X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/symm/counter.h

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+/* -*-c-*-
+ *
+ * Block cipher counter mode (or long cycle mode)
+ *
+ * (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.
+ */
+
+#ifndef CATACOMB_COUNTER_H
+#define CATACOMB_COUNTER_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <stddef.h>
+
+#include <mLib/bits.h>
+
+#ifndef CATACOMB_GCIPHER_H
+#  include "gcipher.h"
+#endif
+
+#ifndef CATACOMB_GRAND_H
+#  include "grand.h"
+#endif
+
+/*----- Macros ------------------------------------------------------------*/
+
+/* --- @COUNTER_DECL@ --- *
+ *
+ * Arguments:	@PRE@, @pre@ = prefixes for block cipher definitions
+ *
+ * Use:		Makes declarations for counter mode.
+ */
+
+#define COUNTER_DECL(PRE, pre)						\
+									\
+/* --- Counter mode context --- */					\
+									\
+typedef struct pre##_counterctx {					\
+  pre##_ctx ctx;			/* Underlying cipher context */	\
+  unsigned off;				/* Current offset in buffer */	\
+  octet buf[PRE##_BLKSZ];		/* Output buffer */		\
+  uint32 n[PRE##_BLKSZ / 4];		/* Counter */			\
+} pre##_counterctx;							\
+									\
+/* --- @pre_countergetiv@ --- *						\
+ *									\
+ * Arguments:	@const pre_counterctx *ctx@ = pointer to counter	\
+ *			context						\
+ *		@void *iv@ = pointer to output data block		\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Reads the currently set IV.  Reading and setting an IV	\
+ *		is not transparent to the cipher.  It will add a `step'	\
+ *		which must be matched by a similar operation during	\
+ *		decryption.						\
+ */									\
+									\
+extern void pre##_countergetiv(const pre##_counterctx */*ctx*/,		\
+			       void */*iv*/);				\
+									\
+/* --- @pre_countersetiv@ --- *						\
+ *									\
+ * Arguments:	@pre_counterctx *ctx@ = pointer to counter context	\
+ *		@cnost void *iv@ = pointer to IV to set			\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Sets the IV to use for subsequent encryption.		\
+ */									\
+									\
+extern void pre##_countersetiv(pre##_counterctx */*ctx*/,		\
+			       const void */*iv*/);			\
+									\
+/* --- @pre_counterbdry@ --- *						\
+ *									\
+ * Arguments:	@pre_counterctx *ctx@ = pointer to counter context	\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Inserts a boundary during encryption.  Successful	\
+ *		decryption must place a similar boundary.		\
+ */									\
+									\
+extern void pre##_counterbdry(pre##_counterctx */*ctx*/);		\
+									\
+/* --- @pre_countersetkey@ --- *					\
+ *									\
+ * Arguments:	@pre_counterctx *ctx@ = pointer to counter context	\
+ *		@const pre_ctx *k@ = pointer to cipher context		\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Sets the counter context to use a different cipher key.	\
+ */									\
+									\
+extern void pre##_countersetkey(pre##_counterctx */*ctx*/,		\
+				const pre##_ctx */*k*/);		\
+									\
+/* --- @pre_counterinit@ --- *						\
+ *									\
+ * Arguments:	@pre_counterctx *ctx@ = pointer to cipher context	\
+ *		@const void *key@ = pointer to the key buffer		\
+ *		@size_t sz@ = size of the key				\
+ *		@const void *iv@ = pointer to initialization vector	\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Initializes a counter context ready for use.  You	\
+ *		should ensure that the IV chosen is unique: reusing an	\
+ *		IV will compromise the security of the entire		\
+ *		plaintext.  This is equivalent to calls to @pre_init@,	\
+ *		@pre_countersetkey@ and @pre_countersetiv@.		\
+ */									\
+									\
+extern void pre##_counterinit(pre##_counterctx */*ctx*/,		\
+			      const void */*key*/, size_t /*sz*/,	\
+			      const void */*iv*/);			\
+									\
+/* --- @pre_counterencrypt@ --- *					\
+ *									\
+ * Arguments:	@pre_counterctx *ctx@ = pointer to counter context	\
+ *		@const void *src@ = pointer to source data		\
+ *		@void *dest@ = pointer to destination data		\
+ *		@size_t sz@ = size of block to be encrypted		\
+ *									\
+ * Returns:	---							\
+ *									\
+ * Use:		Encrypts or decrypts a block with a block cipher in	\
+ *		counter mode: encryption and decryption are the same in	\
+ *		counter.  The destination may be null to just churn the	\
+ *		feedback round for a bit.  The source may be null to	\
+ *		use the cipher as a random data generator.		\
+ */									\
+									\
+extern void pre##_counterencrypt(pre##_counterctx */*ctx*/,		\
+				 const void */*src*/, void */*dest*/,	\
+				 size_t /*sz*/);			\
+									\
+/* --- @pre_counterrand@ --- *						\
+ *									\
+ * Arguments:	@const void *k@ = pointer to key material		\
+ *		@size_t sz@ = size of key material			\
+ *									\
+ * Returns:	Pointer to generic random number generator interface.	\
+ *									\
+ * Use:		Creates a random number interface wrapper around an	\
+ *		counter-mode block cipher.				\
+ */									\
+									\
+extern grand *pre##_counterrand(const void */*k*/, size_t /*sz*/);	\
+									\
+/* --- Generic cipher interface --- */					\
+									\
+extern const gccipher pre##_counter;
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif