Public-key operations, for symmetry with `rsa-priv.c'. Functions for

doing padded RSA encryption and signature verification.

diff --git a/rsa-pub.c b/rsa-pub.c
new file mode 100644 (file)
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--- /dev/null
+++ b/rsa-pub.c
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+/* -*-c-*-
+ *
+ * $Id: rsa-pub.c,v 1.1 2000/07/01 11:23:52 mdw Exp $
+ *
+ * [RSA encryption with padding *
+ * (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: rsa-pub.c,v $
+ * Revision 1.1  2000/07/01 11:23:52  mdw
+ * Public-key operations, for symmetry with `rsa-priv.c'.  Functions for
+ * doing padded RSA encryption and signature verification.
+ *
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <mLib/alloc.h>
+#include <mLib/bits.h>
+#include <mLib/dstr.h>
+
+#include "mp.h"
+#include "mpmont.h"
+#include "rsa.h"
+
+/*----- Public key operations ---------------------------------------------*/
+
+/* --- @rsa_pubcreate@ --- *
+ *
+ * Arguments:  @rsa_pubctx *rd@ = pointer to an RSA public key context
+ *             @rsa_pub *rp@ = pointer to RSA public key
+ *
+ * Returns:    ---
+ *
+ * Use:                Initializes an RSA public-key context.
+ */
+
+void rsa_pubcreate(rsa_pubctx *rd, rsa_pub *rp)
+{
+  rd->rp = rp;
+  mpmont_create(&rd->mm, rp->n);
+}
+
+/* --- @rsa_pubdestroy@ --- *
+ *
+ * Arguments:  @rsa_pubctx *rd@ = pointer to an RSA public key context
+ *
+ * Returns:    ---
+ *
+ * Use:                Destroys an RSA public-key context.
+ */
+
+void rsa_pubdestroy(rsa_pubctx *rd)
+{
+  mpmont_destroy(&rd->mm);
+}
+
+/* --- @rsa_pubop@ --- *
+ *
+ * Arguments:  @rsa_pubctx *rd@ = pointer to an RSA public key context
+ *             @mp *d@ = destination
+ *             @mp *p@ = input message
+ *
+ * Returns:    The transformed output message.
+ *
+ * Use:                Performs an RSA public key operation.
+ */
+
+mp *rsa_pubop(rsa_pubctx *rd, mp *d, mp *p)
+{
+  return (mpmont_exp(&rd->mm, d, p, rd->rp->e));
+}
+
+/* --- @rsa_qpubop@ --- *
+ *
+ * Arguments:  @rsa_pub *rp@ = pointer to RSA parameters
+ *             @mp *d@ = destination
+ *             @mp *p@ = input message
+ *
+ * Returns:    Correctly transformed output message.
+ *
+ * Use:                Performs an RSA public key operation.
+ */
+
+mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c)
+{
+  rsa_pubctx rd;
+  rsa_pubcreate(&rd, rp);
+  d = rsa_pubop(&rd, d, c);
+  rsa_pubdestroy(&rd);
+  return (d);
+}
+
+/*----- Operations with padding -------------------------------------------*/
+
+/* --- @rsa_encrypt@ --- *
+ *
+ * Arguments:  @rsa_pubctx *rp@ = pointer to an RSA public key context
+ *             @const void *m@ = pointer to input message
+ *             @size_t sz@ = size of input message
+ *             @dstr *d@ = pointer to output string
+ *             @rsa_encodeproc e@ = encoding procedure
+ *             @void *earg@ = argument pointer for encoding procedure
+ *
+ * Returns:    The length of the output string if successful, negative on
+ *             failure.
+ *
+ * Use:                Does RSA encryption.
+ */
+
+int rsa_encrypt(rsa_pubctx *rp, const void *m, size_t sz,
+               dstr *d, rsa_encodeproc e, void *earg)
+{
+  mp *x;
+  size_t n = mp_octets(rp->rp->n);
+  octet *p;
+  int rc;
+
+  /* --- Sort out some space --- */
+
+  dstr_ensure(d, n);
+  p = d->buf + d->len;
+  p[0] = 0;
+
+  /* --- Do the packing --- */
+
+  if ((rc = e(m, sz, p, n, earg)) < 0)
+    return (rc);
+
+  /* --- Do the encryption --- */
+
+  x = mp_loadb(MP_NEWSEC, p, n);
+  x = rsa_pubop(rp, x, x);
+  mp_storeb(x, p, n);
+  d->len += n;
+  mp_drop(x);
+  return (n);
+}
+
+/* --- @rsa_verify@ --- *
+ *
+ * Arguments:  @rsa_pubctx *rp@ = pointer to an RSA public key context
+ *             @const void *m@ = pointer to input message
+ *             @size_t sz@ = size of input message
+ *             @dstr *d@ = pointer to output string
+ *             @rsa_decodeproc e@ = decoding procedure
+ *             @void *earg@ = argument pointer for decoding procedure
+ *
+ * Returns:    The length of the output string if successful, negative on
+ *             failure.
+ *
+ * Use:                Does RSA signature verification.
+ */
+
+int rsa_verify(rsa_pubctx *rp, const void *m, size_t sz,
+              dstr *d, rsa_decodeproc e, void *earg)
+{
+  mp *x;
+  size_t n = mp_octets(rp->rp->n);
+  octet *p;
+  int rc;
+
+  /* --- Do the exponentiation --- */
+
+  p = x_alloc(d->a, n);
+  x = mp_loadb(MP_NEW, m, sz);
+  x = rsa_pubop(rp, x, x);
+  mp_storeb(x, p, n);
+  mp_drop(x);
+
+  /* --- Do the decoding --- */
+
+  rc = e(p, n, d, earg);
+  x_free(d->a, p);
+  return (rc);
+}
+
+/*----- That's all, folks -------------------------------------------------*/