--- /dev/null
+/* -*-c-*-
+ *
+ * Output feedback for block ciphers
+ *
+ * (c) 1999 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_OFB_H
+#define CATACOMB_OFB_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 ------------------------------------------------------------*/
+
+/* --- @OFB_DECL@ --- *
+ *
+ * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
+ *
+ * Use: Makes declarations for output feedback mode.
+ */
+
+#define OFB_DECL(PRE, pre) \
+ \
+/* --- Output feedback context --- */ \
+ \
+typedef struct pre##_ofbctx { \
+ pre##_ctx ctx; /* Underlying cipher context */ \
+ unsigned off; /* Current offset in buffer */ \
+ octet iv[PRE##_BLKSZ]; /* Output buffer and IV */ \
+} pre##_ofbctx; \
+ \
+/* --- @pre_ofbgetiv@ --- * \
+ * \
+ * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \
+ * @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##_ofbgetiv(const pre##_ofbctx */*ctx*/, \
+ void */*iv*/); \
+ \
+/* --- @pre_ofbsetiv@ --- * \
+ * \
+ * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
+ * @cnost void *iv@ = pointer to IV to set \
+ * \
+ * Returns: --- \
+ * \
+ * Use: Sets the IV to use for subsequent encryption. \
+ */ \
+ \
+extern void pre##_ofbsetiv(pre##_ofbctx */*ctx*/, \
+ const void */*iv*/); \
+ \
+/* --- @pre_ofbbdry@ --- * \
+ * \
+ * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
+ * \
+ * Returns: --- \
+ * \
+ * Use: Inserts a boundary during encryption. Successful \
+ * decryption must place a similar boundary. \
+ */ \
+ \
+extern void pre##_ofbbdry(pre##_ofbctx */*ctx*/); \
+ \
+/* --- @pre_ofbsetkey@ --- * \
+ * \
+ * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
+ * @const pre_ctx *k@ = pointer to cipher context \
+ * \
+ * Returns: --- \
+ * \
+ * Use: Sets the OFB context to use a different cipher key. \
+ */ \
+ \
+extern void pre##_ofbsetkey(pre##_ofbctx */*ctx*/, \
+ const pre##_ctx */*k*/); \
+ \
+/* --- @pre_ofbinit@ --- * \
+ * \
+ * Arguments: @pre_ofbctx *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 OFB 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_ofbsetkey@ \
+ * and @pre_ofbsetiv@. \
+ */ \
+ \
+extern void pre##_ofbinit(pre##_ofbctx */*ctx*/, \
+ const void */*key*/, size_t /*sz*/, \
+ const void */*iv*/); \
+ \
+/* --- @pre_ofbencrypt@ --- * \
+ * \
+ * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \
+ * @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 OFB \
+ * mode: encryption and decryption are the same in OFB. \
+ * 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##_ofbencrypt(pre##_ofbctx */*ctx*/, \
+ const void */*src*/, void */*dest*/, \
+ size_t /*sz*/); \
+ \
+/* --- @pre_ofbrand@ --- * \
+ * \
+ * 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 \
+ * OFB-mode block cipher. \
+ */ \
+ \
+extern grand *pre##_ofbrand(const void */*k*/, size_t /*sz*/); \
+ \
+/* --- Generic cipher interface --- */ \
+ \
+extern const gccipher pre##_ofb;
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+ }
+#endif
+
+#endif
projects / u / mdw / catacomb / blobdiff