1 files changed, 98 insertions, 0 deletions
diff --git a/reference/C/CONTRIB/SNIP/crypt.c b/reference/C/CONTRIB/SNIP/crypt.c
new file mode 100755
index 0000000..cbfac15
--- /dev/null
+++ b/reference/C/CONTRIB/SNIP/crypt.c
@@ -0,0 +1,98 @@
+/****************************************************************/
+/*                                                              */
+/*      S-CODER - Encrypt/decrypt data                          */
+/*                                                              */
+/*      Copyright 1987-1989 by Robert B. Stout dba MicroFirm    */
+/*                                                              */
+/*      Originally written by Bob Stout with modifications      */
+/*      suggested by Mike Smedley.                              */
+/*                                                              */
+/*      This code may be used freely in any program for any     */
+/*      application, personal or commercial.                    */
+/*                                                              */
+/*  Current commercial availability:                            */
+/*                                                              */
+/*      1. MicroFirm Toolkit ver 3.00: LYNX and CRYPT utilities */
+/*      2. CXL libraries (MSC, TC, ZTC/C++, PC): fcrypt()       */
+/*         dedicated file encryption function                   */
+/*      3. SMTC & MFLZT libraries: crypt() function             */
+/*                                                              */
+/****************************************************************/
+ 
+char *cryptext;         /* The actual encryption/decryption key */
+int   crypt_ptr = 0;    /* Circular pointer to elements of key  */
+int   crypt_length;     /* Set externally to strlen(cryptext)   */
+ 
+/* NOTES: cryptext should be set and qualified (to something over
+          5-6 chars, minimum) by the calling program, which should
+          also set crypt_ptr in the range of 0 to strlen(cryptext)
+          before each use. If crypt() is used to encrypt several
+          buffers, cryptext should be reloaded and crypt_ptr reset
+          before each buffer is encrypted. The encryption is both
+          reversible - to decrypt data, pass it back through crypt()
+          using the original key and original initial value of
+          crypt_ptr - and multiple passes are commutative.
+*/
+ 
+/**** Encrypt/decrypt buffer datum ******************************/
+void crypt(unsigned char *buf)
+{
+      *buf ^= cryptext[crypt_ptr] ^ (cryptext[0] * crypt_ptr);
+      cryptext[crypt_ptr] += ((crypt_ptr < (crypt_length - 1)) ?
+            cryptext[crypt_ptr + 1] : cryptext[0]);
+      if (!cryptext[crypt_ptr])
+            cryptext[crypt_ptr] += 1;
+      if (++crypt_ptr >= crypt_length)
+            crypt_ptr = 0;
+}
+ 
+/**** Encrypt/decrypt buffer ************************************/
+void bufcrypt(unsigned char *buf, long length)
+{
+      while (length--)
+            crypt(*buf++)
+}
+
+#ifdef TEST
+
+#include <stdio.h>
+#include <string.h>
+
+int main(int argc, char *argv[])
+{
+      static char buf[16384];
+      size_t len, i;
+      FILE *in, *out;
+
+      if (4 > argc)
+      {
+            puts("Usage: CRYPT password infile outfile");
+            return -1;
+      }
+      cryptext = argv[1];
+      crypt_length = strlen(cryptext);
+      if (NULL == (in = fopen(argv[2], "rb")))
+      {
+            printf("Can't open %s for input\n", argv[2]);
+            return -1;
+      }
+      if (NULL == (out = fopen(argv[3], "wb")))
+      {
+            printf("Can't open %s for output\n", argv[3]);
+            return -1;
+      }
+      do
+      {
+            if (0 != (len = fread(buf, 1, 16384, in)))
+            {
+                  for (i = 0; i < len; ++i)
+                        crypt(&buf[i]);
+                  fwrite(buf, 1, len, out);
+            }
+      } while (len);
+      fclose(in);
+      fclose(out);
+      return 0;
+}
+
+#endif