1 files changed, 62 insertions, 0 deletions
diff --git a/src/lib/crypto/des/f_parity.c b/src/lib/crypto/des/f_parity.c
new file mode 100644
index 000000000..a2e216dca
--- /dev/null
+++ b/src/lib/crypto/des/f_parity.c
@@ -0,0 +1,62 @@
+/*
+ * These routines check and fix parity of encryption keys for the DES
+ * algorithm.
+ *
+ * They are a replacement for routines in key_parity.c, that don't require
+ * the table building that they do.
+ *
+ * Mark Eichin -- Cygnus Support
+ */
+
+#ifndef	lint
+static char rcsid_f_parity_c[] =
+"$Header$";
+#endif	lint
+
+#include "des.h"
+
+/*
+ * des_fixup_key_parity: Forces odd parity per byte; parity is bits
+ *                       8,16,...64 in des order, implies 0, 8, 16, ...
+ *                       vax order.
+ */
+#define smask(step) ((1<<step)-1)
+#define pstep(x,step) (((x)&smask(step))^(((x)>>step)&smask(step)))
+#define parity_char(x) pstep(pstep(pstep((x),4),2),1)
+
+void
+mit_des_fixup_key_parity(key)
+     register des_cblock key;
+{
+    int i;
+    for (i=0; i<sizeof(des_cblock); i++) 
+      {
+	key[i] &= 0xfe;
+	key[i] |= 1^parity_char(key[i]);
+      }
+  
+    return;
+}
+
+/*
+ * des_check_key_parity: returns true iff key has the correct des parity.
+ *                       See des_fix_key_parity for the definition of
+ *                       correct des parity.
+ */
+int
+mit_des_check_key_parity(key)
+     register des_cblock key;
+{
+    int i;
+    
+    for (i=0; i<sizeof(des_cblock); i++) 
+      {
+	if((key[i] & 1) == parity_char(0xfe&key[i])) 
+	  {
+	    return 0;
+	  }
+      }
+
+    return(1);
+}
+