1 files changed, 34 insertions, 11 deletions

diff --git a/libc/misc/crypt.c b/libc/misc/crypt.c
index 906dea2..db69325 100644
--- a/libc/misc/crypt.c
+++ b/libc/misc/crypt.c
@@ -1,42 +1,65 @@
-#include <features.h>
-#include <stdlib.h>
 /* TEA based crypt(), version 0.0 <ndf@linux.mit.edu>
  * It looks like there are problems with key bits carrying through
  * to the encryted data, and I want to get rid of that libc call..
  * This is just so rob could see it ;) */
+
+/*
+ * I've:
+ *   Compared the TEA implementation to a reference source - OK
+ *   Noted the cycles count at 64 is twice the suggested value.
+ *   Changed the types of 'n' and 'i' for better code with bcc.
+ *   Removed a possible overrun of rkey by looping the values, it's now
+ *   possible to _choose_ every bit of the 128bit PW with a 32 character word.
+ *   Corrected the output transformation, it lost bits between words.
+ *   Cleaned out all trace of the uncrypted PW from rkey.
+ *
+ *  RDB.
+ */
+
+#include <stdlib.h>
+
 char *
 crypt(const char * key, const char * salt)
 {
-  /* n is the number of rounds, delta is a golden # derivative,
-   k is the key, v is the data to be encrypted. */
-  unsigned long v[2], sum=0, delta=0x9e3779b9, n=64, k[4];
+  /* n is the number of cycles (2 rounds/cycle),
+     delta is a golden # derivative,
+     k is the key, v is the data to be encrypted. */
+
+  unsigned long v[2], sum=0, delta=0x9e3779b9, k[4];
+  int n=64, i, j;
   static char rkey[16];
-  unsigned char i;
 
   /* Our constant string will be a string of zeros .. */
   v[0]=v[1]=k[0]=k[1]=k[2]=k[3]=0;
   for(i=0;i<16;i++) rkey[i]=0;
+
   rkey[0]=*salt;
   rkey[1]=salt[1];
-  for (i=0;key[i];i++) rkey[i+1]=key[i];
+  for (j=2,i=0;key[i];i++,j=((j+1)&15))
+     rkey[j]=(rkey[j]<<4)+(rkey[j]>>4)+ key[i];
+
   memcpy(k, rkey, 4*sizeof(long));
 
-  while (n-->0)  {
+  while (n-->0) {
     sum += delta;
     v[0] += (v[1]<<4)+k[0] ^ v[1]+sum ^ (v[1]>>5)+k[1];
     v[1] += (v[0]<<4)+k[2] ^ v[0]+sum ^ (v[0]>>5)+k[3];
   }
 
+  /* Remove any trace of key */
+  for(i=0;i<16;i++) rkey[i]=0;
   *rkey=*salt; rkey[1]=salt[1];
 
   /* Now we need to unpack the bits and map it to "A-Za-z0-9./" for printing
      in /etc/passwd */
+  sum=v[0];
   for (i=2;i<13;i++)
     {
       /* This unpacks the 6 bit data, each cluster into its own byte */
-      if (i==8) v[0]|=v[1]>>28;
-      rkey[i]=v[(i-2)/6]&0x3F;
-      v[(i-2)/6]>>=6;
+      rkey[i]=(sum&0x3F);
+      sum>>=6;
+      if(i==0+2) sum |= (v[1]<<26);
+      if(i==5+2) sum |= (v[1]>>4);
 
       /* Now we map to the proper chars */
       if (rkey[i]>=0 && rkey[i]<12) rkey[i]+=46;