ec_pmeth.c revision 1.1.1.8 
1/*
2 * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#include <stdio.h>
11#include "internal/cryptlib.h"
12#include <openssl/asn1t.h>
13#include <openssl/x509.h>
14#include <openssl/ec.h>
15#include "ec_lcl.h"
16#include <openssl/evp.h>
17#include "internal/evp_int.h"
18
19/* EC pkey context structure */
20
21typedef struct {
22    /* Key and paramgen group */
23    EC_GROUP *gen_group;
24    /* message digest */
25    const EVP_MD *md;
26    /* Duplicate key if custom cofactor needed */
27    EC_KEY *co_key;
28    /* Cofactor mode */
29    signed char cofactor_mode;
30    /* KDF (if any) to use for ECDH */
31    char kdf_type;
32    /* Message digest to use for key derivation */
33    const EVP_MD *kdf_md;
34    /* User key material */
35    unsigned char *kdf_ukm;
36    size_t kdf_ukmlen;
37    /* KDF output length */
38    size_t kdf_outlen;
39} EC_PKEY_CTX;
40
41static int pkey_ec_init(EVP_PKEY_CTX *ctx)
42{
43    EC_PKEY_CTX *dctx;
44
45    dctx = OPENSSL_zalloc(sizeof(*dctx));
46    if (dctx == NULL)
47        return 0;
48
49    dctx->cofactor_mode = -1;
50    dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
51    ctx->data = dctx;
52    return 1;
53}
54
55static int pkey_ec_copy(EVP_PKEY_CTX *dst, EVP_PKEY_CTX *src)
56{
57    EC_PKEY_CTX *dctx, *sctx;
58    if (!pkey_ec_init(dst))
59        return 0;
60    sctx = src->data;
61    dctx = dst->data;
62    if (sctx->gen_group) {
63        dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
64        if (!dctx->gen_group)
65            return 0;
66    }
67    dctx->md = sctx->md;
68
69    if (sctx->co_key) {
70        dctx->co_key = EC_KEY_dup(sctx->co_key);
71        if (!dctx->co_key)
72            return 0;
73    }
74    dctx->kdf_type = sctx->kdf_type;
75    dctx->kdf_md = sctx->kdf_md;
76    dctx->kdf_outlen = sctx->kdf_outlen;
77    if (sctx->kdf_ukm) {
78        dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
79        if (!dctx->kdf_ukm)
80            return 0;
81    } else
82        dctx->kdf_ukm = NULL;
83    dctx->kdf_ukmlen = sctx->kdf_ukmlen;
84    return 1;
85}
86
87static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
88{
89    EC_PKEY_CTX *dctx = ctx->data;
90    if (dctx) {
91        EC_GROUP_free(dctx->gen_group);
92        EC_KEY_free(dctx->co_key);
93        OPENSSL_free(dctx->kdf_ukm);
94        OPENSSL_free(dctx);
95    }
96}
97
98static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
99                        const unsigned char *tbs, size_t tbslen)
100{
101    int ret, type;
102    unsigned int sltmp;
103    EC_PKEY_CTX *dctx = ctx->data;
104    EC_KEY *ec = ctx->pkey->pkey.ec;
105
106    if (!sig) {
107        *siglen = ECDSA_size(ec);
108        return 1;
109    } else if (*siglen < (size_t)ECDSA_size(ec)) {
110        ECerr(EC_F_PKEY_EC_SIGN, EC_R_BUFFER_TOO_SMALL);
111        return 0;
112    }
113
114    if (dctx->md)
115        type = EVP_MD_type(dctx->md);
116    else
117        type = NID_sha1;
118
119    ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
120
121    if (ret <= 0)
122        return ret;
123    *siglen = (size_t)sltmp;
124    return 1;
125}
126
127static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
128                          const unsigned char *sig, size_t siglen,
129                          const unsigned char *tbs, size_t tbslen)
130{
131    int ret, type;
132    EC_PKEY_CTX *dctx = ctx->data;
133    EC_KEY *ec = ctx->pkey->pkey.ec;
134
135    if (dctx->md)
136        type = EVP_MD_type(dctx->md);
137    else
138        type = NID_sha1;
139
140    ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
141
142    return ret;
143}
144
145#ifndef OPENSSL_NO_EC
146static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key,
147                          size_t *keylen)
148{
149    int ret;
150    size_t outlen;
151    const EC_POINT *pubkey = NULL;
152    EC_KEY *eckey;
153    EC_PKEY_CTX *dctx = ctx->data;
154    if (!ctx->pkey || !ctx->peerkey) {
155        ECerr(EC_F_PKEY_EC_DERIVE, EC_R_KEYS_NOT_SET);
156        return 0;
157    }
158
159    eckey = dctx->co_key ? dctx->co_key : ctx->pkey->pkey.ec;
160
161    if (!key) {
162        const EC_GROUP *group;
163        group = EC_KEY_get0_group(eckey);
164        *keylen = (EC_GROUP_get_degree(group) + 7) / 8;
165        return 1;
166    }
167    pubkey = EC_KEY_get0_public_key(ctx->peerkey->pkey.ec);
168
169    /*
170     * NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
171     * an error, the result is truncated.
172     */
173
174    outlen = *keylen;
175
176    ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
177    if (ret <= 0)
178        return 0;
179    *keylen = ret;
180    return 1;
181}
182
183static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
184                              unsigned char *key, size_t *keylen)
185{
186    EC_PKEY_CTX *dctx = ctx->data;
187    unsigned char *ktmp = NULL;
188    size_t ktmplen;
189    int rv = 0;
190    if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
191        return pkey_ec_derive(ctx, key, keylen);
192    if (!key) {
193        *keylen = dctx->kdf_outlen;
194        return 1;
195    }
196    if (*keylen != dctx->kdf_outlen)
197        return 0;
198    if (!pkey_ec_derive(ctx, NULL, &ktmplen))
199        return 0;
200    ktmp = OPENSSL_malloc(ktmplen);
201    if (ktmp == NULL)
202        return 0;
203    if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
204        goto err;
205    /* Do KDF stuff */
206    if (!ECDH_KDF_X9_62(key, *keylen, ktmp, ktmplen,
207                        dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md))
208        goto err;
209    rv = 1;
210
211 err:
212    OPENSSL_clear_free(ktmp, ktmplen);
213    return rv;
214}
215#endif
216
217static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
218{
219    EC_PKEY_CTX *dctx = ctx->data;
220    EC_GROUP *group;
221    switch (type) {
222    case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
223        group = EC_GROUP_new_by_curve_name(p1);
224        if (group == NULL) {
225            ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_CURVE);
226            return 0;
227        }
228        EC_GROUP_free(dctx->gen_group);
229        dctx->gen_group = group;
230        return 1;
231
232    case EVP_PKEY_CTRL_EC_PARAM_ENC:
233        if (!dctx->gen_group) {
234            ECerr(EC_F_PKEY_EC_CTRL, EC_R_NO_PARAMETERS_SET);
235            return 0;
236        }
237        EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
238        return 1;
239
240#ifndef OPENSSL_NO_EC
241    case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
242        if (p1 == -2) {
243            if (dctx->cofactor_mode != -1)
244                return dctx->cofactor_mode;
245            else {
246                EC_KEY *ec_key = ctx->pkey->pkey.ec;
247                return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 :
248                    0;
249            }
250        } else if (p1 < -1 || p1 > 1)
251            return -2;
252        dctx->cofactor_mode = p1;
253        if (p1 != -1) {
254            EC_KEY *ec_key = ctx->pkey->pkey.ec;
255            if (!ec_key->group)
256                return -2;
257            /* If cofactor is 1 cofactor mode does nothing */
258            if (BN_is_one(ec_key->group->cofactor))
259                return 1;
260            if (!dctx->co_key) {
261                dctx->co_key = EC_KEY_dup(ec_key);
262                if (!dctx->co_key)
263                    return 0;
264            }
265            if (p1)
266                EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
267            else
268                EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
269        } else {
270            EC_KEY_free(dctx->co_key);
271            dctx->co_key = NULL;
272        }
273        return 1;
274#endif
275
276    case EVP_PKEY_CTRL_EC_KDF_TYPE:
277        if (p1 == -2)
278            return dctx->kdf_type;
279        if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_62)
280            return -2;
281        dctx->kdf_type = p1;
282        return 1;
283
284    case EVP_PKEY_CTRL_EC_KDF_MD:
285        dctx->kdf_md = p2;
286        return 1;
287
288    case EVP_PKEY_CTRL_GET_EC_KDF_MD:
289        *(const EVP_MD **)p2 = dctx->kdf_md;
290        return 1;
291
292    case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
293        if (p1 <= 0)
294            return -2;
295        dctx->kdf_outlen = (size_t)p1;
296        return 1;
297
298    case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
299        *(int *)p2 = dctx->kdf_outlen;
300        return 1;
301
302    case EVP_PKEY_CTRL_EC_KDF_UKM:
303        OPENSSL_free(dctx->kdf_ukm);
304        dctx->kdf_ukm = p2;
305        if (p2)
306            dctx->kdf_ukmlen = p1;
307        else
308            dctx->kdf_ukmlen = 0;
309        return 1;
310
311    case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
312        *(unsigned char **)p2 = dctx->kdf_ukm;
313        return dctx->kdf_ukmlen;
314
315    case EVP_PKEY_CTRL_MD:
316        if (EVP_MD_type((const EVP_MD *)p2) != NID_sha1 &&
317            EVP_MD_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
318            EVP_MD_type((const EVP_MD *)p2) != NID_sha224 &&
319            EVP_MD_type((const EVP_MD *)p2) != NID_sha256 &&
320            EVP_MD_type((const EVP_MD *)p2) != NID_sha384 &&
321            EVP_MD_type((const EVP_MD *)p2) != NID_sha512) {
322            ECerr(EC_F_PKEY_EC_CTRL, EC_R_INVALID_DIGEST_TYPE);
323            return 0;
324        }
325        dctx->md = p2;
326        return 1;
327
328    case EVP_PKEY_CTRL_GET_MD:
329        *(const EVP_MD **)p2 = dctx->md;
330        return 1;
331
332    case EVP_PKEY_CTRL_PEER_KEY:
333        /* Default behaviour is OK */
334    case EVP_PKEY_CTRL_DIGESTINIT:
335    case EVP_PKEY_CTRL_PKCS7_SIGN:
336    case EVP_PKEY_CTRL_CMS_SIGN:
337        return 1;
338
339    default:
340        return -2;
341
342    }
343}
344
345static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
346                            const char *type, const char *value)
347{
348    if (strcmp(type, "ec_paramgen_curve") == 0) {
349        int nid;
350        nid = EC_curve_nist2nid(value);
351        if (nid == NID_undef)
352            nid = OBJ_sn2nid(value);
353        if (nid == NID_undef)
354            nid = OBJ_ln2nid(value);
355        if (nid == NID_undef) {
356            ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_CURVE);
357            return 0;
358        }
359        return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
360    } else if (strcmp(type, "ec_param_enc") == 0) {
361        int param_enc;
362        if (strcmp(value, "explicit") == 0)
363            param_enc = 0;
364        else if (strcmp(value, "named_curve") == 0)
365            param_enc = OPENSSL_EC_NAMED_CURVE;
366        else
367            return -2;
368        return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
369    } else if (strcmp(type, "ecdh_kdf_md") == 0) {
370        const EVP_MD *md;
371        if ((md = EVP_get_digestbyname(value)) == NULL) {
372            ECerr(EC_F_PKEY_EC_CTRL_STR, EC_R_INVALID_DIGEST);
373            return 0;
374        }
375        return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
376    } else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
377        int co_mode;
378        co_mode = atoi(value);
379        return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
380    }
381
382    return -2;
383}
384
385static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
386{
387    EC_KEY *ec = NULL;
388    EC_PKEY_CTX *dctx = ctx->data;
389    int ret = 0;
390    if (dctx->gen_group == NULL) {
391        ECerr(EC_F_PKEY_EC_PARAMGEN, EC_R_NO_PARAMETERS_SET);
392        return 0;
393    }
394    ec = EC_KEY_new();
395    if (ec == NULL)
396        return 0;
397    ret = EC_KEY_set_group(ec, dctx->gen_group);
398    if (ret)
399        EVP_PKEY_assign_EC_KEY(pkey, ec);
400    else
401        EC_KEY_free(ec);
402    return ret;
403}
404
405static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
406{
407    EC_KEY *ec = NULL;
408    EC_PKEY_CTX *dctx = ctx->data;
409    if (ctx->pkey == NULL && dctx->gen_group == NULL) {
410        ECerr(EC_F_PKEY_EC_KEYGEN, EC_R_NO_PARAMETERS_SET);
411        return 0;
412    }
413    ec = EC_KEY_new();
414    if (!ec)
415        return 0;
416    EVP_PKEY_assign_EC_KEY(pkey, ec);
417    if (ctx->pkey) {
418        /* Note: if error return, pkey is freed by parent routine */
419        if (!EVP_PKEY_copy_parameters(pkey, ctx->pkey))
420            return 0;
421    } else {
422        if (!EC_KEY_set_group(ec, dctx->gen_group))
423            return 0;
424    }
425    return EC_KEY_generate_key(pkey->pkey.ec);
426}
427
428const EVP_PKEY_METHOD ec_pkey_meth = {
429    EVP_PKEY_EC,
430    0,
431    pkey_ec_init,
432    pkey_ec_copy,
433    pkey_ec_cleanup,
434
435    0,
436    pkey_ec_paramgen,
437
438    0,
439    pkey_ec_keygen,
440
441    0,
442    pkey_ec_sign,
443
444    0,
445    pkey_ec_verify,
446
447    0, 0,
448
449    0, 0, 0, 0,
450
451    0, 0,
452
453    0, 0,
454
455    0,
456#ifndef OPENSSL_NO_EC
457    pkey_ec_kdf_derive,
458#else
459    0,
460#endif
461    pkey_ec_ctrl,
462    pkey_ec_ctrl_str
463};
464