Rearrange the file tree.

[u/mdw/catacomb] / rand / dsarand.h

diff --git a/rand/dsarand.h b/rand/dsarand.h
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+/* -*-c-*-
+ *
+ * Random number generator for DSA
+ *
+ * (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_DSARAND_H
+#define CATACOMB_DSARAND_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/bits.h>
+
+#ifndef CATACOMB_GRAND_H
+#  include "grand.h"
+#endif
+
+#ifndef CATACOMB_SHA_H
+#  include "sha.h"
+#endif
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct dsarand {
+  octet *p;                            /* Pointer to seed (modified) */
+  size_t sz;                           /* Size of the seed buffer */
+  unsigned passes;                     /* Number of passes to make */
+} dsarand;
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @dsarand_init@ --- *
+ *
+ * Arguments:  @dsarand *d@ = pointer to context
+ *             @const void *p@ = pointer to seed buffer
+ *             @size_t sz@ = size of the buffer
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a DSA random number generator.
+ */
+
+extern void dsarand_init(dsarand */*d*/, const void */*p*/, size_t /*sz*/);
+
+/* --- @dsarand_reseed@ --- *
+ *
+ * Arguments:  @dsarand *d@ = pointer to context
+ *             @const void *p@ = pointer to seed buffer
+ *             @size_t sz@ = size of the buffer
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes a DSA random number generator.
+ */
+
+extern void dsarand_reseed(dsarand */*d*/, const void */*p*/, size_t /*sz*/);
+
+/* --- @dsarand_destroy@ --- *
+ *
+ * Arguments:  @dsarand *d@ = pointer to context
+ *
+ * Returns:    ---
+ *
+ * Use:                Disposes of a DSA random number generation context.
+ */
+
+extern void dsarand_destroy(dsarand */*d*/);
+
+/* --- @dsarand_fill@ --- *
+ *
+ * Arguments:  @dsarand *d@ = pointer to context
+ *             @void *p@ = pointer to output buffer
+ *             @size_t sz@ = size of output buffer
+ *
+ * Returns:    ---
+ *
+ * Use:                Fills an output buffer with pseudorandom data.
+ *
+ *             Let %$p$% be the numerical value of the input buffer, and let
+ *             %$b$% be the number of bytes required.  Let
+ *             %$z = \lceil b / 20 \rceil$% be the number of SHA outputs
+ *             required.  Then the output of pass %$n$% is
+ *
+ *               %$P_n = \sum_{0 \le i < z} 2^{160i} SHA(p + nz + i)$%
+ *                                                     %${} \bmod 2^{8b}$%
+ *
+ *             and the actual result in the output buffer is the XOR of all
+ *             of the output passes.
+ *
+ *             The DSA procedure for choosing @q@ involves two passes with
+ *             %$z = 1$%; the procedure for choosing @p@ involves one pass
+ *             with larger %$z$%.  This generalization of the DSA generation
+ *             procedure is my own invention but it seems relatively sound.
+ */
+
+extern void dsarand_fill(dsarand */*d*/, void */*p*/, size_t /*sz*/);
+
+/*----- Generic pseudorandom-number generator interface -------------------*/
+
+/* --- Miscellaneous operations --- */
+
+enum {
+  DSARAND_PASSES = GRAND_SPECIFIC('D'),        /* @unsigned n@ */
+  DSARAND_SEEDSZ,                      /* No args */
+  DSARAND_GETSEED                      /* @void *buf@ */
+};
+
+/* --- @dsarand_create@ --- *
+ *
+ * Arguments:  @const void *p@ = pointer to seed buffer
+ *             @size_t sz@ = size of seed buffer
+ *
+ * Returns:    Pointer to a generic generator.
+ *
+ * Use:                Constructs a generic generator interface to a DSA generator.
+ */
+
+extern grand *dsarand_create(const void */*p*/, size_t /*sz*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif