1 #include "os.h"
2 #include <libsec.h>
3 
4 /*
5  *  This MD4 is implemented from the description in Stinson's Cryptography,
6  *  theory and practice. -- presotto
7  */
8 
9 /*
10  *	Rotate ammounts used in the algorithm
11  */
12 enum
13 {
14 	S11=	3,
15 	S12=	7,
16 	S13=	11,
17 	S14=	19,
18 
19 	S21=	3,
20 	S22=	5,
21 	S23=	9,
22 	S24=	13,
23 
24 	S31=	3,
25 	S32=	9,
26 	S33=	11,
27 	S34=	15
28 };
29 
30 typedef struct MD4Table MD4Table;
31 struct MD4Table
32 {
33 	uchar	x;	/* index into data block */
34 	uchar	rot;	/* amount to rotate left by */
35 };
36 
37 static MD4Table tab[] =
38 {
39 	/* round 1 */
40 /*[0]*/	{ 0,	S11},
41 	{ 1,	S12},
42 	{ 2,	S13},
43 	{ 3,	S14},
44 	{ 4,	S11},
45 	{ 5,	S12},
46 	{ 6,	S13},
47 	{ 7,	S14},
48 	{ 8,	S11},
49 	{ 9,	S12},
50 	{ 10,	S13},
51 	{ 11,	S14},
52 	{ 12,	S11},
53 	{ 13,	S12},
54 	{ 14,	S13},
55 	{ 15,	S14},
56 
57 	/* round 2 */
58 /*[16]*/{ 0,	S21},
59 	{ 4,	S22},
60 	{ 8,	S23},
61 	{ 12,	S24},
62 	{ 1,	S21},
63 	{ 5,	S22},
64 	{ 9,	S23},
65 	{ 13,	S24},
66 	{ 2,	S21},
67 	{ 6,	S22},
68 	{ 10,	S23},
69 	{ 14,	S24},
70 	{ 3,	S21},
71 	{ 7,	S22},
72 	{ 11,	S23},
73 	{ 15,	S24},
74 
75 	/* round 3 */
76 /*[32]*/{ 0,	S31},
77 	{ 8,	S32},
78 	{ 4,	S33},
79 	{ 12,	S34},
80 	{ 2,	S31},
81 	{ 10,	S32},
82 	{ 6,	S33},
83 	{ 14,	S34},
84 	{ 1,	S31},
85 	{ 9,	S32},
86 	{ 5,	S33},
87 	{ 13,	S34},
88 	{ 3,	S31},
89 	{ 11,	S32},
90 	{ 7,	S33},
91 	{ 15,	S34},
92 };
93 
94 static void encode(uchar*, u32int*, ulong);
95 static void decode(u32int*, uchar*, ulong);
96 
97 static void
98 md4block(uchar *p, ulong len, MD4state *s)
99 {
100 	int i;
101 	u32int a, b, c, d, tmp;
102 	MD4Table *t;
103 	uchar *end;
104 	u32int x[16];
105 
106 	for(end = p+len; p < end; p += 64){
107 		a = s->state[0];
108 		b = s->state[1];
109 		c = s->state[2];
110 		d = s->state[3];
111 
112 		decode(x, p, 64);
113 
114 		for(i = 0; i < 48; i++){
115 			t = tab + i;
116 			switch(i>>4){
117 			case 0:
118 				a += (b & c) | (~b & d);
119 				break;
120 			case 1:
121 				a += ((b & c) | (b & d) | (c & d)) + 0x5A827999;
122 				break;
123 			case 2:
124 				a += (b ^ c ^ d) + 0x6ED9EBA1;
125 				break;
126 			}
127 			a += x[t->x];
128 			a = (a << t->rot) | (a >> (32 - t->rot));
129 
130 			/* rotate variables */
131 			tmp = d;
132 			d = c;
133 			c = b;
134 			b = a;
135 			a = tmp;
136 		}
137 
138 		s->state[0] += a;
139 		s->state[1] += b;
140 		s->state[2] += c;
141 		s->state[3] += d;
142 
143 		s->len += 64;
144 	}
145 }
146 
147 MD4state*
148 md4(uchar *p, ulong len, uchar *digest, MD4state *s)
149 {
150 	u32int x[16];
151 	uchar buf[128];
152 	int i;
153 	uchar *e;
154 
155 	if(s == nil){
156 		s = malloc(sizeof(*s));
157 		if(s == nil)
158 			return nil;
159 		memset(s, 0, sizeof(*s));
160 		s->malloced = 1;
161 	}
162 
163 	if(s->seeded == 0){
164 		/* seed the state, these constants would look nicer big-endian */
165 		s->state[0] = 0x67452301;
166 		s->state[1] = 0xefcdab89;
167 		s->state[2] = 0x98badcfe;
168 		s->state[3] = 0x10325476;
169 		s->seeded = 1;
170 	}
171 
172 	/* fill out the partial 64 byte block from previous calls */
173 	if(s->blen){
174 		i = 64 - s->blen;
175 		if(len < i)
176 			i = len;
177 		memmove(s->buf + s->blen, p, i);
178 		len -= i;
179 		s->blen += i;
180 		p += i;
181 		if(s->blen == 64){
182 			md4block(s->buf, s->blen, s);
183 			s->blen = 0;
184 		}
185 	}
186 
187 	/* do 64 byte blocks */
188 	i = len & ~0x3f;
189 	if(i){
190 		md4block(p, i, s);
191 		len -= i;
192 		p += i;
193 	}
194 
195 	/* save the left overs if not last call */
196 	if(digest == 0){
197 		if(len){
198 			memmove(s->buf, p, len);
199 			s->blen += len;
200 		}
201 		return s;
202 	}
203 
204 	/*
205 	 *  this is the last time through, pad what's left with 0x80,
206 	 *  0's, and the input count to create a multiple of 64 bytes
207 	 */
208 	if(s->blen){
209 		p = s->buf;
210 		len = s->blen;
211 	} else {
212 		memmove(buf, p, len);
213 		p = buf;
214 	}
215 	s->len += len;
216 	e = p + len;
217 	if(len < 56)
218 		i = 56 - len;
219 	else
220 		i = 120 - len;
221 	memset(e, 0, i);
222 	*e = 0x80;
223 	len += i;
224 
225 	/* append the count */
226 	x[0] = s->len<<3;
227 	x[1] = s->len>>29;
228 	encode(p+len, x, 8);
229 
230 	/* digest the last part */
231 	md4block(p, len+8, s);
232 
233 	/* return result and free state */
234 	encode(digest, s->state, MD4dlen);
235 	if(s->malloced == 1)
236 		free(s);
237 	return nil;
238 }
239 
240 /*
241  *	encodes input (u32int) into output (uchar). Assumes len is
242  *	a multiple of 4.
243  */
244 static void
245 encode(uchar *output, u32int *input, ulong len)
246 {
247 	u32int x;
248 	uchar *e;
249 
250 	for(e = output + len; output < e;) {
251 		x = *input++;
252 		*output++ = x;
253 		*output++ = x >> 8;
254 		*output++ = x >> 16;
255 		*output++ = x >> 24;
256 	}
257 }
258 
259 /*
260  *	decodes input (uchar) into output (u32int). Assumes len is
261  *	a multiple of 4.
262  */
263 static void
264 decode(u32int *output, uchar *input, ulong len)
265 {
266 	uchar *e;
267 
268 	for(e = input+len; input < e; input += 4)
269 		*output++ = input[0] | (input[1] << 8) |
270 			(input[2] << 16) | (input[3] << 24);
271 }