用c语言实现md5算法用c语言实现md5算法，这个够复杂。用c语言实现md5算法.
1)global.h 头文件
ifndef prototypes
define prototypes 0
endif
pointer defines a generic pointer type*/
typedef unsigned char*pointer;uint4 defines a four byte word*/
typedef unsigned long int uint4;proto_l**t ** defined depending on how prototypes ** defined
above.if using prototypes,then proto_l**t returns the l**t,otherw**e
it returns an empty l**t.*/
if prototypes
define proto_l**t(l**t)l**t
else
define proto_l**t(l**t)()
endif
2)md5.h 头文件
md5 context.*/
typedef struct {
uint4 state[4];state(abcd)*/
uint4 count[2];number of bits,modulo 2^64(l** first)*/
unsigned char buffer[64];input buffer*/
} md5_ctx;void md5init proto_l**t((md5_ctx*));void md5update proto_l**t
((md5_ctx*,unsigned char*,unsigned int));void md5final proto_l**t((unsigned char[16],md5_ctx*));3)md5c.c 算法的核心部分
参考 rsa data security,inc.,md5 **-digest algorithm 的c源程
序
include"global.h
include"md5.h
md5的主循环的轮主要操作为a=b+((a+f(b,c,d)+m+t)值如下:
define s11 7
define s12 12
define s13 17
define s14 22
define s21 5
define s22 9
define s23 14
define s24 20
define s31 4
define s32 11
define s33 16
define s34 23
define s41 6
define s42 10
define s43 15
define s44 21
函数调用说明*/
static void md5transform proto_l**t((uint4[4],unsigned char[64]));static void encode proto_l**t
((unsigned char*,uint4*,unsigned int));static void decode proto_l**t
((uint4*,unsigned char*,unsigned int));static void md5_memcpy proto_l**t((pointer,pointer,unsigned
int));static void md5_memset proto_l**t((pointer,int,unsigned int));static unsigned char padding[64]={
0x80,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
};f,g,h and i 是md5的基本函数.
define f(x,y,z)(((x)&(y))|((~x)&(z)))
define g(x,y,z)(((x)&(z))|((y)&(~z)))
define h(x,y,z)((x)^(y)^(z))
define i(x,y,z)((y)^((x)|(~z)))
rotate_left将 x 循环左移n bits.*/
define rotate_left(x,n)(((x)(32-(n))))
ff,gg,hh,and ii 代表1,2,3,4轮计算,先宏定义以便于后面引用.
define ff(a,b,c,d,x,s,ac){ \
(a)+f((b),(c),(d))+(x)+(uint4)(ac);\
(a)=rotate_left((a),(s));\
(a)+(b);\
}
define gg(a,b,c,d,x,s,ac){ \
(a)+g((b),(c),(d))+(x)+(uint4)(ac);\
(a)=rotate_left((a),(s));\
(a)+(b);\
}
define hh(a,b,c,d,x,s,ac){ \
(a)+h((b),(c),(d))+(x)+(uint4)(ac);\
(a)=rotate_left((a),(s));\
(a)+(b);\
}
define ii(a,b,c,d,x,s,ac){ \
(a)+i((b),(c),(d))+(x)+(uint4)(ac);\
(a)=rotate_left((a),(s));\
(a)+(b);\
}
md5 的初始化,md5 操作的开始.*/
void md5init(context)
md5_ctx*context;context*/
{
context->count[0]=context->count[1]=0;给出4个32比特的初始向量.*/
context->state[0]=0x67452301;context->state[1]=0xefcdab89;context->state[2]=0x98badcfe;context->state[3]=0x10325476;}
md5 块更新操作.不断地对消息块进行md5 消息-摘要操作,并更新
context.
void md5update(context,input,inputlen)
md5_ctx*context;context*/
unsigned char*input;input block*/
unsigned int inputlen;length of input block*/
{
unsigned int i,index,partlen;compute number of bytes mod 64*/
index=(unsigned int)((context->count[0]>>3)&0x3f);update number of bits*/
if((context->count[0]+((uint4)inputlen))
((uint4)inputlen context->count[1]+((uint4)inputlen>>29);partlen=64-index;transform as many times as possible.
if(inputlen>=partlen){
md5_memcpy
((pointer)&context->buffer[index],(pointer)input,partlen);md5transform(context->state,context->buffer);for(i=partlen;i+63 state,&input);index=0;}
else
i=0;buffer remaining input*/
md5_memcpy
((pointer)&context->buffer[index],(pointer)&input,
inputlen-i);}
md5 的结束操作.输出128比特的散列值并对context归零.
void md5final(digest,context)
unsigned char digest[16];** digest*/
md5_ctx*context;context*/
{
unsigned char bits[8];unsigned int index,padlen;s**e number of bits*/
encode(bits,context->count,8);pad out to 56 mod 64.
index=(unsigned int)((context->count[0]>>3)&0x3f);padlen=(index state,16);zeroize sensitive **rmation.
md5_memset((pointer)context,0,sizeof(*context));}
对一个消息块的16个子块进行md5 基本计算.
static void md5transform(state,block)
uint4 state[4];unsigned char block[64];{
uint4 a=state[0],b=state[1],c=state[2],d=state[3],x[16];decode(x,block,64);round 1*/
ff(a,b,c,d,x[0],s11,0xd76aa478);1*/
ff(d,a,b,c,x[1],s12,0xe8c7b756);2*/
ff(c,d,a,b,x[2],s13,0x242070db);3*/
ff(b,c,d,a,x[3],s14,0xc1bdceee);4*/
ff(a,b,c,d,x[4],s11,0xf57c0faf);5*/
ff(d,a,b,c,x[5],s12,0x4787c62a);6*/
ff(c,d,a,b,x[6],s13,0xa8304613);7*/
ff(b,c,d,a,x[7],s14,0xfd469501);8*/
ff(a,b,c,d,x[8],s11,0x698098d8);9*/
ff(d,a,b,c,x[9],s12,0x8b44f7af);10*/
ff(c,d,a,b,x[10],s13,0xffff5bb1);11*/
ff(b,c,d,a,x[11],s14,0x895cd7be);12*/
ff(a,b,c,d,x[12],s11,0x6b901122);13*/
ff(d,a,b,c,x[13],s12,0xfd987193);14*/
ff(c,d,a,b,x[14],s13,0xa679438e);15*/
ff(b,c,d,a,x[15],s14,0x49b40821);16*/
round 2*/
gg(a,b,c,d,x[1],s21,0xf61e2562);17*/
gg(d,a,b,c,x[6],s22,0xc040b340);18*/
gg(c,d,a,b,x[11],s23,0x265e5a51);19*/
gg(b,c,d,a,x[0],s24,0xe9b6c7aa);20*/
gg(a,b,c,d,x[5],s21,0xd62f105d);21*/
gg(d,a,b,c,x[10],s22,0x2441453);22*/
gg(c,d,a,b,x[15],s23,0xd8a1e681);23*/
gg(b,c,d,a,x[4],s24,0xe7d3fbc8);24*/
gg(a,b,c,d,x[9],s21,0x21e1cde6);25*/
gg(d,a,b,c,x[14],s22,0xc33707d6);26*/
gg(c,d,a,b,x[3],s23,0xf4d50d87);27*/
gg(b,c,...