--- /dev/null
+/* -*-c-*-
+ *
+ * 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.
+ */
+
+/*----- 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
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