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MAIN/PROT/CRYPT.C

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+#include <io.h>
+#include <fcntl.h>
+#include <dos.h>
+#include <stdio.h>
+#include <string.h>
+
+extern int far arand();
+extern char far randtau[1024];
+char	far buf[64000];
+
+main()  {
+	int	p1, p2, p3, p4;
+	long	l,sl,w;
+	int	a,b,r;
+	int	f1;
+
+	if(_argc!=2) return(1);
+
+	f1=open(_argv[1],O_RDWR|O_BINARY);
+	if(f1==-1) return(1);
+	l=read(f1,buf,64000);
+	lseek(f1,0,SEEK_SET);
+
+	p1=0;
+	do do do while(buf[p1++]!=0x12); while(buf[p1++]!=0x34); while(buf[p1++]!=0x56); while(buf[p1++]!=0x78);
+	p2=p1;			// p2=cstart
+
+	do do do while(buf[p1++]!=0x12); while(buf[p1++]!=0x34); while(buf[p1++]!=0x56); while(buf[p1++]!=0x78);
+	for(a=p1-4;a<p2+768;a++) buf[a]=rand();
+	p3=p1-4;		// p3=randtau
+
+	p1=p2+768;
+	do do do while(buf[p1++]!=0x12); while(buf[p1++]!=0x34); while(buf[p1++]!=0x56); while(buf[p1++]!=0x78);
+	p4=p1-4;	   	// randtau code end
+	for(a=p4;a<p3+1024;a++) buf[a]=rand();
+
+	do do do while(buf[p1++]!=0x12); while(buf[p1++]!=0x34); while(buf[p1++]!=0x56); while(buf[p1++]!=0x78);
+	sl=p1-4;		// p1=crypt_start
+
+	asm  {
+		mov	ax, p1
+		add	ax, 29787d
+		mov	cx, 15553d
+		mul	cx
+		and	ax, 511d
+		mov	a, ax
+		}
+
+	for(;p1<l;p1++,a=(a+15553U)&511)
+		buf[a+p2+256]=buf[p1]^0x77;
+
+	memcpy(&randtau[0],&buf[p3],1024);
+	for(a=0;a<p2-4;a++) buf[a]=buf[a]^arand();
+
+//---------------------------------------------------------------------------
+	for(a=0,r=0;a<256*3;a++)
+		{
+		if(a<256) { r+=0x7a33; r*=0x2345; }
+		else if(a<256*2) { r+=0x455c; r*=0x825d; }
+		else { r+=0xaa4b; } // r*=0xde88; }
+		buf[p2+(a&255)]^=r;
+		}
+
+	for(a=0,r=0;a<256*2;a++)
+		{
+		if(a<256) { r+=0x455c; r*=0x825d; }
+		else { r+=0xaa4b; } // r*=0xde88; }
+		buf[p2+(a&255)]^=r;
+		}
+
+	for(a=0,r=0;a<256;a++)
+		{
+		r+=0xaa4b; // r*=0xde88;
+		buf[p2+(a&255)]^=r;
+		}
+
+//------------------------------------------------------------------------
+
+	write(f1,buf,sl);
+	chsize(f1,sl);
+	close(f1);
+	return(0);
+	}