steal from krb4 and fix

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@6855 ec53bebd-3082-4978-b11e-865c3cabbd6b

kadmin/random_password.c

@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 1998, 1999 Kungliga Tekniska H<>gskolan
+ * (Royal Institute of Technology, Stockholm, Sweden). 
+ * All rights reserved. 
+ *
+ * Redistribution and use in source and binary forms, with or without 
+ * modification, are permitted provided that the following conditions 
+ * are met: 
+ *
+ * 1. Redistributions of source code must retain the above copyright 
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright 
+ *    notice, this list of conditions and the following disclaimer in the 
+ *    documentation and/or other materials provided with the distribution. 
+ *
+ * 3. All advertising materials mentioning features or use of this software 
+ *    must display the following acknowledgement: 
+ *      This product includes software developed by Kungliga Tekniska 
+ *      H<>gskolan and its contributors. 
+ *
+ * 4. Neither the name of the Institute nor the names of its contributors 
+ *    may be used to endorse or promote products derived from this software 
+ *    without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
+ * SUCH DAMAGE. 
+ */
+
+#include "kadmin_locl.h"
+
+RCSID("$Id$");
+
+/* This file defines some a function that generates a random password,
+   that can be used when creating a large amount of principals (such
+   as for a batch of students). Since this is a political matter, you
+   should think about how secure generated passwords has to be.
+   
+   Both methods defined here will give you at least 55 bits of
+   entropy.
+   */
+
+/* If you want OTP-style passwords, define OTP_STYLE */
+
+#ifdef OTP_STYLE
+#include <otp.h>
+#else
+static void generate_password(char **pw, int num_classes, ...);
+#endif
+
+void
+random_password(char *pw, size_t len)
+{
+#ifdef OTP_STYLE
+    {
+	des_cblock newkey;
+
+	des_new_random_key(&newkey);
+	otp_print_stddict (newkey, pw, len);
+	strlwr(pw);
+    }
+#else
+    char *pass;
+    generate_password(&pass, 3, 
+		      "abcdefghijklmnopqrstuvwxyz", 7, 
+		      "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 2, 
+		      "@$%&*()-+=:,/<>1234567890", 1);
+    strcpy_truncate(pw, pass, len);
+    memset(pass, 0, strlen(pass));
+    free(pass);
+#endif
+}
+
+/* some helper functions */
+
+#ifndef OTP_STYLE
+/* return a random value in range 0-127 */
+static int
+RND(des_cblock *key, int *left)
+{
+    if(*left == 0){
+	des_new_random_key(key);
+	*left = 8;
+    }
+    (*left)--;
+    return ((unsigned char*)key)[*left];
+}
+
+/* This a helper function that generates a random password with a
+   number of characters from a set of character classes.
+
+   If there are n classes, and the size of each class is Pi, and the
+   number of characters from each class is Ni, the number of possible
+   passwords are (given that the character classes are disjoint):
+
+     n             n
+   -----        /  ----  \
+   |   |  Ni    |  \     |
+   |   | Pi     |   \  Ni| !
+   |   | ---- * |   /    |
+   |   | Ni!    |  /___  |
+    i=1          \  i=1  /
+   
+    Since it uses the RND function above, neither the size of each
+    class, nor the total length of the generated password should be
+    larger than 127 (without fixing RND).
+   
+   */
+static void
+generate_password(char **pw, int num_classes, ...)
+{
+    struct {
+	const char *str;
+	int len;
+	int freq;
+    } *classes;
+    va_list ap;
+    int len, i;
+    des_cblock rbuf; /* random buffer */
+    int rleft = 0;
+
+    classes = malloc(num_classes * sizeof(*classes));
+    va_start(ap, num_classes);
+    len = 0;
+    for(i = 0; i < num_classes; i++){
+	classes[i].str = va_arg(ap, const char*);
+	classes[i].len = strlen(classes[i].str);
+	classes[i].freq = va_arg(ap, int);
+	len += classes[i].freq;
+    }
+    va_end(ap);
+    *pw = malloc(len + 1);
+    if(*pw == NULL)
+	return;
+    for(i = 0; i < len; i++) {
+	int j;
+	int x = RND(&rbuf, &rleft) % (len - i);
+	int t = 0;
+	for(j = 0; j < num_classes; j++) {
+	    if(x < t + classes[j].freq) {
+		(*pw)[i] = classes[j].str[RND(&rbuf, &rleft) % classes[j].len];
+		classes[j].freq--;
+		break;
+	    }
+	    t += classes[j].freq;
+	}
+    }
+    (*pw)[len] = '\0';
+    memset(rbuf, 0, sizeof(rbuf));
+    free(classes);
+}
+#endif