des加密解密源代码(des加密算法源代码)
admin 发布:2022-12-19 19:31 112
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本文目录一览:
如何利用DES加密的算法保护Java源代码
Java语言是一种非常适用于网络编程的语言,它的基本结构与C++极为相似,但抛弃了C/C++中指针等内容,同时它吸收了Smalltalk、C++面向对象的编程思想。它具有简单性、鲁棒性、可移植性、动态性等特点。这些特点使得Java成为跨平台应用开发的一种规范,在世界范围内广泛流传。 加密Java源码的原因 Java源代码经过编译以后在JVM中执行。由于JVM界面是完全透明的,Java类文件能够很容易通过反编译器重新转换成源代码。因此,所有的算法、类文件等都可以以源代码的形式被公开,使得软件不能受到保护,为了保护产权,一般可以有以下几种方法: (1)"模糊"类文件,加大反编译器反编译源代码文件的难度。然而,可以修改反编译器,使之能够处理这些模糊类文件。所以仅仅依赖"模糊类文件"来保证代码的安全是不够的。 (2)流行的加密工具对源文件进行加密,比如PGP(Pretty Good Privacy)或GPG(GNU Privacy Guard)。这时,最终用户在运行应用之前必须先进行解密。但解密之后,最终用户就有了一份不加密的类文件,这和事先不进行加密没有什么差别。 (3)加密类文件,在运行中JVM用定制的类装载器(Class Loader)解密类文件。Java运行时装入字节码的机制隐含地意味着可以对字节码进行修改。JVM每次装入类文件时都需要一个称为ClassLoader的对象,这个对象负责把新的类装入正在运行的JVM。JVM给ClassLoader一个包含了待装入类(例如java.lang.Object)名字的字符串,然后由ClassLoader负责找到类文件,装入原始数据,并把它转换成一个Class对象。 用户下载的是加密过的类文件,在加密类文件装入之时进行解密,因此可以看成是一种即时解密器。由于解密后的字节码文件永远不会保存到文件系统,所以窃密者很难得到解密后的代码。 由于把原始字节码转换成Class对象的过程完全由系统负责,所以创建定制ClassLoader对象其实并不困难,只需先获得原始数据,接着就可以进行包含解密在内的任何转换。 Java密码体系和Java密码扩展 Java密码体系(JCA)和Java密码扩展(JCE)的设计目的是为Java提供与实现无关的加密函数API。它们都用factory方法来创建类的例程,然后把实际的加密函数委托给提供者指定的底层引擎,引擎中为类提供了服务提供者接口在Java中实现数据的加密/解密,是使用其内置的JCE(Java加密扩展)来实现的。Java开发工具集1.1为实现包括数字签名和信息摘要在内的加密功能,推出了一种基于供应商的新型灵活应用编程接口。Java密码体系结构支持供应商的互操作,同时支持硬件和软件实现。 Java密码学结构设计遵循两个原则: (1)算法的独立性和可靠性。 (2)实现的独立性和相互作用性。 算法的独立性是通过定义密码服务类来获得。用户只需了解密码算法的概念,而不用去关心如何实现这些概念。实现的独立性和相互作用性通过密码服务提供器来实现。密码服务提供器是实现一个或多个密码服务的一个或多个程序包。软件开发商根据一定接口,将各种算法实现后,打包成一个提供器,用户可以安装不同的提供器。安装和配置提供器,可将包含提供器的ZIP和JAR文件放在CLASSPATH下,再编辑Java安全属性文件来设置定义一个提供器。Java运行环境Sun版本时, 提供一个缺省的提供器Sun。 下面介绍DES算法及如何利用DES算法加密和解密类文件的步骤。 DES算法简介 DES(Data Encryption Standard)是发明最早的最广泛使用的分组对称加密算法。DES算法的入口参数有三个:Key、Data、Mode。
des算法源代码
des.h文件:
#ifndef CRYPTOPP_DES_H
#define CRYPTOPP_DES_H
#include "cryptlib.h"
#include "misc.h"
NAMESPACE_BEGIN(CryptoPP)
class DES : public BlockTransformation
{
public:
DES(const byte *userKey, CipherDir);
void ProcessBlock(const byte *inBlock, byte * outBlock) const;
void ProcessBlock(byte * inoutBlock) const
{DES::ProcessBlock(inoutBlock, inoutBlock);}
enum {KEYLENGTH=8, BLOCKSIZE=8};
unsigned int BlockSize() const {return BLOCKSIZE;}
protected:
static const word32 Spbox[8][64];
SecBlockword32 k;
};
class DESEncryption : public DES
{
public:
DESEncryption(const byte * userKey)
: DES (userKey, ENCRYPTION) {}
};
class DESDecryption : public DES
{
public:
DESDecryption(const byte * userKey)
: DES (userKey, DECRYPTION) {}
};
class DES_EDE_Encryption : public BlockTransformation
{
public:
DES_EDE_Encryption(const byte * userKey)
: e(userKey, ENCRYPTION), d(userKey + DES::KEYLENGTH, DECRYPTION) {}
void ProcessBlock(const byte *inBlock, byte * outBlock) const;
void ProcessBlock(byte * inoutBlock) const;
enum {KEYLENGTH=16, BLOCKSIZE=8};
unsigned int BlockSize() const {return BLOCKSIZE;}
private:
DES e, d;
};
class DES_EDE_Decryption : public BlockTransformation
{
public:
DES_EDE_Decryption(const byte * userKey)
: d(userKey, DECRYPTION), e(userKey + DES::KEYLENGTH, ENCRYPTION) {}
void ProcessBlock(const byte *inBlock, byte * outBlock) const;
void ProcessBlock(byte * inoutBlock) const;
enum {KEYLENGTH=16, BLOCKSIZE=8};
unsigned int BlockSize() const {return BLOCKSIZE;}
private:
DES d, e;
};
class TripleDES_Encryption : public BlockTransformation
{
public:
TripleDES_Encryption(const byte * userKey)
: e1(userKey, ENCRYPTION), d(userKey + DES::KEYLENGTH, DECRYPTION),
e2(userKey + 2*DES::KEYLENGTH, ENCRYPTION) {}
void ProcessBlock(const byte *inBlock, byte * outBlock) const;
void ProcessBlock(byte * inoutBlock) const;
enum {KEYLENGTH=24, BLOCKSIZE=8};
unsigned int BlockSize() const {return BLOCKSIZE;}
private:
DES e1, d, e2;
};
class TripleDES_Decryption : public BlockTransformation
{
public:
TripleDES_Decryption(const byte * userKey)
: d1(userKey + 2*DES::KEYLENGTH, DECRYPTION), e(userKey + DES::KEYLENGTH, ENCRYPTION),
d2(userKey, DECRYPTION) {}
void ProcessBlock(const byte *inBlock, byte * outBlock) const;
void ProcessBlock(byte * inoutBlock) const;
enum {KEYLENGTH=24, BLOCKSIZE=8};
unsigned int BlockSize() const {return BLOCKSIZE;}
private:
DES d1, e, d2;
};
NAMESPACE_END
#endif
des.cpp文件:
// des.cpp - modified by Wei Dai from:
/*
* This is a major rewrite of my old public domain DES code written
* circa 1987, which in turn borrowed heavily from Jim Gillogly's 1977
* public domain code. I pretty much kept my key scheduling code, but
* the actual encrypt/decrypt routines are taken from from Richard
* Outerbridge's DES code as printed in Schneier's "Applied Cryptography."
*
* This code is in the public domain. I would appreciate bug reports and
* enhancements.
*
* Phil Karn KA9Q, karn@unix.ka9q.ampr.org, August 1994.
*/
#include "pch.h"
#include "misc.h"
#include "des.h"
NAMESPACE_BEGIN(CryptoPP)
/* Tables defined in the Data Encryption Standard documents
* Three of these tables, the initial permutation, the final
* permutation and the expansion operator, are regular enough that
* for speed, we hard-code them. They're here for reference only.
* Also, the S and P boxes are used by a separate program, gensp.c,
* to build the combined SP box, Spbox[]. They're also here just
* for reference.
*/
#ifdef notdef
/* initial permutation IP */
static byte ip[] = {
58, 50, 42, 34, 26, 18, 10, 2,
60, 52, 44, 36, 28, 20, 12, 4,
62, 54, 46, 38, 30, 22, 14, 6,
64, 56, 48, 40, 32, 24, 16, 8,
57, 49, 41, 33, 25, 17, 9, 1,
59, 51, 43, 35, 27, 19, 11, 3,
61, 53, 45, 37, 29, 21, 13, 5,
63, 55, 47, 39, 31, 23, 15, 7
};
/* final permutation IP^-1 */
static byte fp[] = {
40, 8, 48, 16, 56, 24, 64, 32,
39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30,
37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28,
35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26,
33, 1, 41, 9, 49, 17, 57, 25
};
/* expansion operation matrix */
static byte ei[] = {
32, 1, 2, 3, 4, 5,
4, 5, 6, 7, 8, 9,
8, 9, 10, 11, 12, 13,
12, 13, 14, 15, 16, 17,
16, 17, 18, 19, 20, 21,
20, 21, 22, 23, 24, 25,
24, 25, 26, 27, 28, 29,
28, 29, 30, 31, 32, 1
};
/* The (in)famous S-boxes */
static byte sbox[8][64] = {
/* S1 */
14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13,
/* S2 */
15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9,
/* S3 */
10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12,
/* S4 */
7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14,
/* S5 */
2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3,
/* S6 */
12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13,
/* S7 */
4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12,
/* S8 */
13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11
};
/* 32-bit permutation function P used on the output of the S-boxes */
static byte p32i[] = {
16, 7, 20, 21,
29, 12, 28, 17,
1, 15, 23, 26,
5, 18, 31, 10,
2, 8, 24, 14,
32, 27, 3, 9,
19, 13, 30, 6,
22, 11, 4, 25
};
#endif
/* permuted choice table (key) */
static const byte pc1[] = {
57, 49, 41, 33, 25, 17, 9,
1, 58, 50, 42, 34, 26, 18,
10, 2, 59, 51, 43, 35, 27,
19, 11, 3, 60, 52, 44, 36,
63, 55, 47, 39, 31, 23, 15,
7, 62, 54, 46, 38, 30, 22,
14, 6, 61, 53, 45, 37, 29,
21, 13, 5, 28, 20, 12, 4
};
/* number left rotations of pc1 */
static const byte totrot[] = {
1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28
};
/* permuted choice key (table) */
static const byte pc2[] = {
14, 17, 11, 24, 1, 5,
3, 28, 15, 6, 21, 10,
23, 19, 12, 4, 26, 8,
16, 7, 27, 20, 13, 2,
41, 52, 31, 37, 47, 55,
30, 40, 51, 45, 33, 48,
44, 49, 39, 56, 34, 53,
46, 42, 50, 36, 29, 32
};
/* End of DES-defined tables */
/* bit 0 is left-most in byte */
static const int bytebit[] = {
0200,0100,040,020,010,04,02,01
};
/* Set key (initialize key schedule array) */
DES::DES(const byte *key, CipherDir dir)
: k(32)
{
SecByteBlock buffer(56+56+8);
byte *const pc1m=buffer; /* place to modify pc1 into */
byte *const pcr=pc1m+56; /* place to rotate pc1 into */
byte *const ks=pcr+56;
register int i,j,l;
int m;
for (j=0; j56; j++) { /* convert pc1 to bits of key */
l=pc1[j]-1; /* integer bit location */
m = l 07; /* find bit */
pc1m[j]=(key[l3] /* find which key byte l is in */
bytebit[m]) /* and which bit of that byte */
? 1 : 0; /* and store 1-bit result */
}
for (i=0; i16; i++) { /* key chunk for each iteration */
memset(ks,0,8); /* Clear key schedule */
for (j=0; j56; j++) /* rotate pc1 the right amount */
pcr[j] = pc1m[(l=j+totrot[i])(j28? 28 : 56) ? l: l-28];
/* rotate left and right halves independently */
for (j=0; j48; j++){ /* select bits individually */
/* check bit that goes to ks[j] */
if (pcr[pc2[j]-1]){
/* mask it in if it's there */
l= j % 6;
ks[j/6] |= bytebit[l] 2;
}
}
/* Now convert to odd/even interleaved form for use in F */
k[2*i] = ((word32)ks[0] 24)
| ((word32)ks[2] 16)
| ((word32)ks[4] 8)
| ((word32)ks[6]);
k[2*i+1] = ((word32)ks[1] 24)
| ((word32)ks[3] 16)
| ((word32)ks[5] 8)
| ((word32)ks[7]);
}
if (dir==DECRYPTION) // reverse key schedule order
for (i=0; i16; i+=2)
{
std::swap(k[i], k[32-2-i]);
std::swap(k[i+1], k[32-1-i]);
}
}
/* End of C code common to both versions */
/* C code only in portable version */
// Richard Outerbridge's initial permutation algorithm
/*
inline void IPERM(word32 left, word32 right)
{
word32 work;
work = ((left 4) ^ right) 0x0f0f0f0f;
right ^= work;
left ^= work 4;
work = ((left 16) ^ right) 0xffff;
right ^= work;
left ^= work 16;
work = ((right 2) ^ left) 0x33333333;
left ^= work;
right ^= (work 2);
work = ((right 8) ^ left) 0xff00ff;
left ^= work;
right ^= (work 8);
right = rotl(right, 1);
work = (left ^ right) 0xaaaaaaaa;
left ^= work;
right ^= work;
left = rotl(left, 1);
}
inline void FPERM(word32 left, word32 right)
{
word32 work;
right = rotr(right, 1);
work = (left ^ right) 0xaaaaaaaa;
left ^= work;
right ^= work;
left = rotr(left, 1);
work = ((left 8) ^ right) 0xff00ff;
right ^= work;
left ^= work 8;
work = ((left 2) ^ right) 0x33333333;
right ^= work;
left ^= work 2;
work = ((right 16) ^ left) 0xffff;
left ^= work;
right ^= work 16;
work = ((right 4) ^ left) 0x0f0f0f0f;
left ^= work;
right ^= work 4;
}
*/
// Wei Dai's modification to Richard Outerbridge's initial permutation
// algorithm, this one is faster if you have access to rotate instructions
// (like in MSVC)
inline void IPERM(word32 left, word32 right)
{
word32 work;
right = rotl(right, 4U);
work = (left ^ right) 0xf0f0f0f0;
left ^= work;
right = rotr(right^work, 20U);
work = (left ^ right) 0xffff0000;
left ^= work;
right = rotr(right^work, 18U);
work = (left ^ right) 0x33333333;
left ^= work;
right = rotr(right^work, 6U);
work = (left ^ right) 0x00ff00ff;
left ^= work;
right = rotl(right^work, 9U);
work = (left ^ right) 0xaaaaaaaa;
left = rotl(left^work, 1U);
right ^= work;
}
inline void FPERM(word32 left, word32 right)
{
word32 work;
right = rotr(right, 1U);
work = (left ^ right) 0xaaaaaaaa;
right ^= work;
left = rotr(left^work, 9U);
work = (left ^ right) 0x00ff00ff;
right ^= work;
left = rotl(left^work, 6U);
work = (left ^ right) 0x33333333;
right ^= work;
left = rotl(left^work, 18U);
work = (left ^ right) 0xffff0000;
right ^= work;
left = rotl(left^work, 20U);
work = (left ^ right) 0xf0f0f0f0;
right ^= work;
left = rotr(left^work, 4U);
}
// Encrypt or decrypt a block of data in ECB mode
void DES::ProcessBlock(const byte *inBlock, byte * outBlock) const
{
word32 l,r,work;
#ifdef IS_LITTLE_ENDIAN
l = byteReverse(*(word32 *)inBlock);
r = byteReverse(*(word32 *)(inBlock+4));
#else
l = *(word32 *)inBlock;
r = *(word32 *)(inBlock+4);
#endif
IPERM(l,r);
const word32 *kptr=k;
for (unsigned i=0; i8; i++)
{
work = rotr(r, 4U) ^ kptr[4*i+0];
l ^= Spbox[6][(work) 0x3f]
^ Spbox[4][(work 8) 0x3f]
^ Spbox[2][(work 16) 0x3f]
^ Spbox[0][(work 24) 0x3f];
work = r ^ kptr[4*i+1];
l ^= Spbox[7][(work) 0x3f]
^ Spbox[5][(work 8) 0x3f]
^ Spbox[3][(work 16) 0x3f]
^ Spbox[1][(work 24) 0x3f];
work = rotr(l, 4U) ^ kptr[4*i+2];
r ^= Spbox[6][(work) 0x3f]
^ Spbox[4][(work 8) 0x3f]
^ Spbox[2][(work 16) 0x3f]
^ Spbox[0][(work 24) 0x3f];
work = l ^ kptr[4*i+3];
r ^= Spbox[7][(work) 0x3f]
^ Spbox[5][(work 8) 0x3f]
^ Spbox[3][(work 16) 0x3f]
^ Spbox[1][(work 24) 0x3f];
}
FPERM(l,r);
#ifdef IS_LITTLE_ENDIAN
*(word32 *)outBlock = byteReverse(r);
*(word32 *)(outBlock+4) = byteReverse(l);
#else
*(word32 *)outBlock = r;
*(word32 *)(outBlock+4) = l;
#endif
}
void DES_EDE_Encryption::ProcessBlock(byte *inoutBlock) const
{
e.ProcessBlock(inoutBlock);
d.ProcessBlock(inoutBlock);
e.ProcessBlock(inoutBlock);
}
void DES_EDE_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
e.ProcessBlock(inBlock, outBlock);
d.ProcessBlock(outBlock);
e.ProcessBlock(outBlock);
}
void DES_EDE_Decryption::ProcessBlock(byte *inoutBlock) const
{
d.ProcessBlock(inoutBlock);
e.ProcessBlock(inoutBlock);
d.ProcessBlock(inoutBlock);
}
void DES_EDE_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
d.ProcessBlock(inBlock, outBlock);
e.ProcessBlock(outBlock);
d.ProcessBlock(outBlock);
}
void TripleDES_Encryption::ProcessBlock(byte *inoutBlock) const
{
e1.ProcessBlock(inoutBlock);
d.ProcessBlock(inoutBlock);
e2.ProcessBlock(inoutBlock);
}
void TripleDES_Encryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
e1.ProcessBlock(inBlock, outBlock);
d.ProcessBlock(outBlock);
e2.ProcessBlock(outBlock);
}
void TripleDES_Decryption::ProcessBlock(byte *inoutBlock) const
{
d1.ProcessBlock(inoutBlock);
e.ProcessBlock(inoutBlock);
d2.ProcessBlock(inoutBlock);
}
void TripleDES_Decryption::ProcessBlock(const byte *inBlock, byte *outBlock) const
{
d1.ProcessBlock(inBlock, outBlock);
e.ProcessBlock(outBlock);
d2.ProcessBlock(outBlock);
}
NAMESPACE_END
des加密算法
des加密算法如下:
一、DES加密算法简介
DES(Data Encryption Standard)是目前最为流行的加密算法之一。DES是对称的,也就是说它使用同一个密钥来加密和解密数据。
DES还是一种分组加密算法,该算法每次处理固定长度的数据段,称之为分组。DES分组的大小是64位,如果加密的数据长度不是64位的倍数,可以按照某种具体的规则来填充位。
从本质上来说,DES的安全性依赖于虚假表象,从密码学的术语来讲就是依赖于“混乱和扩散”的原则。混乱的目的是为隐藏任何明文同密文、或者密钥之间的关系,而扩散的目的是使明文中的有效位和密钥一起组成尽可能多的密文。两者结合到一起就使得安全性变得相对较高。
DES算法具体通过对明文进行一系列的排列和替换操作来将其加密。过程的关键就是从给定的初始密钥中得到16个子密钥的函数。要加密一组明文,每个子密钥按照顺序(1-16)以一系列的位操作施加于数据上,每个子密钥一次,一共重复16次。每一次迭代称之为一轮。要对密文进行解密可以采用同样的步骤,只是子密钥是按照逆向的顺序(16-1)对密文进行处理。
二、DES加密算法加密原理
DES是采用分组加密。使用64位的分组长度和56位的密钥长度,将64位的输入经过一系列变换得到64位的输出。DES算法利用多次组合替代算法和换位算法,通过混淆和扩散的相互作用,把明文编辑成密码强度很高的密文。解密则使用了相同的步骤和相同的密钥。
64位数据为一组进行加密;
初始置换根据一张8*8的置换表,将64位的明文打乱
与56位的密钥经16轮次迭代运算形成的初始密文
最后经过初始逆置换得到分组的最终密文
求C语言编写的DES加密解密源代码
从别的地方抄来的
#include "stdio.h"
#include "time.h"
#include "stdlib.h"
#define PLAIN_FILE_OPEN_ERROR -1
#define KEY_FILE_OPEN_ERROR -2
#define CIPHER_FILE_OPEN_ERROR -3
#define OK 1;
typedef char ElemType;
/* 初始置换表IP */
int IP_Table[64] = { 57,49,41,33,25,17,9,1,
59,51,43,35,27,19,11,3,
61,53,45,37,29,21,13,5,
63,55,47,39,31,23,15,7,
56,48,40,32,24,16,8,0,
58,50,42,34,26,18,10,2,
60,52,44,36,28,20,12,4,
62,54,46,38,30,22,14,6};
/* 逆初始置换表IP^-1 */
int IP_1_Table[64] = {39,7,47,15,55,23,63,31,
38,6,46,14,54,22,62,30,
37,5,45,13,53,21,61,29,
36,4,44,12,52,20,60,28,
35,3,43,11,51,19,59,27,
34,2,42,10,50,18,58,26,
33,1,41,9,49,17,57,25,
32,0,40,8,48,16,56,24};
/* 扩充置换表E */
int E_Table[48] = {31, 0, 1, 2, 3, 4,
3, 4, 5, 6, 7, 8,
7, 8,9,10,11,12,
11,12,13,14,15,16,
15,16,17,18,19,20,
19,20,21,22,23,24,
23,24,25,26,27,28,
27,28,29,30,31, 0};
/* 置换函数P */
int P_Table[32] = {15,6,19,20,28,11,27,16,
0,14,22,25,4,17,30,9,
1,7,23,13,31,26,2,8,
18,12,29,5,21,10,3,24};
/* S盒 */
int S[8][4][16] =/* S1 */
{{{14,4,13,1,2,15,11,8,3,10,6,12,5,9,0,7},
{0,15,7,4,14,2,13,1,10,6,12,11,9,5,3,8},
{4,1,14,8,13,6,2,11,15,12,9,7,3,10,5,0},
{15,12,8,2,4,9,1,7,5,11,3,14,10,0,6,13}},
/* S2 */
{{15,1,8,14,6,11,3,4,9,7,2,13,12,0,5,10},
{3,13,4,7,15,2,8,14,12,0,1,10,6,9,11,5},
{0,14,7,11,10,4,13,1,5,8,12,6,9,3,2,15},
{13,8,10,1,3,15,4,2,11,6,7,12,0,5,14,9}},
/* S3 */
{{10,0,9,14,6,3,15,5,1,13,12,7,11,4,2,8},
{13,7,0,9,3,4,6,10,2,8,5,14,12,11,15,1},
{13,6,4,9,8,15,3,0,11,1,2,12,5,10,14,7},
{1,10,13,0,6,9,8,7,4,15,14,3,11,5,2,12}},
/* S4 */
{{7,13,14,3,0,6,9,10,1,2,8,5,11,12,4,15},
{13,8,11,5,6,15,0,3,4,7,2,12,1,10,14,9},
{10,6,9,0,12,11,7,13,15,1,3,14,5,2,8,4},
{3,15,0,6,10,1,13,8,9,4,5,11,12,7,2,14}},
/* S5 */
{{2,12,4,1,7,10,11,6,8,5,3,15,13,0,14,9},
{14,11,2,12,4,7,13,1,5,0,15,10,3,9,8,6},
{4,2,1,11,10,13,7,8,15,9,12,5,6,3,0,14},
{11,8,12,7,1,14,2,13,6,15,0,9,10,4,5,3}},
/* S6 */
{{12,1,10,15,9,2,6,8,0,13,3,4,14,7,5,11},
{10,15,4,2,7,12,9,5,6,1,13,14,0,11,3,8},
{9,14,15,5,2,8,12,3,7,0,4,10,1,13,11,6},
{4,3,2,12,9,5,15,10,11,14,1,7,6,0,8,13}},
/* S7 */
{{4,11,2,14,15,0,8,13,3,12,9,7,5,10,6,1},
{13,0,11,7,4,9,1,10,14,3,5,12,2,15,8,6},
{1,4,11,13,12,3,7,14,10,15,6,8,0,5,9,2},
{6,11,13,8,1,4,10,7,9,5,0,15,14,2,3,12}},
/* S8 */
{{13,2,8,4,6,15,11,1,10,9,3,14,5,0,12,7},
{1,15,13,8,10,3,7,4,12,5,6,11,0,14,9,2},
{7,11,4,1,9,12,14,2,0,6,10,13,15,3,5,8},
{2,1,14,7,4,10,8,13,15,12,9,0,3,5,6,11}}};
/* 置换选择1 */
int PC_1[56] = {56,48,40,32,24,16,8,
0,57,49,41,33,25,17,
9,1,58,50,42,34,26,
18,10,2,59,51,43,35,
62,54,46,38,30,22,14,
6,61,53,45,37,29,21,
13,5,60,52,44,36,28,
20,12,4,27,19,11,3};
/* 置换选择2 */
int PC_2[48] = {13,16,10,23,0,4,2,27,
14,5,20,9,22,18,11,3,
25,7,15,6,26,19,12,1,
40,51,30,36,46,54,29,39,
50,44,32,46,43,48,38,55,
33,52,45,41,49,35,28,31};
/* 对左移次数的规定 */
int MOVE_TIMES[16] = {1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1};
int ByteToBit(ElemType ch,ElemType bit[8]);
int BitToByte(ElemType bit[8],ElemType *ch);
int Char8ToBit64(ElemType ch[8],ElemType bit[64]);
int Bit64ToChar8(ElemType bit[64],ElemType ch[8]);
int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]);
int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]);
int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]);
int DES_ROL(ElemType data[56], int time);
int DES_IP_Transform(ElemType data[64]);
int DES_IP_1_Transform(ElemType data[64]);
int DES_E_Transform(ElemType data[48]);
int DES_P_Transform(ElemType data[32]);
int DES_SBOX(ElemType data[48]);
int DES_XOR(ElemType R[48], ElemType L[48],int count);
int DES_Swap(ElemType left[32],ElemType right[32]);
int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]);
int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48], ElemType plainBlock[8]);
int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile);
int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile);
/* 字节转换成二进制 */
int ByteToBit(ElemType ch, ElemType bit[8]){
int cnt;
for(cnt = 0;cnt 8; cnt++){
*(bit+cnt) = (chcnt)1;
}
return 0;
}
/* 二进制转换成字节 */
int BitToByte(ElemType bit[8],ElemType *ch){
int cnt;
for(cnt = 0;cnt 8; cnt++){
*ch |= *(bit + cnt)cnt;
}
return 0;
}
/* 将长度为8的字符串转为二进制位串 */
int Char8ToBit64(ElemType ch[8],ElemType bit[64]){
int cnt;
for(cnt = 0; cnt 8; cnt++){
ByteToBit(*(ch+cnt),bit+(cnt3));
}
return 0;
}
/* 将二进制位串转为长度为8的字符串 */
int Bit64ToChar8(ElemType bit[64],ElemType ch[8]){
int cnt;
memset(ch,0,8);
for(cnt = 0; cnt 8; cnt++){
BitToByte(bit+(cnt3),ch+cnt);
}
return 0;
}
/* 生成子密钥 */
int DES_MakeSubKeys(ElemType key[64],ElemType subKeys[16][48]){
ElemType temp[56];
int cnt;
DES_PC1_Transform(key,temp);/* PC1置换 */
for(cnt = 0; cnt 16; cnt++){/* 16轮跌代,产生16个子密钥 */
DES_ROL(temp,MOVE_TIMES[cnt]);/* 循环左移 */
DES_PC2_Transform(temp,subKeys[cnt]);/* PC2置换,产生子密钥 */
}
return 0;
}
/* 密钥置换1 */
int DES_PC1_Transform(ElemType key[64], ElemType tempbts[56]){
int cnt;
for(cnt = 0; cnt 56; cnt++){
tempbts[cnt] = key[PC_1[cnt]];
}
return 0;
}
/* 密钥置换2 */
int DES_PC2_Transform(ElemType key[56], ElemType tempbts[48]){
int cnt;
for(cnt = 0; cnt 48; cnt++){
tempbts[cnt] = key[PC_2[cnt]];
}
return 0;
}
/* 循环左移 */
int DES_ROL(ElemType data[56], int time){
ElemType temp[56];
/* 保存将要循环移动到右边的位 */
memcpy(temp,data,time);
memcpy(temp+time,data+28,time);
/* 前28位移动 */
memcpy(data,data+time,28-time);
memcpy(data+28-time,temp,time);
/* 后28位移动 */
memcpy(data+28,data+28+time,28-time);
memcpy(data+56-time,temp+time,time);
return 0;
}
/* IP置换 */
int DES_IP_Transform(ElemType data[64]){
int cnt;
ElemType temp[64];
for(cnt = 0; cnt 64; cnt++){
temp[cnt] = data[IP_Table[cnt]];
}
memcpy(data,temp,64);
return 0;
}
/* IP逆置换 */
int DES_IP_1_Transform(ElemType data[64]){
int cnt;
ElemType temp[64];
for(cnt = 0; cnt 64; cnt++){
temp[cnt] = data[IP_1_Table[cnt]];
}
memcpy(data,temp,64);
return 0;
}
/* 扩展置换 */
int DES_E_Transform(ElemType data[48]){
int cnt;
ElemType temp[48];
for(cnt = 0; cnt 48; cnt++){
temp[cnt] = data[E_Table[cnt]];
}
memcpy(data,temp,48);
return 0;
}
/* P置换 */
int DES_P_Transform(ElemType data[32]){
int cnt;
ElemType temp[32];
for(cnt = 0; cnt 32; cnt++){
temp[cnt] = data[P_Table[cnt]];
}
memcpy(data,temp,32);
return 0;
}
/* 异或 */
int DES_XOR(ElemType R[48], ElemType L[48] ,int count){
int cnt;
for(cnt = 0; cnt count; cnt++){
R[cnt] ^= L[cnt];
}
return 0;
}
/* S盒置换 */
int DES_SBOX(ElemType data[48]){
int cnt;
int line,row,output;
int cur1,cur2;
for(cnt = 0; cnt 8; cnt++){
cur1 = cnt*6;
cur2 = cnt2;
/* 计算在S盒中的行与列 */
line = (data[cur1]1) + data[cur1+5];
row = (data[cur1+1]3) + (data[cur1+2]2)
+ (data[cur1+3]1) + data[cur1+4];
output = S[cnt][line][row];
/* 化为2进制 */
data[cur2] = (output0X08)3;
data[cur2+1] = (output0X04)2;
data[cur2+2] = (output0X02)1;
data[cur2+3] = output0x01;
}
return 0;
}
/* 交换 */
int DES_Swap(ElemType left[32], ElemType right[32]){
ElemType temp[32];
memcpy(temp,left,32);
memcpy(left,right,32);
memcpy(right,temp,32);
return 0;
}
/* 加密单个分组 */
int DES_EncryptBlock(ElemType plainBlock[8], ElemType subKeys[16][48], ElemType cipherBlock[8]){
ElemType plainBits[64];
ElemType copyRight[48];
int cnt;
Char8ToBit64(plainBlock,plainBits);
/* 初始置换(IP置换) */
DES_IP_Transform(plainBits);
/* 16轮迭代 */
for(cnt = 0; cnt 16; cnt++){
memcpy(copyRight,plainBits+32,32);
/* 将右半部分进行扩展置换,从32位扩展到48位 */
DES_E_Transform(copyRight);
/* 将右半部分与子密钥进行异或操作 */
DES_XOR(copyRight,subKeys[cnt],48);
/* 异或结果进入S盒,输出32位结果 */
DES_SBOX(copyRight);
/* P置换 */
DES_P_Transform(copyRight);
/* 将明文左半部分与右半部分进行异或 */
DES_XOR(plainBits,copyRight,32);
if(cnt != 15){
/* 最终完成左右部的交换 */
DES_Swap(plainBits,plainBits+32);
}
}
/* 逆初始置换(IP^1置换) */
DES_IP_1_Transform(plainBits);
Bit64ToChar8(plainBits,cipherBlock);
return 0;
}
/* 解密单个分组 */
int DES_DecryptBlock(ElemType cipherBlock[8], ElemType subKeys[16][48],ElemType plainBlock[8]){
ElemType cipherBits[64];
ElemType copyRight[48];
int cnt;
Char8ToBit64(cipherBlock,cipherBits);
/* 初始置换(IP置换) */
DES_IP_Transform(cipherBits);
/* 16轮迭代 */
for(cnt = 15; cnt = 0; cnt--){
memcpy(copyRight,cipherBits+32,32);
/* 将右半部分进行扩展置换,从32位扩展到48位 */
DES_E_Transform(copyRight);
/* 将右半部分与子密钥进行异或操作 */
DES_XOR(copyRight,subKeys[cnt],48);
/* 异或结果进入S盒,输出32位结果 */
DES_SBOX(copyRight);
/* P置换 */
DES_P_Transform(copyRight);
/* 将明文左半部分与右半部分进行异或 */
DES_XOR(cipherBits,copyRight,32);
if(cnt != 0){
/* 最终完成左右部的交换 */
DES_Swap(cipherBits,cipherBits+32);
}
}
/* 逆初始置换(IP^1置换) */
DES_IP_1_Transform(cipherBits);
Bit64ToChar8(cipherBits,plainBlock);
return 0;
}
/* 加密文件 */
int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile){
FILE *plain,*cipher;
int count;
ElemType plainBlock[8],cipherBlock[8],keyBlock[8];
ElemType bKey[64];
ElemType subKeys[16][48];
if((plain = fopen(plainFile,"rb")) == NULL){
return PLAIN_FILE_OPEN_ERROR;
}
if((cipher = fopen(cipherFile,"wb")) == NULL){
return CIPHER_FILE_OPEN_ERROR;
}
/* 设置密钥 */
memcpy(keyBlock,keyStr,8);
/* 将密钥转换为二进制流 */
Char8ToBit64(keyBlock,bKey);
/* 生成子密钥 */
DES_MakeSubKeys(bKey,subKeys);
while(!feof(plain)){
/* 每次读8个字节,并返回成功读取的字节数 */
if((count = fread(plainBlock,sizeof(char),8,plain)) == 8){
DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
fwrite(cipherBlock,sizeof(char),8,cipher);
}
}
if(count){
/* 填充 */
memset(plainBlock + count,'\0',7 - count);
/* 最后一个字符保存包括最后一个字符在内的所填充的字符数量 */
plainBlock[7] = 8 - count;
DES_EncryptBlock(plainBlock,subKeys,cipherBlock);
fwrite(cipherBlock,sizeof(char),8,cipher);
}
fclose(plain);
fclose(cipher);
return OK;
}
/* 解密文件 */
int DES_Decrypt(char *cipherFile, char *keyStr,char *plainFile){
FILE *plain, *cipher;
int count,times = 0;
long fileLen;
ElemType plainBlock[8],cipherBlock[8],keyBlock[8];
ElemType bKey[64];
ElemType subKeys[16][48];
if((cipher = fopen(cipherFile,"rb")) == NULL){
return CIPHER_FILE_OPEN_ERROR;
}
if((plain = fopen(plainFile,"wb")) == NULL){
return PLAIN_FILE_OPEN_ERROR;
}
/* 设置密钥 */
memcpy(keyBlock,keyStr,8);
/* 将密钥转换为二进制流 */
Char8ToBit64(keyBlock,bKey);
/* 生成子密钥 */
DES_MakeSubKeys(bKey,subKeys);
/* 取文件长度 */
fseek(cipher,0,SEEK_END); /* 将文件指针置尾 */
fileLen = ftell(cipher); /* 取文件指针当前位置 */
rewind(cipher); /* 将文件指针重指向文件头 */
while(1){
/* 密文的字节数一定是8的整数倍 */
fread(cipherBlock,sizeof(char),8,cipher);
DES_DecryptBlock(cipherBlock,subKeys,plainBlock);
times += 8;
if(times fileLen){
fwrite(plainBlock,sizeof(char),8,plain);
}
else{
break;
}
}
/* 判断末尾是否被填充 */
if(plainBlock[7] 8){
for(count = 8 - plainBlock[7]; count 7; count++){
if(plainBlock[count] != '\0'){
break;
}
}
}
if(count == 7){/* 有填充 */
fwrite(plainBlock,sizeof(char),8 - plainBlock[7],plain);
}
else{/* 无填充 */
fwrite(plainBlock,sizeof(char),8,plain);
}
fclose(plain);
fclose(cipher);
return OK;
}
int main()
{ DES_Encrypt("1.txt","key.txt","2.txt");
system("pause");
DES_Decrypt("2.txt","key.txt","3.txt");
getchar();
return 0;
}
des算法加密解密的实现
一.加密
DES算法处理的数据对象是一组64比特的明文串。设该明文串为m=m1m2…m64 (mi=0或1)。明文串经过64比特的密钥K来加密,最后生成长度为64比特的密文E。其加密过程图示如下:
DES算法加密过程
对DES算法加密过程图示的说明如下:待加密的64比特明文串m,经过IP置换后,得到的比特串的下标列表如下:
IP 58 50 42 34 26 18 10 2
60 52 44 36 28 20 12 4
62 54 46 38 30 22 14 6
64 56 48 40 32 24 16 8
57 49 41 33 25 17 9 1
59 51 43 35 27 19 11 3
61 53 45 37 29 21 13 5
63 55 47 39 31 23 15 7
该比特串被分为32位的L0和32位的R0两部分。R0子密钥K1(子密钥的生成将在后面讲)经过变换f(R0,K1)(f变换将在下面讲)输出32位的比特串f1,f1与L0做不进位的二进制加法运算。运算规则为:
f1与L0做不进位的二进制加法运算后的结果赋给R1,R0则原封不动的赋给L1。L1与R0又做与以上完全相同的运算,生成L2,R2…… 一共经过16次运算。最后生成R16和L16。其中R16为L15与f(R15,K16)做不进位二进制加法运算的结果,L16是R15的直接赋值。
R16与L16合并成64位的比特串。值得注意的是R16一定要排在L16前面。R16与L16合并后成的比特串,经过置换IP-1后所得比特串的下标列表如下:
IP-1 40 8 48 16 56 24 64 32
39 7 47 15 55 23 63 31
38 6 46 14 54 22 62 30
37 5 45 13 53 21 61 29
36 4 44 12 52 20 60 28
35 3 43 11 51 19 59 27
34 2 42 10 50 18 58 26
33 1 41 9 49 17 57 25
经过置换IP-1后生成的比特串就是密文e.。
下面再讲一下变换f(Ri-1,Ki)。
它的功能是将32比特的输入再转化为32比特的输出。其过程如图所示:
对f变换说明如下:输入Ri-1(32比特)经过变换E后,膨胀为48比特。膨胀后的比特串的下标列表如下:
E: 32 1 2 3 4 5
4 5 6 7 8 9
8 9 10 11 12 13
12 13 14 15 16 17
16 17 18 19 20 21
20 21 22 23 24 25
24 25 26 27 28 29
28 29 30 31 32 31
膨胀后的比特串分为8组,每组6比特。各组经过各自的S盒后,又变为4比特(具体过程见后),合并后又成为32比特。该32比特经过P变换后,其下标列表如下:
P: 16 7 20 21
29 12 28 17
1 15 23 26
5 18 31 10
2 8 24 14
32 27 3 9
19 13 30 6
22 11 4 25
经过P变换后输出的比特串才是32比特的f (Ri-1,Ki)。
下面再讲一下S盒的变换过程。任取一S盒。见图:
在其输入b1,b2,b3,b4,b5,b6中,计算出x=b1*2+b6, y=b5+b4*2+b3*4+b2*8,再从Si表中查出x 行,y 列的值Sxy。将Sxy化为二进制,即得Si盒的输出。(S表如图所示)
至此,DES算法加密原理讲完了。在VC++6.0下的程序源代码为:
for(i=1;i=64;i++)
m1[i]=m[ip[i-1]];//64位明文串输入,经过IP置换。
下面进行迭代。由于各次迭代的方法相同只是输入输出不同,因此只给出其中一次。以第八次为例://进行第八次迭代。首先进行S盒的运算,输入32位比特串。
for(i=1;i=48;i++)//经过E变换扩充,由32位变为48位
RE1[i]=R7[E[i-1]];
for(i=1;i=48;i++)//与K8按位作不进位加法运算
RE1[i]=RE1[i]+K8[i];
for(i=1;i=48;i++)
{
if(RE1[i]==2)
RE1[i]=0;
}
for(i=1;i7;i++)//48位分成8组
{
s11[i]=RE1[i];
s21[i]=RE1[i+6];
s31[i]=RE1[i+12];
s41[i]=RE1[i+18];
s51[i]=RE1[i+24];
s61[i]=RE1[i+30];
s71[i]=RE1[i+36];
s81[i]=RE1[i+42];
}//下面经过S盒,得到8个数。S1,s2,s3,s4,s5,s6,s7,s8分别为S表
s[1]=s1[s11[6]+s11[1]*2][s11[5]+s11[4]*2+s11[3]*4+s11[2]*8];
s[2]=s2[s21[6]+s21[1]*2][s21[5]+s21[4]*2+s21[3]*4+s21[2]*8];
s[3]=s3[s31[6]+s31[1]*2][s31[5]+s31[4]*2+s31[3]*4+s31[2]*8];
s[4]=s4[s41[6]+s41[1]*2][s41[5]+s41[4]*2+s41[3]*4+s41[2]*8];
s[5]=s5[s51[6]+s51[1]*2][s51[5]+s51[4]*2+s51[3]*4+s51[2]*8];
s[6]=s6[s61[6]+s61[1]*2][s61[5]+s61[4]*2+s61[3]*4+s61[2]*8];
s[7]=s7[s71[6]+s71[1]*2][s71[5]+s71[4]*2+s71[3]*4+s71[2]*8];
s[8]=s8[s81[6]+s81[1]*2][s81[5]+s81[4]*2+s81[3]*4+s81[2]*8];
for(i=0;i8;i++)//8个数变换输出二进制
{
for(j=1;j5;j++)
{
temp[j]=s[i+1]%2;
s[i+1]=s[i+1]/2;
}
for(j=1;j5;j++)
f[4*i+j]=temp[5-j];
}
for(i=1;i33;i++)//经过P变换
frk[i]=f[P[i-1]];//S盒运算完成
for(i=1;i33;i++)//左右交换
L8[i]=R7[i];
for(i=1;i33;i++)//R8为L7与f(R,K)进行不进位二进制加法运算结果
{
R8[i]=L7[i]+frk[i];
if(R8[i]==2)
R8[i]=0;
}
[ 原创文档 本文适合中级读者 已阅读21783次 ] 文档 代码 工具
DES算法及其在VC++6.0下的实现(下)
作者:航天医学工程研究所四室 朱彦军
在《DES算法及其在VC++6.0下的实现(上)》中主要介绍了DES算法的基本原理,下面让我们继续:
二.子密钥的生成
64比特的密钥生成16个48比特的子密钥。其生成过程见图:
子密钥生成过程具体解释如下:
64比特的密钥K,经过PC-1后,生成56比特的串。其下标如表所示:
PC-1 57 49 41 33 25 17 9
1 58 50 42 34 26 18
10 2 59 51 43 35 27
19 11 3 60 52 44 36
63 55 47 39 31 23 15
7 62 54 46 38 30 22
14 6 61 53 45 37 29
21 13 5 28 20 12 4
该比特串分为长度相等的比特串C0和D0。然后C0和D0分别循环左移1位,得到C1和D1。C1和D1合并起来生成C1D1。C1D1经过PC-2变换后即生成48比特的K1。K1的下标列表为:
PC-2 14 17 11 24 1 5
3 28 15 6 21 10
23 19 12 4 26 8
16 7 27 20 13 2
41 52 31 37 47 55
30 40 51 45 33 48
44 49 39 56 34 53
46 42 50 36 29 32
C1、D1分别循环左移LS2位,再合并,经过PC-2,生成子密钥K2……依次类推直至生成子密钥K16。
注意:Lsi (I =1,2,….16)的数值是不同的。具体见下表:
迭代顺序 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
左移位数 1 1 2 2 2 2 2 2 1 2 2 2 2 2 2 1
生成子密钥的VC程序源代码如下:
for(i=1;i57;i++)//输入64位K,经过PC-1变为56位 k0[i]=k[PC_1[i-1]];
56位的K0,均分为28位的C0,D0。C0,D0生成K1和C1,D1。以下几次迭代方法相同,仅以生成K8为例。 for(i=1;i27;i++)//循环左移两位
{
C8[i]=C7[i+2];
D8[i]=D7[i+2];
}
C8[27]=C7[1];
D8[27]=D7[1];
C8[28]=C7[2];
D8[28]=D7[2];
for(i=1;i=28;i++)
{
C[i]=C8[i];
C[i+28]=D8[i];
}
for(i=1;i=48;i++)
K8[i]=C[PC_2[i-1]];//生成子密钥k8
注意:生成的子密钥不同,所需循环左移的位数也不同。源程序中以生成子密钥 K8为例,所以循环左移了两位。但在编程中,生成不同的子密钥应以Lsi表为准。
三.解密
DES的解密过程和DES的加密过程完全类似,只不过将16圈的子密钥序列K1,K2……K16的顺序倒过来。即第一圈用第16个子密钥K16,第二圈用K15,其余类推。
第一圈:
加密后的结果
L=R15, R=L15⊕f(R15,K16)⊕f(R15,K16)=L15
同理R15=L14⊕f(R14,K15), L15=R14。
同理类推:
得 L=R0, R=L0。
其程序源代码与加密相同。在此就不重写。
四.示例
例如:已知明文m=learning, 密钥 k=computer。
明文m的ASCII二进制表示:
m= 01101100 01100101 01100001 01110010
01101110 01101001 01101110 01100111
密钥k的ASCII二进制表示:
k=01100011 01101111 01101101 01110000
01110101 01110100 01100101 01110010
明文m经过IP置换后,得:
11111111 00001000 11010011 10100110 00000000 11111111 01110001 11011000
等分为左右两段:
L0=11111111 00001000 11010011 10100110 R0=00000000 11111111 01110001 11011000
经过16次迭代后,所得结果为:
L1=00000000 11111111 01110001 11011000 R1=00110101 00110001 00111011 10100101
L2=00110101 00110001 00111011 10100101 R2=00010111 11100010 10111010 10000111
L3=00010111 11100010 10111010 10000111 R3=00111110 10110001 00001011 10000100
L4=00111110101100010000101110000100 R4=11110111110101111111101000111110
L5=11110111110101111111101000111110 R5=10010110011001110100111111100101
L6=10010110011001110100111111100101 R6=11001011001010000101110110100111
L7=11001011001010000101110110100111 R7=01100011110011101000111011011001
L8=01100011110011101000111011011001 R8=01001011110100001111001000000100
L9=01001011110100001111001000000100 R9=00011101001101111010111011100001
L10=00011101001101111010111011100001 R10=11101110111110111111010100000101
L11=11101110111110111111010100000101 R11=01101101111011011110010111111000
L12=01101101111011011110010111111000 R12=11111101110011100111000110110111
L13=11111101110011100111000110110111 R13=11100111111001011010101000000100
L14=11100111111001011010101000000100 R14=00011110010010011011100001100001
L15=00011110010010011011100001100001 R15=01010000111001001101110110100011
L16=01010000111001001101110110100011 R16=01111101101010000100110001100001
其中,f函数的结果为:
f1=11001010001110011110100000000011 f2=00010111000111011100101101011111
f3=00001011100000000011000000100001 f4=11100000001101010100000010111001
f5=10101000110101100100010001100001 f6=00111100111111111010011110011001
f7=11110101101010011100000100111100 f8=10000000111110001010111110100011
f9=01111110111110010010000000111000 f10=10100101001010110000011100000001
f11=01110000110110100100101100011001 f12=00010011001101011000010010110010
f13=10001010000010000100111111111100 f14=11100011100001111100100111010110
f15=10110111000000010111011110100111 f16=01100011111000011111010000000000
16个子密钥为:
K1=11110000101111101110111011010000 K2=11100000101111101111011010010101
K3=11110100111111100111011000101000 K4=11100110111101110111001000011010
K5=11101110110101110111011100100110 K6=11101111110100110101101110001011
K7=00101111110100111111101111100110 K8=10111111010110011101101101010000
K9=00011111010110111101101101000100 K10=00111111011110011101110100001001
K11=00011111011011011100110101101000 K12=01011011011011011011110100001010
K13=11011101101011011010110110001111 K14=11010011101011101010111110000000
K15=11111001101111101010011011010011 K16=11110001101111100010111000000001
S盒中,16次运算时,每次的8 个结果为:
第一次:5,11,4,1,0,3,13,9;
第二次:7,13,15,8,12,12,13,1;
第三次:8,0,0,4,8,1,9,12;
第四次:0,7,4,1,7,6,12,4;
第五次:8,1,0,11,5,0,14,14;
第六次:14,12,13,2,7,15,14,10;
第七次:12,15,15,1,9,14,0,4;
第八次:15,8,8,3,2,3,14,5;
第九次:8,14,5,2,1,15,5,12;
第十次:2,8,13,1,9,2,10,2;
第十一次:10,15,8,2,1,12,12,3;
第十二次:5,4,4,0,14,10,7,4;
第十三次:2,13,10,9,2,4,3,13;
第十四次:13,7,14,9,15,0,1,3;
第十五次:3,1,15,5,11,9,11,4;
第十六次:12,3,4,6,9,3,3,0;
子密钥生成过程中,生成的数值为:
C0=0000000011111111111111111011 D0=1000001101110110000001101000
C1=0000000111111111111111110110 D1=0000011011101100000011010001
C2=0000001111111111111111101100 D2=0000110111011000000110100010
C3=0000111111111111111110110000 D3=0011011101100000011010001000
C4=0011111111111111111011000000 D4=1101110110000001101000100000
C5=1111111111111111101100000000 D5=0111011000000110100010000011
C6=1111111111111110110000000011 D6=1101100000011010001000001101
C7=1111111111111011000000001111 D7=0110000001101000100000110111
C8=1111111111101100000000111111 D8=1000000110100010000011011101
C9=1111111111011000000001111111 D9=0000001101000100000110111011
C10=1111111101100000000111111111 D10=0000110100010000011011101100
C11=1111110110000000011111111111 D11=0011010001000001101110110000
C12=1111011000000001111111111111 D12=1101000100000110111011000000
C13=1101100000000111111111111111 D13=0100010000011011101100000011
C14=0110000000011111111111111111 D14=0001000001101110110000001101
C15=1000000001111111111111111101 D15=0100000110111011000000110100
C16=0000000011111111111111111011 D16=1000001101110110000001101000
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