X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=rsa.c;h=28a4c1b3225c3caefbb5a296f7582a149b63d245;hb=4a6ee8b677fd7addc97fc0d245f95ddde3b5f8e4;hp=f7dd69db6f69115e03c94779a2529468b642619f;hpb=f15aefe4e0bb264fc1ceac17c7bbe1a534d190c9;p=secnet.git

diff --git a/rsa.c b/rsa.c
index f7dd69d..28a4c1b 100644
--- a/rsa.c
+++ b/rsa.c
@@ -1,25 +1,56 @@
-/* This file is part of secnet, and is distributed under the terms of
-   the GNU General Public License version 2 or later.
+/*
+ * rsa.c: implementation of RSA with PKCS#1 padding
+ */
+/*
+ * This file is Free Software.  It was originally written for secnet.
+ *
+ * Copyright 1995-2003 Stephen Early
+ * Copyright 2002-2014 Ian Jackson
+ * Copyright 2001      Simon Tatham
+ * Copyright 2013      Mark Wooding
+ *
+ * You may redistribute secnet as a whole and/or modify it under the
+ * terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 3, or (at your option) any
+ * later version.
+ *
+ * You may redistribute this file and/or modify it under the terms of
+ * the GNU General Public License as published by the Free Software
+ * Foundation; either version 2, or (at your option) any later
+ * version.
+ *
+ * This software 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this software; if not, see
+ * https://www.gnu.org/licenses/gpl.html.
+ */
 
-   Copyright (C) 1995-2002 Stephen Early
-   Copyright (C) 2001 Simon Tatham
-   Copyright (C) 2002 Ian Jackson
-   */
 
 #include <stdio.h>
 #include <string.h>
 #include <gmp.h>
 #include "secnet.h"
 #include "util.h"
+#include "unaligned.h"
 
 #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
 
 #define mpp(s,n) do { char *p = mpz_get_str(NULL,16,n); printf("%s 0x%sL\n", s, p); free(p); } while (0)
 
+struct rsacommon {
+    struct hash_if *hashi;
+    uint8_t *hashbuf;
+};
+
 struct rsapriv {
     closure_t cl;
-    struct rsaprivkey_if ops;
+    struct sigprivkey_if ops;
     struct cloc loc;
+    struct rsacommon common;
     MP_INT n;
     MP_INT p, dp;
     MP_INT q, dq;
@@ -27,8 +58,9 @@ struct rsapriv {
 };
 struct rsapub {
     closure_t cl;
-    struct rsapubkey_if ops;
+    struct sigpubkey_if ops;
     struct cloc loc;
+    struct rsacommon common;
     MP_INT e;
     MP_INT n;
 };
@@ -42,6 +74,27 @@ struct rsapub {
 
 static const char *hexchars="0123456789abcdef";
 
+static void rsa_sethash(struct rsacommon *c, struct hash_if *hash)
+{
+    free(c->hashbuf);
+    c->hashbuf=safe_malloc(hash->hlen, "generate_msg");
+    c->hashi=hash;
+}
+static void rsa_pub_sethash(void *sst, struct hash_if *hash)
+{
+    struct rsapub *st=sst;
+    rsa_sethash(&st->common, hash);
+}
+static void rsa_priv_sethash(void *sst, struct hash_if *hash)
+{
+    struct rsapriv *st=sst;
+    rsa_sethash(&st->common, hash);
+}
+static void rsa_hash(struct rsacommon *c, const uint8_t *buf, int32_t len)
+{
+    hash_hash(c->hashi,buf,len,c->hashbuf);
+}
+
 static void emsa_pkcs1(MP_INT *n, MP_INT *m,
 		       const uint8_t *data, int32_t datalen)
 {
@@ -90,17 +143,20 @@ static void emsa_pkcs1(MP_INT *n, MP_INT *m,
     mpz_set_str(m, buff, 16);
 }
 
-static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
+static bool_t rsa_sign(void *sst, uint8_t *data, int32_t datalen,
+		       struct buffer_if *msg)
 {
     struct rsapriv *st=sst;
     MP_INT a, b, u, v, tmp, tmp2;
-    string_t signature;
+    string_t signature = 0;
+    bool_t ok;
 
     mpz_init(&a);
     mpz_init(&b);
 
+    rsa_hash(&st->common,data,datalen);
     /* Construct the message representative. */
-    emsa_pkcs1(&st->n, &a, data, datalen);
+    emsa_pkcs1(&st->n, &a, st->common.hashbuf, st->common.hashi->hlen);
 
     /*
      * Produce an RSA signature (a^d mod n) using the Chinese
@@ -124,8 +180,8 @@ static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
     mpz_init(&u);
     mpz_init(&v);
 
-    mpz_powm(&u, &a, &st->dp, &st->p);
-    mpz_powm(&v, &a, &st->dq, &st->q);
+    mpz_powm_sec(&u, &a, &st->dp, &st->p);
+    mpz_powm_sec(&v, &a, &st->dq, &st->q);
     mpz_sub(&tmp, &u, &v);
     mpz_mul(&tmp2, &tmp, &st->w);
     mpz_add(&tmp, &tmp2, &v);
@@ -138,14 +194,45 @@ static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
 
     signature=write_mpstring(&b);
 
+    uint8_t *op = buf_append(msg,2);
+    if (!op) { ok=False; goto out; }
+    size_t l = strlen(signature);
+    assert(l < 65536);
+    put_uint16(op, l);
+    op = buf_append(msg,l);
+    if (!op) { ok=False; goto out; }
+    memcpy(op, signature, l);
+
+    ok = True;
+
+ out:
+    free(signature);
     mpz_clear(&b);
     mpz_clear(&a);
-    return signature;
+    return ok;
 }
 
-static rsa_checksig_fn rsa_sig_check;
+static bool_t rsa_sig_unpick(void *sst, struct buffer_if *msg,
+			     struct alg_msg_data *sig)
+{
+    uint8_t *lp = buf_unprepend(msg, 2);
+    if (!lp) return False;
+    sig->len = get_uint16(lp);
+    sig->start = buf_unprepend(msg, sig->len);
+    if (!sig->start) return False;
+
+    /* In `rsa_sig_check' below, we assume that we can write a nul
+     * terminator following the signature.  Make sure there's enough space.
+     */
+    if (msg->start >= msg->base + msg->alloclen)
+	return False;
+
+    return True;
+}
+
+static sig_checksig_fn rsa_sig_check;
 static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
-			    cstring_t signature)
+			    const struct alg_msg_data *sig)
 {
     struct rsapub *st=sst;
     MP_INT a, b, c;
@@ -155,9 +242,14 @@ static bool_t rsa_sig_check(void *sst, uint8_t *data, int32_t datalen,
     mpz_init(&b);
     mpz_init(&c);
 
-    emsa_pkcs1(&st->n, &a, data, datalen);
+    rsa_hash(&st->common,data,datalen);
+    emsa_pkcs1(&st->n, &a, st->common.hashbuf, st->common.hashi->hlen);
 
-    mpz_set_str(&b, signature, 16);
+    /* Terminate signature with a '0' - already checked that this will fit */
+    int save = sig->start[sig->len];
+    sig->start[sig->len] = 0;
+    mpz_set_str(&b, sig->start, 16);
+    sig->start[sig->len] = save;
 
     mpz_powm(&c, &b, &st->e, &st->n);
 
@@ -177,12 +269,15 @@ static list_t *rsapub_apply(closure_t *self, struct cloc loc, dict_t *context,
     item_t *i;
     string_t e,n;
 
-    st=safe_malloc(sizeof(*st),"rsapub_apply");
+    NEW(st);
     st->cl.description="rsapub";
-    st->cl.type=CL_RSAPUBKEY;
+    st->cl.type=CL_SIGPUBKEY;
     st->cl.apply=NULL;
     st->cl.interface=&st->ops;
     st->ops.st=st;
+    st->ops.sethash=rsa_pub_sethash;
+    st->common.hashbuf=NULL;
+    st->ops.unpick=rsa_sig_unpick;
     st->ops.check=rsa_sig_check;
     st->loc=loc;
 
@@ -255,12 +350,14 @@ static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
     MP_INT e,d,iqmp,tmp,tmp2,tmp3;
     bool_t valid;
 
-    st=safe_malloc(sizeof(*st),"rsapriv_apply");
+    NEW(st);
     st->cl.description="rsapriv";
-    st->cl.type=CL_RSAPRIVKEY;
+    st->cl.type=CL_SIGPRIVKEY;
     st->cl.apply=NULL;
     st->cl.interface=&st->ops;
     st->ops.st=st;
+    st->ops.sethash=rsa_priv_sethash;
+    st->common.hashbuf=NULL;
     st->ops.sign=rsa_sign;
     st->loc=loc;
 
@@ -268,7 +365,7 @@ static list_t *rsapriv_apply(closure_t *self, struct cloc loc, dict_t *context,
     i=list_elem(args,0);
     if (i) {
 	if (i->type!=t_string) {
-	    cfgfatal(i->loc,"rsa-public","first argument must be a string\n");
+	    cfgfatal(i->loc,"rsa-private","first argument must be a string\n");
 	}
 	filename=i->data.string;
     } else {