Add multiply-and-add function for Diffie-Hellman safe prime generation.

[u/mdw/catacomb] / pgen.h

diff --git a/pgen.h b/pgen.h
index 536ba0a..6f2000c 100644 (file)
--- a/pgen.h
+++ b/pgen.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: pgen.h,v 1.1 1999/11/19 13:17:57 mdw Exp $
+ * $Id: pgen.h,v 1.2 1999/11/20 22:23:05 mdw Exp $
  *
  * Finding and testing prime numbers
  *
@@ -30,6 +30,9 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: pgen.h,v $
+ * Revision 1.2  1999/11/20 22:23:05  mdw
+ * Add multiply-and-add function for Diffie-Hellman safe prime generation.
+ *
  * Revision 1.1  1999/11/19 13:17:57  mdw
  * Prime number generator and tester.
  *
@@ -108,6 +111,26 @@ extern void pgen_destroy(pgen */*p*/);
 
 extern int pgen_step(pgen */*p*/, mpw /*step*/);
 
+/* --- @pgen_muladd@ --- *
+ *
+ * Arguments:  @pgen *p@ = destination prime generation context
+ *             @const pgen *q@ = source prime generation context
+ *             @mpw m@ = number to multiply by
+ *             @mpw a@ = number to add
+ *
+ * Returns:    One of the @PGEN@ constants above.
+ *
+ * Use:                Multiplies the number in a prime generation context by a
+ *             small value and then adds a small value.  The destination
+ *             should either be uninitialized or the same as the source.
+ *
+ *             Common things to do include multiplying by 2 and adding 0 to
+ *             turn a prime into a jump for finding other primes with @q@ as
+ *             a factor of @p - 1@, or multiplying by 2 and adding 1.
+ */
+
+extern int pgen_muladd(pgen */*p*/, const pgen */*q*/, mpw /*m*/, mpw /*a*/);
+
 /* --- @pgen_jump@ --- *
  *
  * Arguments:  @pgen *p@ = pointer to prime generation context