fips_dsa_sign.c revision 296465 
1/* fips_dsa_sign.c */
2/*
3 * Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL project
4 * 2007.
5 */
6/* ====================================================================
7 * Copyright (c) 2007 The OpenSSL Project.  All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in
18 *    the documentation and/or other materials provided with the
19 *    distribution.
20 *
21 * 3. All advertising materials mentioning features or use of this
22 *    software must display the following acknowledgment:
23 *    "This product includes software developed by the OpenSSL Project
24 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
25 *
26 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
27 *    endorse or promote products derived from this software without
28 *    prior written permission. For written permission, please contact
29 *    licensing@OpenSSL.org.
30 *
31 * 5. Products derived from this software may not be called "OpenSSL"
32 *    nor may "OpenSSL" appear in their names without prior written
33 *    permission of the OpenSSL Project.
34 *
35 * 6. Redistributions of any form whatsoever must retain the following
36 *    acknowledgment:
37 *    "This product includes software developed by the OpenSSL Project
38 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
39 *
40 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
41 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
43 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
44 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
45 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
46 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
47 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
49 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
50 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
51 * OF THE POSSIBILITY OF SUCH DAMAGE.
52 * ====================================================================
53 *
54 * This product includes cryptographic software written by Eric Young
55 * (eay@cryptsoft.com).  This product includes software written by Tim
56 * Hudson (tjh@cryptsoft.com).
57 *
58 */
59
60#include <string.h>
61#include <openssl/evp.h>
62#include <openssl/dsa.h>
63#include <openssl/err.h>
64#include <openssl/sha.h>
65#include <openssl/bn.h>
66
67#ifdef OPENSSL_FIPS
68
69/*
70 * FIPS versions of DSA_sign() and DSA_verify(). These include a tiny ASN1
71 * encoder/decoder to handle the specific case of a DSA signature.
72 */
73
74# if 0
75int FIPS_dsa_size(DSA *r)
76{
77    int ilen;
78    ilen = BN_num_bytes(r->q);
79    if (ilen > 20)
80        return -1;
81    /* If MSB set need padding byte */
82    ilen++;
83    /*
84     * Also need 2 bytes INTEGER header for r and s plus 2 bytes SEQUENCE
85     * header making 6 in total.
86     */
87    return ilen * 2 + 6;
88}
89# endif
90
91/*
92 * Tiny ASN1 encoder for DSA_SIG structure. We can assume r, s smaller than
93 * 0x80 octets as by the DSA standards they will be less than 2^160
94 */
95
96int FIPS_dsa_sig_encode(unsigned char *out, DSA_SIG *sig)
97{
98    int rlen, slen, rpad, spad, seqlen;
99    rlen = BN_num_bytes(sig->r);
100    if (rlen > 20)
101        return -1;
102    if (BN_num_bits(sig->r) & 0x7)
103        rpad = 0;
104    else
105        rpad = 1;
106    slen = BN_num_bytes(sig->s);
107    if (slen > 20)
108        return -1;
109    if (BN_num_bits(sig->s) & 0x7)
110        spad = 0;
111    else
112        spad = 1;
113    /* Length of SEQUENCE, (1 tag + 1 len octet) * 2 + content octets */
114    seqlen = rlen + rpad + slen + spad + 4;
115    /* Actual encoded length: include SEQUENCE header */
116    if (!out)
117        return seqlen + 2;
118
119    /* Output SEQUENCE header */
120    *out++ = V_ASN1_SEQUENCE | V_ASN1_CONSTRUCTED;
121    *out++ = (unsigned char)seqlen;
122
123    /* Output r */
124    *out++ = V_ASN1_INTEGER;
125    *out++ = (unsigned char)(rlen + rpad);
126    if (rpad)
127        *out++ = 0;
128    BN_bn2bin(sig->r, out);
129    out += rlen;
130
131    /* Output s */
132    *out++ = V_ASN1_INTEGER;
133    *out++ = (unsigned char)(slen + spad);
134    if (spad)
135        *out++ = 0;
136    BN_bn2bin(sig->s, out);
137    return seqlen + 2;
138}
139
140/* Companion DSA_SIG decoder */
141
142int FIPS_dsa_sig_decode(DSA_SIG *sig, const unsigned char *in, int inlen)
143{
144    int seqlen, rlen, slen;
145    const unsigned char *rbin;
146    /* Sanity check */
147
148    /* Need SEQUENCE tag */
149    if (*in++ != (V_ASN1_SEQUENCE | V_ASN1_CONSTRUCTED))
150        return 0;
151    /* Get length octet */
152    seqlen = *in++;
153    /* Check sensible length value */
154    if (seqlen < 4 || seqlen > 0x7F)
155        return 0;
156    /* Check INTEGER tag */
157    if (*in++ != V_ASN1_INTEGER)
158        return 0;
159    rlen = *in++;
160    seqlen -= 2 + rlen;
161    /* Check sensible seqlen value */
162    if (seqlen < 2)
163        return 0;
164    rbin = in;
165    in += rlen;
166    /* Check INTEGER tag */
167    if (*in++ != V_ASN1_INTEGER)
168        return 0;
169    slen = *in++;
170    /*
171     * Remaining bytes of SEQUENCE should exactly match encoding of s
172     */
173    if (seqlen != (slen + 2))
174        return 0;
175    if (!sig->r && !(sig->r = BN_new()))
176        return 0;
177    if (!sig->s && !(sig->s = BN_new()))
178        return 0;
179    if (!BN_bin2bn(rbin, rlen, sig->r))
180        return 0;
181    if (!BN_bin2bn(in, slen, sig->s))
182        return 0;
183    return 1;
184}
185
186static int fips_dsa_sign(int type, const unsigned char *x, int y,
187                         unsigned char *sig, unsigned int *siglen,
188                         EVP_MD_SVCTX * sv)
189{
190    DSA *dsa = sv->key;
191    unsigned char dig[EVP_MAX_MD_SIZE];
192    unsigned int dlen;
193    DSA_SIG *s;
194    EVP_DigestFinal_ex(sv->mctx, dig, &dlen);
195    s = dsa->meth->dsa_do_sign(dig, dlen, dsa);
196    OPENSSL_cleanse(dig, dlen);
197    if (s == NULL) {
198        *siglen = 0;
199        return 0;
200    }
201    *siglen = FIPS_dsa_sig_encode(sig, s);
202    DSA_SIG_free(s);
203    if (*siglen < 0)
204        return 0;
205    return 1;
206}
207
208static int fips_dsa_verify(int type, const unsigned char *x, int y,
209                           const unsigned char *sigbuf, unsigned int siglen,
210                           EVP_MD_SVCTX * sv)
211{
212    DSA *dsa = sv->key;
213    DSA_SIG *s;
214    int ret = -1;
215    unsigned char dig[EVP_MAX_MD_SIZE];
216    unsigned int dlen;
217
218    s = DSA_SIG_new();
219    if (s == NULL)
220        return ret;
221    if (!FIPS_dsa_sig_decode(s, sigbuf, siglen))
222        goto err;
223    EVP_DigestFinal_ex(sv->mctx, dig, &dlen);
224    ret = dsa->meth->dsa_do_verify(dig, dlen, s, dsa);
225    OPENSSL_cleanse(dig, dlen);
226 err:
227    DSA_SIG_free(s);
228    return ret;
229}
230
231static int init(EVP_MD_CTX *ctx)
232{
233    return SHA1_Init(ctx->md_data);
234}
235
236static int update(EVP_MD_CTX *ctx, const void *data, size_t count)
237{
238    return SHA1_Update(ctx->md_data, data, count);
239}
240
241static int final(EVP_MD_CTX *ctx, unsigned char *md)
242{
243    return SHA1_Final(md, ctx->md_data);
244}
245
246static const EVP_MD dss1_md = {
247    NID_dsa,
248    NID_dsaWithSHA1,
249    SHA_DIGEST_LENGTH,
250    EVP_MD_FLAG_FIPS | EVP_MD_FLAG_SVCTX,
251    init,
252    update,
253    final,
254    NULL,
255    NULL,
256    (evp_sign_method *) fips_dsa_sign,
257    (evp_verify_method *) fips_dsa_verify,
258    {EVP_PKEY_DSA, EVP_PKEY_DSA2, EVP_PKEY_DSA3, EVP_PKEY_DSA4, 0},
259    SHA_CBLOCK,
260    sizeof(EVP_MD *) + sizeof(SHA_CTX),
261};
262
263const EVP_MD *EVP_dss1(void)
264{
265    return (&dss1_md);
266}
267#endif
268