X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/898a4e2555438ff8adb08b4d82690d08715e1048..b817bfc642225b8c3c0b6a7e42d1fb949b61a606:/rsa-pub.c

diff --git a/rsa-pub.c b/rsa-pub.c
index e5ec16c..df3fed1 100644
--- a/rsa-pub.c
+++ b/rsa-pub.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: rsa-pub.c,v 1.2 2000/10/08 16:00:32 mdw Exp $
+ * $Id: rsa-pub.c,v 1.3 2004/04/08 01:36:15 mdw Exp $
  *
  * [RSA encryption with padding *
  * (c) 2000 Straylight/Edgeware
@@ -26,18 +26,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: rsa-pub.c,v $
- * Revision 1.2  2000/10/08 16:00:32  mdw
- * Fix compiler warning.
- *
- * 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>
@@ -121,82 +109,83 @@ mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c)
 /* --- @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 sz@ = size of input message
- *		@dstr *d@ = pointer to output string
- *		@rsa_encodeproc e@ = encoding procedure
+ *		@size_t msz@ = size of input message
+ *		@rsa_pad *e@ = encoding procedure
  *		@void *earg@ = argument pointer for encoding procedure
  *
- * Returns:	The length of the output string if successful, negative on
- *		failure.
+ * Returns:	The encrypted message, as a multiprecision integer, or null
+ *		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 *rsa_encrypt(rsa_pubctx *rp, mp *d, const void *m, size_t msz,
+		rsa_pad *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 = (octet *)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);
+  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 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
+ * 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, negative on
- *		failure.
+ * Returns:	The length of the output string if successful (0 if no output
+ *		was wanted); negative on failure.
  *
- * Use:		Does RSA signature verification.
+ * 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, const void *m, size_t sz,
-	       dstr *d, rsa_decodeproc e, void *earg)
+int rsa_verify(rsa_pubctx *rp, mp *s, const void *m, size_t msz,
+	       dstr *d, rsa_vrfunpad *e, void *earg)
 {
-  mp *x;
-  size_t n = mp_octets(rp->rp->n);
-  octet *p;
+  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;
 
-  /* --- 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);
+  /* --- 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.
+   */
 
-  /* --- Do the decoding --- */
-
-  rc = e(p, n, d, earg);
-  x_free(d->a, p);
+  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);
 }