X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/pub/rsa-pub.c

diff --git a/pub/rsa-pub.c b/pub/rsa-pub.c
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+/* -*-c-*-
+ *
+ * [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.
+ */
+
+/*----- 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
+ *		@mp *d@ = proposed destination integer
+ *		@const void *m@ = pointer to input message
+ *		@size_t msz@ = size of input message
+ *		@rsa_pad *e@ = encoding procedure
+ *		@void *earg@ = argument pointer for encoding procedure
+ *
+ * Returns:	The encrypted message, as a multiprecision integer, or null
+ *		on failure.
+ *
+ * Use:		Does RSA encryption.
+ */
+
+mp *rsa_encrypt(rsa_pubctx *rp, mp *d, const void *m, size_t msz,
+		rsa_pad *e, void *earg)
+{
+  octet *p;
+  unsigned long nb = mp_bits(rp->rp->n);
+  size_t n = (nb + 7)/8;
+  arena *a = d && d->a ? d->a->a : arena_global;
+
+  p = x_alloc(a, n);
+  d = e(d, m, msz, p, n, nb, earg);
+  x_free(a, p);
+  return (d ? rsa_pubop(rp, d, d) : 0);
+}
+
+/* --- @rsa_verify@ --- *
+ *
+ * Arguments:	@rsa_pubctx *rp@ = pointer to an RSA public key contxt
+ *		@mp *s@ = the signature, as a multiprecision integer
+ *		@const void *m@ = pointer to message to verify, or null
+ *		@size_t msz@ = size of input message
+ *		@dstr *d@ = pointer to output string, or null
+ *		@rsa_vfrunpad *e@ = decoding procedure
+ *		@void *earg@ = argument pointer for decoding procedure
+ *
+ * Returns:	The length of the output string if successful (0 if no output
+ *		was wanted); negative on failure.
+ *
+ * Use:		Does RSA signature verification.  To use a signature scheme
+ *		with recovery, pass in @m == 0@ and @d != 0@: the recovered
+ *		message should appear in @d@.  To use a signature scheme with
+ *		appendix, provide @m != 0@ and @d == 0@; the result should be
+ *		zero for success.
+ */
+
+int rsa_verify(rsa_pubctx *rp, mp *s, const void *m, size_t msz,
+	       dstr *d, rsa_vrfunpad *e, void *earg)
+{
+  mp *p = rsa_pubop(rp, MP_NEW, s);
+  unsigned long nb = mp_bits(rp->rp->n);
+  size_t n = (nb + 7)/8;
+  dstr dd = DSTR_INIT;
+  int rc;
+
+  /* --- Decoder protocol --- *
+   *
+   * We deal with two kinds of decoders: ones with message recovery and ones
+   * with appendix.  A decoder with recovery will leave a message in the
+   * buffer and exit nonzero: we'll check that against @m@ if provided and
+   * just leave it otherwise.  A decoder with appendix will inspect @m@ and
+   * return zero or @-1@ itself.
+   */
+
+  if (!d) d = &dd;
+  dstr_ensure(d, n);
+  rc = e(p, m, msz, (octet *)d->buf + d->len, n, nb, earg);
+  if (rc > 0 && m) {
+    if (rc != msz || memcmp(d->buf + d->len, m, msz) != 0)
+      rc = -1;
+    else
+      rc = 0;
+  }
+  if (rc > 0)
+    d->len += rc;
+  mp_drop(p);
+  dstr_destroy(&dd);
+  return (rc);
+}
+
+/*----- That's all, folks -------------------------------------------------*/