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+/* -*-c-*-
+ *
+ * $Id: mgf.h,v 1.1 2000/06/17 11:33:11 mdw Exp $
+ *
+ * The MGF mask generation function
+ *
+ * (c) 2000 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------* 
+ *
+ * This file is part of Catacomb.
+ *
+ * Catacomb is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ * 
+ * Catacomb is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Library General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Library General Public
+ * License along with Catacomb; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Revision history --------------------------------------------------* 
+ *
+ * $Log: mgf.h,v $
+ * Revision 1.1  2000/06/17 11:33:11  mdw
+ * MGF-1 support, as defined in PKCS#1.
+ *
+ */
+
+/*----- Notes on the MGF-1 mask generating function -----------------------*
+ *
+ * The idea of a mask-generating function is that given an input of arbitrary
+ * size, it can emit a pseudorandom output `mask' of arbitrary size.  This is
+ * used in PKCS#1 OAEP (RFC2437).  My recommendation would be to use a decent
+ * stream cipher instead, like RC4 or SEAL.  MGF-1 isn't very fast.
+ */
+
+#ifndef CATACOMB_MGF_H
+#define CATACOMB_MGF_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/bits.h>
+
+#ifndef CATACOMB_GCIPHER_H
+#  include "gcipher.h"
+#endif
+
+#ifndef CATACOMB_GRAND_H
+#  include "grand.h"
+#endif
+
+/*----- Macros ------------------------------------------------------------*/
+
+#define MGF_DECL(PRE, pre)						\
+									\
+/* --- An MGF generation context --- */					\
+									\
+typedef struct pre##_mgfctx {						\
+  pre##_ctx k;				/* Underlying key context */	\
+  uint32 c;				/* Counter */			\
+  octet buf[PRE##_HASHSZ];		/* Output buffer */		\
+  size_t bsz;				/* Size of buffered data */	\
+} pre##_mgfctx;								\
+									\
+/* --- Other useful constants --- */					\
+									\
+extern const octet pre##_mgfkeysz[];					\
+									\
+/* --- @pre_mgfkeybegin@, @pre_mgfkeyadd@ --- *				\
+ *									\
+ * Arguments:	@pre_mgfctx *k@ = pointer to context to initialize	\
+ *		@const void *p@ = pointer to data to contribute		\
+ *		@size_t sz@ = size of data to contribute		\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		A multi-step keying procedure for initializing an MGF	\
+ *		context.  The data is contributed to a hashing context	\
+ *		which is then used for mask generation.  If you only	\
+ *		have a fixed buffer, you can save a lot of effort by	\
+ *		simply calling @pre_mgfinit@.				\
+ */									\
+									\
+extern void pre##_mgfkeybegin(pre##_mgfctx */*k*/);			\
+extern void pre##_mgfkeyadd(pre##_mgfctx */*k*/,			\
+			    const void */*p*/, size_t /*sz*/);		\
+									\
+/* ---- @pre_mgfinit@ --- *						\
+ *									\
+ * Arguments:	@pre_mgfctx *k@ = pointer to context to initialize	\
+ *		@const void *p@ = pointer to data to contribute		\
+ *		@size_t sz@ = size of data to contribute		\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		A simpler interface to initialization if all of your	\
+ *		keying material is in one place.			\
+ */									\
+									\
+extern void pre##_mgfinit(pre##_mgfctx */*k*/,				\
+			  const void */*p*/, size_t /*sz*/);		\
+									\
+/* --- @pre_mgfencrypt@ --- *						\
+ *									\
+ * Arguments:	@pre_mgfctx *k@ = pointer to masking context		\
+ *		@const void *s@ = pointer to source buffer		\
+ *		@void *d@ = pointer to destination buffer		\
+ *		@size_t sz@ = size of buffers				\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Outputs pseudorandom data, or masks an input buffer.	\
+ *									\
+ *		If @s@ is nonzero, the source material is exclusive-	\
+ *		orred with the generated mask.  If @d@ is zero, the	\
+ *		generator is simply spun around for a while, which	\
+ *		isn't very useful.					\
+ */									\
+									\
+extern void pre##_mgfencrypt(pre##_mgfctx */*k*/, const void */*s*/,	\
+			     void */*d*/, size_t /*sz*/);		\
+									\
+/* --- @pre_mgfsetindex@ --- *						\
+ *									\
+ * Arguments:	@pre_mgfctx *k@ = pointer to masking context		\
+ *		@uint32 *c@ = new index to set				\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Sets a new index.  This may be used to step around the	\
+ *		output stream in a rather crude way.			\
+ */									\
+									\
+extern void pre##_mgfsetindex(pre##_mgfctx */*k*/, uint32 /*c*/);	\
+									\
+/* --- @pre_mgfrand@ --- *						\
+ *									\
+ * Arguments:	@const void *k@ = pointer to key material		\
+ *		@size_t sz@ = size of key material			\
+ *									\
+ * Returns:	Pointer to a generic random number generator instance.	\
+ *									\
+ * Use:		Creates a random number interface wrapper around an	\
+ *		MGF-1-mode hash function.				\
+ */									\
+									\
+extern grand *pre##_mgfrand(const void */*k*/, size_t /*sz*/);		\
+									\
+/* --- Generic cipher interface --- */					\
+									\
+extern const gccipher pre##_mgf;
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif