www.pudn.com > sslref30.zip > qud_cksm.c

/* qud_cksm.c */ 
/* Copyright (C) 1993 Eric Young - see README for more details */ 
/* From "Message Authentication"  R.R. Jueneman, S.M. Matyas, C.H. Meyer 
 * IEEE Communications Magazine Sept 1985 Vol. 23 No. 9 p 29-40 
 * This module in only based on the code in this paper and is 
 * almost definitely not the same as the MIT implementation. 
 */ 
#include "des_locl.h" 
 
/* bug fix for dos - 7/6/91 - Larry hughes@logos.ucs.indiana.edu */ 
#define B0(a)   (((unsigned long)(a))) 
#define B1(a)   (((unsigned long)(a))<<8) 
#define B2(a)   (((unsigned long)(a))<<16) 
#define B3(a)   (((unsigned long)(a))<<24) 
 
/* used to scramble things a bit */ 
/* Got the value MIT uses via brute force :-) 2/10/90 eay */ 
#define NOISE   ((unsigned long)83653421) 
 
unsigned long des_quad_cksum(input,output,length,out_count,seed) 
des_cblock *input; 
des_cblock *output; 
long length; 
int out_count; 
des_cblock *seed; 
    { 
    unsigned long z0,z1,t0,t1; 
    int i; 
    long l=0; 
    unsigned char *cp; 
    unsigned char *lp; 
 
    if (out_count < 1) out_count=1; 
    lp=(unsigned char *)output; 
 
    z0=B0((*seed)[0])|B1((*seed)[1])|B2((*seed)[2])|B3((*seed)[3]); 
    z1=B0((*seed)[4])|B1((*seed)[5])|B2((*seed)[6])|B3((*seed)[7]); 
 
    for (i=0; ((i<4)&&(i 0) 
            { 
            if (l > 1) 
                { 
                t0= (unsigned long)(*(cp++)); 
                t0|=(unsigned long)B1(*(cp++)); 
                l--; 
                } 
            else 
                t0= (unsigned long)(*(cp++)); 
            l--; 
            /* add */ 
            t0+=z0; 
            t0&=0xffffffff; 
            t1=z1; 
            /* square, well sort of square */ 
            z0=((((t0*t0)&0xffffffff)+((t1*t1)&0xffffffff)) 
                &0xffffffff)%0x7fffffff;  
            z1=((t0*((t1+NOISE)&0xffffffff))&0xffffffff)%0x7fffffff; 
            } 
        if (lp != NULL) 
            { 
            /* I believe I finally have things worked out. 
             * The MIT library assumes that the checksum 
             * is one huge number and it is returned in a 
             * host dependant byte order. 
             */ 
            static unsigned long l=1; 
            static unsigned char *c=(unsigned char *)&l; 
 
            if (c[0]) 
                { 
                l2c(z0,lp); 
                l2c(z1,lp); 
                } 
            else 
                { 
                lp=output[out_count-i-1]; 
                l2n(z1,lp); 
                l2n(z0,lp); 
                } 
            } 
        } 
    return(z0); 
    }