	"io"
	"math/big"
)

var zero *big.Int = big.NewInt(0)
var one *big.Int = big.NewInt(1)
var two *big.Int = big.NewInt(2)

// IsSafePrime returns true, if the prime of the group is
// a so called safe-prime. For a group with a safe-prime prime
// number the Decisional-Diffie-Hellman-Problem (DDH) is a
// 'hard' problem. The n argument is the number of iterations
// for the probabilistic prime test.
// It's recommend to use DDH-safe groups for DH-exchanges.
func IsSafePrimeGroup(g *Group, n int) bool {
	q := new(big.Int).Sub(g.P, one)
	q = q.Div(q, two)
	return q.ProbablyPrime(n)
}

// PublicKey is the type of DH public keys.
type PublicKey *big.Int

// PrivateKey is the type of DH private keys.
type PrivateKey *big.Int

// Group represents a mathematical group defined
// by a large prime and a generator.
type Group struct {
	P *big.Int // The prime
	G *big.Int // The generator
}

// GenerateKey generates a public/private key pair using entropy from rand.
// If rand is nil, crypto/rand.Reader will be used.
func (g *Group) GenerateKey(rand io.Reader) (private PrivateKey, public PublicKey, err error) {
	if g.P == nil {
		panic("crypto/dh: group prime is nil")
	}
	if g.G == nil {
		panic("crypto/dh: group generator is nil")
	}
	if rand == nil {
		rand = cryptorand.Reader
	}

	// Ensure, that p.G ^ privateKey > than g.P
	// (only modulo calculations are safe)
	// The minimal (and common) value for p.G is 2
	// So 2 ^ (1 + 'bitsize of p.G') > than g.P
	min := big.NewInt(int64(g.P.BitLen() + 1)) //生成一个不小于p的大数
	bytes := make([]byte, (g.P.BitLen()+7)/8)  //bit/8 = byte, +7 是为了补空,放置少除了,然后长度不够

	for private == nil {
		_, err = io.ReadFull(rand, bytes)
		if err != nil {
			private = nil
			return
		}
		// Clear bits in the first byte to increase
		// the probability that the candidate is < g.P.
		bytes[0] = 0
		if private == nil {
			private = new(big.Int)
		}
		(*private).SetBytes(bytes)   //将读到的数据设置进private中
		if (*private).Cmp(min) < 0 { //private 小于 一个不小于p的数。 如x < y返回-1;如x > y返回+1;否则返回0。
			private = nil
		}
	}

	public = new(big.Int).Exp(g.G, private, g.P) //x**y mod |m| =  A = g**a mod p
	return
}

// PublicKey returns the public key corresponding to the given private one.
func (g *Group) PublicKey(private PrivateKey) (public PublicKey) {
	public = new(big.Int).Exp(g.G, private, g.P)
	return
}

//private returns a non-nil error if the given public key is
// not a possible element of the group. This means, that the
// public key is < 0 or > g.P.
func (g *Group) Check(peersPublic PublicKey) (err error) {
	if !((*peersPublic).Cmp(zero) >= 0 && (*peersPublic).Cmp(g.P) == -1) {
		err = errors.New("peer's public is not a possible group element")
	}
	return
}

// ComputeSecret returns the secret computed from
// the own private and the peer's public key.
func (g *Group) ComputeSecret(private PrivateKey, peersPublic PublicKey) (secret *big.Int) {
	secret = new(big.Int).Exp(peersPublic, private, g.P)
	return
}

ECDH

全称是Elliptic Curve Diffie-Hellman, 是DH算法的加强版, 基于椭圆曲线难题加密, 现在是主流的密钥交换算法。

ECC是建立在基于椭圆曲线的离散对数的难度, 大概过程如下:

代码语言:javascript
复制
给定椭圆曲线上的一个点P,一个整数k,求解Q=kP很容易;给定一个点P、Q,知道Q=kP,求整数k确是一个难题。ECDH即建立在此数学难题之上
ECDH 和 curve25519 go的实现

引用: 密码学简介与Golang的加密库Crypto的使用

代码语言:javascript
复制
package main
import (
	"crypto"
	"crypto/elliptic"
	"crypto/rand"
	"fmt"
	"io"
	"math/big"
	"golang.org/x/crypto/curve25519"
)
// ECDH 秘钥交换算法的主接口
type ECDH interface {
	GenerateKey(io.Reader) (crypto.PrivateKey, crypto.PublicKey, error)
	Marshal(crypto.PublicKey) []byte
	Unmarshal([]byte) (crypto.PublicKey, bool)
	GenerateSharedSecret(crypto.PrivateKey, crypto.PublicKey) ([]byte, error)
}
type ellipticECDH struct {
	ECDH
	curve elliptic.Curve
}
type ellipticPublicKey struct {
	elliptic.Curve
	X, Y *big.Int
}
type ellipticPrivateKey struct {
	D []byte
}
// NewEllipticECDH 指定一种椭圆曲线算法用于创建一个ECDH的实例
// 关于椭圆曲线算法标准库里面实现了4种: 见crypto/elliptic
func NewEllipticECDH(curve elliptic.Curve) ECDH {
	return &ellipticECDH{
		curve: curve,
	}
}
// GenerateKey 基于标准库的NIST椭圆曲线算法生成秘钥对
func (e *ellipticECDH) GenerateKey(rand io.Reader) (crypto.PrivateKey, crypto.PublicKey, error) {
	var d []byte
	var x, y *big.Int
	var priv *ellipticPrivateKey
	var pub *ellipticPublicKey
	var err error
	d, x, y, err = elliptic.GenerateKey(e.curve, rand)
	if err != nil {
		return nil, nil, err
	}
	priv = &ellipticPrivateKey{
		D: d,
	}
	pub = &ellipticPublicKey{
		Curve: e.curve,
		X:     x,
		Y:     y,
	}
	return priv, pub, nil
}
// Marshal用于公钥的序列化
func (e *ellipticECDH) Marshal(p crypto.PublicKey) []byte {
	pub := p.(*ellipticPublicKey)
	return elliptic.Marshal(e.curve, pub.X, pub.Y)
}
// Unmarshal用于公钥的反序列化
func (e *ellipticECDH) Unmarshal(data []byte) (crypto.PublicKey, bool) {
	var key *ellipticPublicKey
	var x, y *big.Int
	x, y = elliptic.Unmarshal(e.curve, data)
	if x == nil || y == nil {
		return key, false
	}
	key = &ellipticPublicKey{
		Curve: e.curve,
		X:     x,
		Y:     y,
	}
	return key, true
}
// GenerateSharedSecret 通过自己的私钥和对方的公钥协商一个共享密码
func (e *ellipticECDH) GenerateSharedSecret(privKey crypto.PrivateKey, pubKey crypto.PublicKey) ([]byte, error) {
	priv := privKey.(*ellipticPrivateKey)
	pub := pubKey.(*ellipticPublicKey)
	x, _ := e.curve.ScalarMult(pub.X, pub.Y, priv.D)
	return x.Bytes(), nil
}
// NewCurve25519ECDH 使用密码学家Daniel J. Bernstein的椭圆曲线算法:Curve25519来创建ECDH实例
// 因为Curve25519独立于NIST之外, 没在标准库实现, 需要单独为期实现一套接口来支持ECDH
func NewCurve25519ECDH() ECDH {
	return &curve25519ECDH{}
}
type curve25519ECDH struct {
	ECDH
}
// GenerateKey 基于curve25519椭圆曲线算法生成秘钥对
func (e *curve25519ECDH) GenerateKey(rand io.Reader) (crypto.PrivateKey, crypto.PublicKey, error) {
	var pub, priv [32]byte
	var err error
	_, err = io.ReadFull(rand, priv[:])
	if err != nil {
		return nil, nil, err
	}
	priv[0] &= 248
	priv[31] &= 127
	priv[31] |= 64
	curve25519.ScalarBaseMult(&pub, &priv)
	return &priv, &pub, nil
}
// 实现公钥的序列化
func (e *curve25519ECDH) Marshal(p crypto.PublicKey) []byte {
	pub := p.(*[32]byte)
	return pub[:]
}
// 实现公钥的反序列化
func (e *curve25519ECDH) Unmarshal(data []byte) (crypto.PublicKey, bool) {
	var pub [32]byte
	if len(data) != 32 {
		return nil, false
	}
	copy(pub[:], data)
	return &pub, true
}
// 实现秘钥协商接口
func (e *curve25519ECDH) GenerateSharedSecret(privKey crypto.PrivateKey, pubKey crypto.PublicKey) ([]byte, error) {
	var priv, pub, secret *[32]byte
	priv = privKey.(*[32]byte)
	pub = pubKey.(*[32]byte)
	secret = new([32]byte)
	curve25519.ScalarMult(secret, priv, pub)
	return secret[:], nil
}
func test(e ECDH) {
	var privKey1, privKey2 crypto.PrivateKey
	var pubKey1, pubKey2 crypto.PublicKey
	var pubKey1Buf, pubKey2Buf []byte
	var err error
	var ok bool
	var secret1, secret2 []byte
	// 准备2对秘钥对,A: privKey1,pubKey1 B:privKey2,pubKey2
	privKey1, pubKey1, err = e.GenerateKey(rand.Reader)
	if err != nil {
		fmt.Println(err)
	}
	privKey2, pubKey2, err = e.GenerateKey(rand.Reader)
	if err != nil {
		fmt.Println(err)
	}
	pubKey1Buf = e.Marshal(pubKey1)
	pubKey2Buf = e.Marshal(pubKey2)
	pubKey1, ok = e.Unmarshal(pubKey1Buf)
	if !ok {
		fmt.Println("Unmarshal does not work")
	}
	pubKey2, ok = e.Unmarshal(pubKey2Buf)
	if !ok {
		fmt.Println("Unmarshal does not work")
	}
	// A 通过B给的公钥协商共享密码
	secret1, err = e.GenerateSharedSecret(privKey1, pubKey2)
	if err != nil {
		fmt.Println(err)
	}
	// B 通过A给的公钥协商共享密码
	secret2, err = e.GenerateSharedSecret(privKey2, pubKey1)
	if err != nil {
		fmt.Println(err)
	}
	// A B在没暴露直接的私钥的情况下, 协商出了一个共享密码
	fmt.Printf("The secret1 shared keys: %x\n", secret1)
	fmt.Printf("The secret2 shared keys: %x\n", secret2)
}
func main() {
	e1 := NewEllipticECDH(elliptic.P521())
	e2 := NewCurve25519ECDH()
	test(e1)
	test(e2)
本文参与 腾讯云自媒体同步曝光计划,分享自作者个人站点/博客。
如有侵权请联系 cloudcommunity@tencent.com 删除

本文分享自 作者个人站点/博客 前往查看

如有侵权,请联系 cloudcommunity@tencent.com 删除。

本文参与 腾讯云自媒体同步曝光计划  ,欢迎热爱写作的你一起参与!

评论
登录后参与评论
0 条评论
热度
最新
推荐阅读
目录
  • 加密解密
    • 块加密
      • AES
      • 分组模式
      • DH 秘钥交换算法
      • ECDH
相关产品与服务
专用宿主机
专用宿主机(CVM Dedicated Host,CDH)提供用户独享的物理服务器资源,满足您资源独享、资源物理隔离、安全、合规需求。专用宿主机搭载了腾讯云虚拟化系统,购买之后,您可在其上灵活创建、管理多个自定义规格的云服务器实例,自主规划物理资源的使用。
领券
问题归档专栏文章快讯文章归档关键词归档开发者手册归档开发者手册 Section 归档