This is enigma, aka. crypt(1). It has suppsedly been taken from

Cryptbreakers Workbench.  While arguably a rather weak encryption,
it's in some use in the Internet still, and provided by a bunch of
other Unix systesms, so we include it here for compatibility.

Silently agreed by: core

usr.bin/enigma/Makefile

@@ -0,0 +1,9 @@
+all:	enigma makekey
+
+install:	enigma makekey
+	cp enigma makekey /usr/brlcad/bin/.
+	cp makekey.8 /usr/brlcad/man/man1/.
+	ln -s enigma /usr/brlcad/bin/crypt
+
+clean:
+	rm -f enigma makekey *.o

usr.bin/enigma/enigma.c

@@ -0,0 +1,173 @@
+/*
+ *	"enigma.c" is in file cbw.tar from
+ *	anonymous FTP host watmsg.waterloo.edu: pub/crypt/cbw.tar.Z
+ *
+ *	A one-rotor machine designed along the lines of Enigma
+ *	but considerably trivialized.
+ *
+ *	A public-domain replacement for the UNIX "crypt" command.
+ *
+ *	Upgraded to function properly on 64-bit machines.
+ */
+
+#define ECHO 010
+#include <stdio.h>
+#define ROTORSZ 256
+#define MASK 0377
+char	t1[ROTORSZ];
+char	t2[ROTORSZ];
+char	t3[ROTORSZ];
+char	deck[ROTORSZ];
+char	*getpass();
+char	buf[13];
+
+void	shuffle();
+void	puth();
+
+void
+setup(pw)
+char *pw;
+{
+	int ic, i, k, temp, pf[2], pid;
+	unsigned random;
+	long seed;
+
+	strncpy(buf, pw, 8);
+	while (*pw)
+		*pw++ = '\0';
+	buf[8] = buf[0];
+	buf[9] = buf[1];
+	pipe(pf);
+	if ((pid=fork())==0) {
+		close(0);
+		close(1);
+		dup(pf[0]);
+		dup(pf[1]);
+		execlp("makekey", "-", 0);
+		execl("/usr/libexec/makekey", "-", 0);	/* BSDI */
+		execl("/usr/lib/makekey", "-", 0);
+		execl("/usr/bin/makekey", "-", 0);	/* IBM */
+		execl("/lib/makekey", "-", 0);
+		perror("makekey");
+		fprintf(stderr, "enigma: cannot execute 'makekey', aborting\n");
+		exit(1);
+	}
+	write(pf[1], buf, 10);
+	close(pf[1]);
+	i=wait((int *)NULL);
+	if (i<0) perror("enigma: wait");
+	if (i!=pid) {
+		fprintf(stderr, "enigma: expected pid %d, got pid %d\n", pid, i);
+		exit(1);
+	}
+	if ((i=read(pf[0], buf, 13)) != 13) {
+		fprintf(stderr, "enigma: cannot generate key, read %d\n",i);
+		exit(1);
+	}
+	seed = 123;
+	for (i=0; i<13; i++)
+		seed = seed*buf[i] + i;
+	for(i=0;i<ROTORSZ;i++) {
+		t1[i] = i;
+		deck[i] = i;
+	}
+	for(i=0;i<ROTORSZ;i++) {
+		seed = 5*seed + buf[i%13];
+		if( sizeof(long) > 4 )  {
+			/* Force seed to stay in 32-bit signed math */
+			if( seed & 0x80000000 )
+				seed = seed | (-1L & ~0xFFFFFFFFL);
+			else
+				seed &= 0x7FFFFFFF;
+		}
+		random = seed % 65521;
+		k = ROTORSZ-1 - i;
+		ic = (random&MASK)%(k+1);
+		random >>= 8;
+		temp = t1[k];
+		t1[k] = t1[ic];
+		t1[ic] = temp;
+		if(t3[k]!=0) continue;
+		ic = (random&MASK) % k;
+		while(t3[ic]!=0) ic = (ic+1) % k;
+		t3[k] = ic;
+		t3[ic] = k;
+	}
+	for(i=0;i<ROTORSZ;i++)
+		t2[t1[i]&MASK] = i;
+}
+
+main(argc, argv)
+char *argv[];
+{
+	register int i, n1, n2, nr1, nr2;
+	int secureflg = 0;
+
+	if (argc > 1 && argv[1][0] == '-' && argv[1][1] == 's') {
+		argc--;
+		argv++;
+		secureflg = 1;
+	}
+	if (argc != 2){
+		setup(getpass("Enter key:"));
+	}
+	else
+		setup(argv[1]);
+	n1 = 0;
+	n2 = 0;
+	nr2 = 0;
+
+	while((i=getchar()) >=0) {
+		if (secureflg) {
+			nr1 = deck[n1]&MASK;
+			nr2 = deck[nr1]&MASK;
+		} else {
+			nr1 = n1;
+		}
+		i = t2[(t3[(t1[(i+nr1)&MASK]+nr2)&MASK]-nr2)&MASK]-nr1;
+		putchar(i);
+		n1++;
+		if(n1==ROTORSZ) {
+			n1 = 0;
+			n2++;
+			if(n2==ROTORSZ) n2 = 0;
+			if (secureflg) {
+				shuffle(deck);
+			} else {
+				nr2 = n2;
+			}
+		}
+	}
+}
+
+void
+shuffle(deck)
+	char deck[];
+{
+	int i, ic, k, temp;
+	unsigned random;
+	static long seed = 123;
+
+	for(i=0;i<ROTORSZ;i++) {
+		seed = 5*seed + buf[i%13];
+		random = seed % 65521;
+		k = ROTORSZ-1 - i;
+		ic = (random&MASK)%(k+1);
+		temp = deck[k];
+		deck[k] = deck[ic];
+		deck[ic] = temp;
+	}
+}
+
+void
+puth( title, cp, len )
+char	*title;
+char	*cp;
+int	len;
+{
+	fprintf( stderr, "%s = ", title);
+	while( len-- > 0 )  {
+		fprintf(stderr, "%2.2x ", (*cp++) & 0xFF );
+	}
+	fprintf(stderr,"\n");
+}