-/* 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"
struct rsapriv {
closure_t cl;
- struct rsaprivkey_if ops;
+ struct sigprivkey_if ops;
struct cloc loc;
MP_INT n;
MP_INT p, dp;
};
struct rsapub {
closure_t cl;
- struct rsapubkey_if ops;
+ struct sigpubkey_if ops;
struct cloc loc;
MP_INT e;
MP_INT n;
};
/* Sign data. NB data must be smaller than modulus */
+#define RSA_MAX_MODBYTES 2048
+/* The largest modulus I've seen is 15360 bits, which works out at 1920
+ * bytes. Using keys this big is quite implausible, but it doesn't cost us
+ * much to support them.
+ */
+
static const char *hexchars="0123456789abcdef";
-static string_t rsa_sign(void *sst, uint8_t *data, int32_t datalen)
+static void emsa_pkcs1(MP_INT *n, MP_INT *m,
+ const uint8_t *data, int32_t datalen)
{
- struct rsapriv *st=sst;
- MP_INT a, b, u, v, tmp, tmp2;
- char buff[2048];
+ char buff[2*RSA_MAX_MODBYTES + 1];
int msize, i;
- string_t signature;
-
- mpz_init(&a);
- mpz_init(&b);
/* RSA PKCS#1 v1.5 signature padding:
*
* -iwj 17.9.2002
*/
- msize=mpz_sizeinbase(&st->n, 16);
+ msize=mpz_sizeinbase(n, 16);
if (datalen*2+6>=msize) {
fatal("rsa_sign: message too big");
buff[msize]=0;
- mpz_set_str(&a, buff, 16);
+ mpz_set_str(m, buff, 16);
+}
+
+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 = 0;
+ bool_t ok;
+
+ mpz_init(&a);
+ mpz_init(&b);
+
+ /* Construct the message representative. */
+ emsa_pkcs1(&st->n, &a, data, datalen);
/*
* Produce an RSA signature (a^d mod n) using the Chinese
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);
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->siglen = get_uint16(lp);
+ sig->sigstart = buf_unprepend(msg, sig->siglen);
+ if (!sig->sigstart) 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;
- char buff[2048];
- int msize, i;
bool_t ok;
mpz_init(&a);
mpz_init(&b);
mpz_init(&c);
- msize=mpz_sizeinbase(&st->n, 16);
+ emsa_pkcs1(&st->n, &a, data, datalen);
- strcpy(buff,"0001");
-
- for (i=0; i<datalen; i++) {
- buff[msize+(-datalen+i)*2]=hexchars[(data[i]&0xf0)>>4];
- buff[msize+(-datalen+i)*2+1]=hexchars[data[i]&0xf];
- }
-
- buff[msize-datalen*2-2]= '0';
- buff[msize-datalen*2-1]= '0';
-
- for (i=4; i<msize-datalen*2-2; i++)
- buff[i]='f';
-
- buff[msize]=0;
-
- mpz_set_str(&a, buff, 16);
-
- mpz_set_str(&b, signature, 16);
+ /* Terminate signature with a '0' - already checked that this will fit */
+ int save = sig->sigstart[sig->siglen];
+ sig->sigstart[sig->siglen] = 0;
+ mpz_set_str(&b, sig->sigstart, 16);
+ sig->sigstart[sig->siglen] = save;
mpz_powm(&c, &b, &st->e, &st->n);
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.unpick=rsa_sig_unpick;
st->ops.check=rsa_sig_check;
st->loc=loc;
} else {
cfgfatal(loc,"rsa-public","you must provide an encryption key\n");
}
+ if (mpz_sizeinbase(&st->e, 256) > RSA_MAX_MODBYTES) {
+ cfgfatal(loc, "rsa-public", "implausibly large public exponent\n");
+ }
i=list_elem(args,1);
if (i) {
} else {
cfgfatal(loc,"rsa-public","you must provide a modulus\n");
}
+ if (mpz_sizeinbase(&st->n, 256) > RSA_MAX_MODBYTES) {
+ cfgfatal(loc, "rsa-public", "implausibly large modulus\n");
+ }
return new_closure(&st->cl);
}
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;
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 {
/* Read the public key */
keyfile_get_int(loc,f); /* Not sure what this is */
length=(keyfile_get_short(loc,f)+7)/8;
- if (length>1024) {
+ if (length>RSA_MAX_MODBYTES) {
cfgfatal(loc,"rsa-private","implausible length %ld for modulus\n",
length);
}
read_mpbin(&st->n,b,length);
free(b);
length=(keyfile_get_short(loc,f)+7)/8;
- if (length>1024) {
+ if (length>RSA_MAX_MODBYTES) {
cfgfatal(loc,"rsa-private","implausible length %ld for e\n",length);
}
b=safe_malloc(length,"rsapriv_apply");
/* Read d */
length=(keyfile_get_short(loc,f)+7)/8;
- if (length>1024) {
+ if (length>RSA_MAX_MODBYTES) {
cfgfatal(loc,"rsa-private","implausibly long (%ld) decryption key\n",
length);
}
free(b);
/* Read iqmp (inverse of q mod p) */
length=(keyfile_get_short(loc,f)+7)/8;
- if (length>1024) {
+ if (length>RSA_MAX_MODBYTES) {
cfgfatal(loc,"rsa-private","implausibly long (%ld)"
" iqmp auxiliary value\n", length);
}
free(b);
/* Read q (the smaller of the two primes) */
length=(keyfile_get_short(loc,f)+7)/8;
- if (length>1024) {
+ if (length>RSA_MAX_MODBYTES) {
cfgfatal(loc,"rsa-private","implausibly long (%ld) q value\n",
length);
}
free(b);
/* Read p (the larger of the two primes) */
length=(keyfile_get_short(loc,f)+7)/8;
- if (length>1024) {
+ if (length>RSA_MAX_MODBYTES) {
cfgfatal(loc,"rsa-private","implausibly long (%ld) p value\n",
length);
}
/*
* Verify that d*e is congruent to 1 mod (p-1), and mod
* (q-1). This is equivalent to it being congruent to 1 mod
- * lcm(p-1,q-1), i.e. congruent to 1 mod phi(n). Note that
- * phi(n) is _not_ simply (p-1)*(q-1).
+ * lambda(n) = lcm(p-1,q-1). The usual `textbook' condition,
+ * that d e == 1 (mod (p-1)(q-1)) is sufficient, but not
+ * actually necessary.
*/
mpz_mul(&tmp, &d, &e);
mpz_sub_ui(&tmp2, &st->p, 1);
~ian / secnet.git / blobdiff