i_skey.c File Reference

#include "idea.h"
#include "idea_lcl.h"

Go to the source code of this file.

Functions
static IDEA_INT	inverse (unsigned int xin)
void	idea_set_encrypt_key (const unsigned char *key, IDEA_KEY_SCHEDULE *ks)
void	idea_set_decrypt_key (IDEA_KEY_SCHEDULE *ek, IDEA_KEY_SCHEDULE *dk)

---

Function Documentation

void idea_set_decrypt_key	(	IDEA_KEY_SCHEDULE *	ek,
		IDEA_KEY_SCHEDULE *	dk
	)

Definition at line 97 of file i_skey.c.

References idea_key_st::data, IDEA_INT, and inverse().

        {
        int r;
        register IDEA_INT *fp,*tp,t;

        tp= &(dk->data[0][0]);
        fp= &(ek->data[8][0]);
        for (r=0; r<9; r++)
                {
                *(tp++)=inverse(fp[0]);
                *(tp++)=((int)(0x10000L-fp[2])&0xffff);
                *(tp++)=((int)(0x10000L-fp[1])&0xffff);
                *(tp++)=inverse(fp[3]);
                if (r == 8) break;
                fp-=6;
                *(tp++)=fp[4];
                *(tp++)=fp[5];
                }

        tp= &(dk->data[0][0]);
        t=tp[1];
        tp[1]=tp[2];
        tp[2]=t;

        t=tp[49];
        tp[49]=tp[50];
        tp[50]=t;
        }

void idea_set_encrypt_key	(	const unsigned char *	key,
		IDEA_KEY_SCHEDULE *	ks
	)

Definition at line 63 of file i_skey.c.

References idea_key_st::data, i, IDEA_INT, and n2s.

        {
        int i;
        register IDEA_INT *kt,*kf,r0,r1,r2;

        kt= &(ks->data[0][0]);
        n2s(key,kt[0]); n2s(key,kt[1]); n2s(key,kt[2]); n2s(key,kt[3]);
        n2s(key,kt[4]); n2s(key,kt[5]); n2s(key,kt[6]); n2s(key,kt[7]);

        kf=kt;
        kt+=8;
        for (i=0; i<6; i++)
                {
                r2= kf[1];
                r1= kf[2];
                *(kt++)= ((r2<<9) | (r1>>7))&0xffff;
                r0= kf[3];
                *(kt++)= ((r1<<9) | (r0>>7))&0xffff;
                r1= kf[4];
                *(kt++)= ((r0<<9) | (r1>>7))&0xffff;
                r0= kf[5];
                *(kt++)= ((r1<<9) | (r0>>7))&0xffff;
                r1= kf[6];
                *(kt++)= ((r0<<9) | (r1>>7))&0xffff;
                r0= kf[7];
                *(kt++)= ((r1<<9) | (r0>>7))&0xffff;
                r1= kf[0];
                if (i >= 5) break;
                *(kt++)= ((r0<<9) | (r1>>7))&0xffff;
                *(kt++)= ((r1<<9) | (r2>>7))&0xffff;
                kf+=8;
                }
        }

static IDEA_INT inverse

(

unsigned int

xin

)

[static]

Definition at line 127 of file i_skey.c.

References IDEA_INT.

Referenced by idea_set_decrypt_key().

        {
        long n1,n2,q,r,b1,b2,t;

        if (xin == 0)
                b2=0;
        else
                {
                n1=0x10001;
                n2=xin;
                b2=1;
                b1=0;

                do      {
                        r=(n1%n2);
                        q=(n1-r)/n2;
                        if (r == 0)
                                { if (b2 < 0) b2=0x10001+b2; }
                        else
                                {
                                n1=n2;
                                n2=r;
                                t=b2;
                                b2=b1-q*b2;
                                b1=t;
                                }
                        } while (r != 0);
                }
        return((IDEA_INT)b2);
        }