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	md5.c - 9base - revived minimalist port of Plan 9 userland to Unix
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	md5.c (3254B)
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	1 #include "os.h"
	2 #include <libsec.h>
	3
	4 /*
	5 * rfc1321 requires that I include this. The code is new. The constan…
	6 * all come from the rfc (hence the copyright). We trade a table for t…
	7 * macros in rfc. The total size is a lot less. -- presotto
	8 *
	9 * Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
	10 * rights reserved.
	11 *
	12 * License to copy and use this software is granted provided that…
	13 * is identified as the "RSA Data Security, Inc. MD5 Message-Dige…
	14 * Algorithm" in all material mentioning or referencing this soft…
	15 * or this function.
	16 *
	17 * License is also granted to make and use derivative works provi…
	18 * that such works are identified as "derived from the RSA Data
	19 * Security, Inc. MD5 Message-Digest Algorithm" in all material
	20 * mentioning or referencing the derived work.
	21 *
	22 * RSA Data Security, Inc. makes no representations concerning ei…
	23 * the merchantability of this software or the suitability of this
	24 * software forany particular purpose. It is provided "as is"
	25 * without express or implied warranty of any kind.
	26 * These notices must be retained in any copies of any part of th…
	27 * documentation and/or software.
	28 */
	29
	30 static void encode(uchar, u32int, ulong);
	31
	32 extern void _md5block(uchar, ulong, u32int);
	33
	34 MD5state*
	35 md5(uchar p, ulong len, uchar digest, MD5state *s)
	36 {
	37 u32int x[16];
	38 uchar buf[128];
	39 int i;
	40 uchar *e;
	41
	42 if(s == nil){
	43 s = malloc(sizeof(*s));
	44 if(s == nil)
	45 return nil;
	46 memset(s, 0, sizeof(*s));
	47 s->malloced = 1;
	48 }
	49
	50 if(s->seeded == 0){
	51 /* seed the state, these constants would look nicer big-…
	52 s->state[0] = 0x67452301;
	53 s->state[1] = 0xefcdab89;
	54 s->state[2] = 0x98badcfe;
	55 s->state[3] = 0x10325476;
	56 s->seeded = 1;
	57 }
	58
	59 /* fill out the partial 64 byte block from previous calls */
	60 if(s->blen){
	61 i = 64 - s->blen;
	62 if(len < i)
	63 i = len;
	64 memmove(s->buf + s->blen, p, i);
	65 len -= i;
	66 s->blen += i;
	67 p += i;
	68 if(s->blen == 64){
	69 _md5block(s->buf, s->blen, s->state);
	70 s->len += s->blen;
	71 s->blen = 0;
	72 }
	73 }
	74
	75 /* do 64 byte blocks */
	76 i = len & ~0x3f;
	77 if(i){
	78 _md5block(p, i, s->state);
	79 s->len += i;
	80 len -= i;
	81 p += i;
	82 }
	83
	84 /* save the left overs if not last call */
	85 if(digest == 0){
	86 if(len){
	87 memmove(s->buf, p, len);
	88 s->blen += len;
	89 }
	90 return s;
	91 }
	92
	93 /*
	94 * this is the last time through, pad what's left with 0x80,
	95 * 0's, and the input count to create a multiple of 64 bytes
	96 */
	97 if(s->blen){
	98 p = s->buf;
	99 len = s->blen;
	100 } else {
	101 memmove(buf, p, len);
	102 p = buf;
	103 }
	104 s->len += len;
	105 e = p + len;
	106 if(len < 56)
	107 i = 56 - len;
	108 else
	109 i = 120 - len;
	110 memset(e, 0, i);
	111 *e = 0x80;
	112 len += i;
	113
	114 /* append the count */
	115 x[0] = s->len<<3;
	116 x[1] = s->len>>29;
	117 encode(p+len, x, 8);
	118
	119 /* digest the last part */
	120 _md5block(p, len+8, s->state);
	121 s->len += len;
	122
	123 /* return result and free state */
	124 encode(digest, s->state, MD5dlen);
	125 if(s->malloced == 1)
	126 free(s);
	127 return nil;
	128 }
	129
	130 /*
	131 * encodes input (u32int) into output (uchar). Assumes len is
	132 * a multiple of 4.
	133 */
	134 static void
	135 encode(uchar output, u32int input, ulong len)
	136 {
	137 u32int x;
	138 uchar *e;
	139
	140 for(e = output + len; output < e;) {
	141 x = *input++;
	142 *output++ = x;
	143 *output++ = x >> 8;
	144 *output++ = x >> 16;
	145 *output++ = x >> 24;
	146 }
	147 }