xref: /freebsd/usr.bin/enigma/enigma.c (revision ba00ec3d539f213abbda3a45ef8c539306cac098)
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 static char	t1[ROTORSZ];
29 static char	t2[ROTORSZ];
30 static char	t3[ROTORSZ];
31 static char	deck[ROTORSZ];
32 static char	buf[13];
33 
34 static void	shuffle(char *);
35 static void	setup(char *);
36 
37 static void
38 setup(char *pw)
39 {
40 	int ic, i, k, temp;
41 	char salt[3];
42 	unsigned rnd;
43 	int32_t seed;
44 	char *cryptpw;
45 
46 	strlcpy(salt, pw, sizeof(salt));
47 	cryptpw = crypt(pw, salt);
48 	if (cryptpw == NULL) {
49 		fprintf(stderr, "crypt(3) failure\n");
50 		exit(1);
51 	}
52 	memcpy(buf, cryptpw, sizeof(buf));
53 	seed = 123;
54 	for (i=0; i<13; i++)
55 		seed = seed*buf[i] + i;
56 	for(i=0;i<ROTORSZ;i++) {
57 		t1[i] = i;
58 		deck[i] = i;
59 	}
60 	for(i=0;i<ROTORSZ;i++) {
61 		seed = 5*seed + buf[i%13];
62 		rnd = seed % 65521;
63 		k = ROTORSZ-1 - i;
64 		ic = (rnd&MASK)%(k+1);
65 		rnd >>= 8;
66 		temp = t1[k];
67 		t1[k] = t1[ic];
68 		t1[ic] = temp;
69 		if(t3[k]!=0) continue;
70 		ic = (rnd&MASK) % k;
71 		while(t3[ic]!=0) ic = (ic+1) % k;
72 		t3[k] = ic;
73 		t3[ic] = k;
74 	}
75 	for(i=0;i<ROTORSZ;i++)
76 		t2[t1[i]&MASK] = i;
77 }
78 
79 int
80 main(int argc, char *argv[])
81 {
82 	int i, n1, n2, nr1, nr2;
83 	int secureflg = 0, kflag = 0;
84 	char *cp;
85 
86 	if (argc > 1 && argv[1][0] == '-') {
87 		if (argv[1][1] == 's') {
88 			argc--;
89 			argv++;
90 			secureflg = 1;
91 		} else if (argv[1][1] == 'k') {
92 			argc--;
93 			argv++;
94 			kflag = 1;
95 		}
96 	}
97 	if (kflag) {
98 		if ((cp = getenv(MINUSKVAR)) == NULL) {
99 			fprintf(stderr, "%s not set\n", MINUSKVAR);
100 			exit(1);
101 		}
102 		setup(cp);
103 	} else if (argc != 2) {
104 		setup(getpass("Enter key:"));
105 	}
106 	else
107 		setup(argv[1]);
108 	n1 = 0;
109 	n2 = 0;
110 	nr2 = 0;
111 
112 	while((i=getchar()) != -1) {
113 		if (secureflg) {
114 			nr1 = deck[n1]&MASK;
115 			nr2 = deck[nr1]&MASK;
116 		} else {
117 			nr1 = n1;
118 		}
119 		i = t2[(t3[(t1[(i+nr1)&MASK]+nr2)&MASK]-nr2)&MASK]-nr1;
120 		putchar(i);
121 		n1++;
122 		if(n1==ROTORSZ) {
123 			n1 = 0;
124 			n2++;
125 			if(n2==ROTORSZ) n2 = 0;
126 			if (secureflg) {
127 				shuffle(deck);
128 			} else {
129 				nr2 = n2;
130 			}
131 		}
132 	}
133 
134 	return 0;
135 }
136 
137 static void
138 shuffle(char deckary[])
139 {
140 	int i, ic, k, temp;
141 	unsigned rnd;
142 	static int32_t seed = 123;
143 
144 	for(i=0;i<ROTORSZ;i++) {
145 		seed = 5*seed + buf[i%13];
146 		rnd = seed % 65521;
147 		k = ROTORSZ-1 - i;
148 		ic = (rnd&MASK)%(k+1);
149 		temp = deckary[k];
150 		deckary[k] = deckary[ic];
151 		deckary[ic] = temp;
152 	}
153 }
154