Support for Optimal Asymmetric Encryption Padding.

diff --git a/oaep.c b/oaep.c
new file mode 100644 (file)
index 0000000..0e135f2
--- /dev/null
+++ b/oaep.c
@@ -0,0 +1,192 @@
+/* -*-c-*-
+ *
+ * $Id: oaep.c,v 1.1 2000/07/01 11:18:30 mdw Exp $
+ *
+ * Optimal asymmetric encryption packing
+ *
+ * (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: oaep.c,v $
+ * Revision 1.1  2000/07/01 11:18:30  mdw
+ * Support for Optimal Asymmetric Encryption Padding.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <string.h>
+
+#include <mLib/alloc.h>
+#include <mLib/bits.h>
+#include <mLib/dstr.h>
+
+#include "gcipher.h"
+#include "ghash.h"
+#include "grand.h"
+#include "oaep.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @oaep_encode@ --- *
+ *
+ * Arguments:  @const void *msg@ = pointer to message data
+ *             @size_t msz@ = size of message data
+ *             @void *buf@ = pointer to output buffer
+ *             @size_t sz@ = size of the output buffer
+ *             @void *p@ = pointer to OAEP parameter block
+ *
+ * Returns:    Zero if all went well, negative on failure.
+ *
+ * Use:                Implements the operation @EME-OAEP-ENCODE@, as defined in
+ *             PKCS#1 v. 2.0 (RFC2437).
+ */
+
+int oaep_encode(const void *msg, size_t msz, void *buf, size_t sz, void *p)
+{
+  oaep *o = p;
+  size_t hsz = o->ch->hashsz;
+  ghash *h = o->ch->init();
+  octet *q, *mq, *qq;
+  octet *pp;
+  gcipher *c;
+  size_t n;
+
+  /* --- Ensure that everything is sensibly sized --- */
+
+  if (2 * hsz + 2 + msz > sz)
+    return (-1);
+
+  /* --- Make the `seed' value --- */
+
+  q = buf;
+  *q++ = 0; sz--;
+  mq = q + hsz;
+  qq = q + sz;
+  o->r->ops->fill(o->r, q, hsz);
+
+  /* --- Fill in the rest of the buffer --- */
+
+  h->ops->hash(h, o->ep, o->epsz);
+  h->ops->done(h, mq);
+  h->ops->destroy(h);
+  pp = mq + hsz;
+  n = sz - 2 * hsz - msz - 1;
+  memset(pp, 0, n);
+  pp += n;
+  *pp++ = 1;
+  memcpy(pp, msg, msz);
+
+  /* --- Do the packing --- */
+
+  n = sz - hsz;
+  c = o->cc->init(q, hsz);
+  c->ops->encrypt(c, mq, mq, n);
+  c->ops->destroy(c);
+
+  c = o->cc->init(mq, n);
+  c->ops->encrypt(c, q, q, hsz);
+  c->ops->destroy(c);
+
+  /* --- Done --- */
+
+  return (0);
+}
+
+/* --- @oaep_decode@ --- *
+ *
+ * Arguments:  @const void *buf@ = pointer to encoded buffer
+ *             @size_t sz@ = size of the encoded buffer
+ *             @dstr *d@ = pointer to destination string
+ *             @void *p@ = pointer to OAEP parameter block
+ *
+ * Returns:    The length of the output string if successful, negative on
+ *             failure.
+ *
+ * Use:                Implements the operation @EME-OAEP-DECODE@, as defined in
+ *             PKCS#1 v. 2.0 (RFC2437).
+ */
+
+int oaep_decode(const void *buf, size_t sz, dstr *d, void *p)
+{
+  oaep *o = p;
+  gcipher *c;
+  ghash *h;
+  octet *q, *mq, *qq;
+  octet *pp;
+  size_t n;
+  size_t hsz = o->ch->hashsz;
+  int rc = -1;
+
+  /* --- Ensure that the block is large enough --- */
+
+  if (sz < 2 * hsz)
+    return (-1);
+
+  q = x_alloc(d->a, sz);
+  memcpy(q, buf, sz);
+
+  /* --- Decrypt the message --- */
+
+  if (*q != 0)
+    goto fail;
+  q++; sz--;
+  mq = q + hsz;
+  qq = q + sz;
+  n = sz - hsz;
+  c = o->cc->init(mq, n);
+  c->ops->decrypt(c, q, q, hsz);
+  c->ops->destroy(c);
+
+  c = o->cc->init(q, hsz);
+  c->ops->decrypt(c, mq, mq, n);
+  c->ops->destroy(c);
+  q--;
+
+  /* --- Check the hash on the encoding parameters --- */
+
+  h = o->ch->init();
+  h->ops->hash(h, o->ep, o->epsz);
+  h->ops->done(h, q);
+  if (memcmp(q, mq, hsz) != 0)
+    goto fail;
+
+  /* --- Now find the start of the actual message --- */
+
+  pp = mq + hsz;
+  while (*pp == 0 && pp < qq)
+    pp++;
+  if (pp >= qq || *pp++ != 1)
+    return (-1);
+  n = qq - pp;
+  dstr_putm(d, pp, n);
+  rc = n;
+
+fail:
+  x_free(d->a, q);
+  return (rc);
+}
+
+/*----- That's all, folks -------------------------------------------------*/

diff --git a/oaep.h b/oaep.h
new file mode 100644 (file)
index 0000000..3f956b6
--- /dev/null
+++ b/oaep.h
@@ -0,0 +1,123 @@
+/* -*-c-*-
+ *
+ * $Id: oaep.h,v 1.1 2000/07/01 11:18:30 mdw Exp $
+ *
+ * Optimal asymmetric encryption packing
+ *
+ * (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: oaep.h,v $
+ * Revision 1.1  2000/07/01 11:18:30  mdw
+ * Support for Optimal Asymmetric Encryption Padding.
+ *
+ */
+
+/*----- Notes on OAEP -----------------------------------------------------*
+ *
+ * Applying OAEP before RSA encryption renders the construction plaintext-
+ * aware under the random oracle model.  This is probably a good thing.  OAEP
+ * was designed by Bellare and Rogaway.  This particular variant is the one
+ * specified in PKCS#1 version 2.0.  It's apparently not compatible with the
+ * OAEP used in the SET protocols.
+ */
+
+#ifndef CATACOMB_OAEP_H
+#define CATACOMB_OAEP_H
+
+#ifdef __cplusplus
+  extern "C" {
+#endif
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/bits.h>
+#include <mLib/dstr.h>
+
+#ifndef CATACOMB_GCIPHER_H
+#  include "gcipher.h"
+#endif
+
+#ifndef CATACOMB_GHASH_H
+#  include "ghash.h"
+#endif
+
+#ifndef CATACOMB_GRAND_H
+#  include "grand.h"
+#endif
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct oaep {
+  const gccipher *cc;                  /* Cipher class for masking */
+  const gchash *ch;                    /* Hash class for parameter block */
+  grand *r;                            /* Random number source */
+  const void *ep;                      /* Encoding parameters block */
+  size_t epsz;                         /* Size of the parameter block */
+} oaep;
+
+/*----- Functions provided ------------------------------------------------*/
+
+/* --- @oaep_encode@ --- *
+ *
+ * Arguments:  @const void *msg@ = pointer to message data
+ *             @size_t msz@ = size of message data
+ *             @void *buf@ = pointer to output buffer
+ *             @size_t sz@ = size of the output buffer
+ *             @void *p@ = pointer to OAEP parameter block
+ *
+ * Returns:    Zero if all went well, negative on failure.
+ *
+ * Use:                Implements the operation @EME-OAEP-ENCODE@, as defined in
+ *             PKCS#1 v. 2.0 (RFC2437).
+ */
+
+extern int oaep_encode(const void */*msg*/, size_t /*msz*/,
+                      void */*buf*/, size_t /*sz*/, void */*p*/);
+
+/* --- @oaep_decode@ --- *
+ *
+ * Arguments:  @const void *buf@ = pointer to encoded buffer
+ *             @size_t sz@ = size of the encoded buffer
+ *             @dstr *d@ = pointer to destination string
+ *             @void *p@ = pointer to OAEP parameter block
+ *
+ * Returns:    The length of the output string if successful, negative on
+ *             failure.
+ *
+ * Use:                Implements the operation @EME-OAEP-DECODE@, as defined in
+ *             PKCS#1 v. 2.0 (RFC2437).
+ */
+
+extern int oaep_decode(const void */*buf*/, size_t /*sz*/,
+                      dstr */*d*/, void */*p*/);
+
+/*----- That's all, folks -------------------------------------------------*/
+
+#ifdef __cplusplus
+  }
+#endif
+
+#endif