xref: /freebsd/usr.bin/enigma/enigma.c (revision dba6dd177bdee890cf445fbe21a5dccefd5de18e)
1 /*
2  *	"enigma.c" is in file cbw.tar from
3  *	anonymous FTP host watmsg.waterloo.edu: pub/crypt/cbw.tar.Z
4  *
5  *	A one-rotor machine designed along the lines of Enigma
6  *	but considerably trivialized.
7  *
8  *	A public-domain replacement for the UNIX "crypt" command.
9  *
10  *	Upgraded to function properly on 64-bit machines.
11  */
12 
13 #include <sys/cdefs.h>
14 __FBSDID("$FreeBSD$");
15 
16 #include <sys/types.h>
17 
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <string.h>
21 #include <unistd.h>
22 
23 #define MINUSKVAR "CrYpTkEy"
24 
25 #define ECHO 010
26 #define ROTORSZ 256
27 #define MASK 0377
28 char	t1[ROTORSZ];
29 char	t2[ROTORSZ];
30 char	t3[ROTORSZ];
31 char	deck[ROTORSZ];
32 char	buf[13];
33 
34 void	shuffle(char *);
35 void	setup(char *);
36 
37 void
38 setup(char *pw)
39 {
40 	int ic, i, k, temp;
41 	char salt[3];
42 	unsigned rnd;
43 	long seed;
44 
45 	strlcpy(salt, pw, sizeof(salt));
46 	memcpy(buf, crypt(pw, salt), sizeof(buf));
47 	seed = 123;
48 	for (i=0; i<13; i++)
49 		seed = seed*buf[i] + i;
50 	for(i=0;i<ROTORSZ;i++) {
51 		t1[i] = i;
52 		deck[i] = i;
53 	}
54 	for(i=0;i<ROTORSZ;i++) {
55 		seed = 5*seed + buf[i%13];
56 		if( sizeof(long) > 4 )  {
57 			/* Force seed to stay in 32-bit signed math */
58 			if( seed & 0x80000000 )
59 				seed = seed | (-1L & ~0xFFFFFFFFL);
60 			else
61 				seed &= 0x7FFFFFFF;
62 		}
63 		rnd = seed % 65521;
64 		k = ROTORSZ-1 - i;
65 		ic = (rnd&MASK)%(k+1);
66 		rnd >>= 8;
67 		temp = t1[k];
68 		t1[k] = t1[ic];
69 		t1[ic] = temp;
70 		if(t3[k]!=0) continue;
71 		ic = (rnd&MASK) % k;
72 		while(t3[ic]!=0) ic = (ic+1) % k;
73 		t3[k] = ic;
74 		t3[ic] = k;
75 	}
76 	for(i=0;i<ROTORSZ;i++)
77 		t2[t1[i]&MASK] = i;
78 }
79 
80 int
81 main(int argc, char *argv[])
82 {
83 	int i, n1, n2, nr1, nr2;
84 	int secureflg = 0, kflag = 0;
85 	char *cp;
86 
87 	if (argc > 1 && argv[1][0] == '-') {
88 		if (argv[1][1] == 's') {
89 			argc--;
90 			argv++;
91 			secureflg = 1;
92 		} else if (argv[1][1] == 'k') {
93 			argc--;
94 			argv++;
95 			kflag = 1;
96 		}
97 	}
98 	if (kflag) {
99 		if ((cp = getenv(MINUSKVAR)) == NULL) {
100 			fprintf(stderr, "%s not set\n", MINUSKVAR);
101 			exit(1);
102 		}
103 		setup(cp);
104 	} else if (argc != 2) {
105 		setup(getpass("Enter key:"));
106 	}
107 	else
108 		setup(argv[1]);
109 	n1 = 0;
110 	n2 = 0;
111 	nr2 = 0;
112 
113 	while((i=getchar()) != -1) {
114 		if (secureflg) {
115 			nr1 = deck[n1]&MASK;
116 			nr2 = deck[nr1]&MASK;
117 		} else {
118 			nr1 = n1;
119 		}
120 		i = t2[(t3[(t1[(i+nr1)&MASK]+nr2)&MASK]-nr2)&MASK]-nr1;
121 		putchar(i);
122 		n1++;
123 		if(n1==ROTORSZ) {
124 			n1 = 0;
125 			n2++;
126 			if(n2==ROTORSZ) n2 = 0;
127 			if (secureflg) {
128 				shuffle(deck);
129 			} else {
130 				nr2 = n2;
131 			}
132 		}
133 	}
134 
135 	return 0;
136 }
137 
138 void
139 shuffle(char deckary[])
140 {
141 	int i, ic, k, temp;
142 	unsigned rnd;
143 	static long seed = 123;
144 
145 	for(i=0;i<ROTORSZ;i++) {
146 		seed = 5*seed + buf[i%13];
147 		rnd = seed % 65521;
148 		k = ROTORSZ-1 - i;
149 		ic = (rnd&MASK)%(k+1);
150 		temp = deckary[k];
151 		deckary[k] = deckary[ic];
152 		deckary[ic] = temp;
153 	}
154 }
155