1/*
2 * Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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 <assert.h>
11#include <stdlib.h>
12#include <string.h>
13#include <openssl/sha.h>
14#include <openssl/crypto.h>
15#include <openssl/err.h>
16#include <openssl/rand.h>
17#include <openssl/core_dispatch.h>
18#include <openssl/proverr.h>
19#include "internal/thread_once.h"
20#include "prov/providercommon.h"
21#include "prov/provider_ctx.h"
22#include "prov/provider_util.h"
23#include "prov/implementations.h"
24#include "drbg_local.h"
25
26static OSSL_FUNC_rand_newctx_fn drbg_hash_new_wrapper;
27static OSSL_FUNC_rand_freectx_fn drbg_hash_free;
28static OSSL_FUNC_rand_instantiate_fn drbg_hash_instantiate_wrapper;
29static OSSL_FUNC_rand_uninstantiate_fn drbg_hash_uninstantiate_wrapper;
30static OSSL_FUNC_rand_generate_fn drbg_hash_generate_wrapper;
31static OSSL_FUNC_rand_reseed_fn drbg_hash_reseed_wrapper;
32static OSSL_FUNC_rand_settable_ctx_params_fn drbg_hash_settable_ctx_params;
33static OSSL_FUNC_rand_set_ctx_params_fn drbg_hash_set_ctx_params;
34static OSSL_FUNC_rand_gettable_ctx_params_fn drbg_hash_gettable_ctx_params;
35static OSSL_FUNC_rand_get_ctx_params_fn drbg_hash_get_ctx_params;
36static OSSL_FUNC_rand_verify_zeroization_fn drbg_hash_verify_zeroization;
37
38/* 888 bits from SP800-90Ar1 10.1 table 2 */
39#define HASH_PRNG_MAX_SEEDLEN    (888/8)
40
41/* 440 bits from SP800-90Ar1 10.1 table 2 */
42#define HASH_PRNG_SMALL_SEEDLEN   (440/8)
43
44/* Determine what seedlen to use based on the block length */
45#define MAX_BLOCKLEN_USING_SMALL_SEEDLEN (256/8)
46#define INBYTE_IGNORE ((unsigned char)0xFF)
47
48typedef struct rand_drbg_hash_st {
49    PROV_DIGEST digest;
50    EVP_MD_CTX *ctx;
51    size_t blocklen;
52    unsigned char V[HASH_PRNG_MAX_SEEDLEN];
53    unsigned char C[HASH_PRNG_MAX_SEEDLEN];
54    /* Temporary value storage: should always exceed max digest length */
55    unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
56} PROV_DRBG_HASH;
57
58/*
59 * SP800-90Ar1 10.3.1 Derivation function using a Hash Function (Hash_df).
60 * The input string used is composed of:
61 *    inbyte - An optional leading byte (ignore if equal to INBYTE_IGNORE)
62 *    in - input string 1 (A Non NULL value).
63 *    in2 - optional input string (Can be NULL).
64 *    in3 - optional input string (Can be NULL).
65 *    These are concatenated as part of the DigestUpdate process.
66 */
67static int hash_df(PROV_DRBG *drbg, unsigned char *out,
68                   const unsigned char inbyte,
69                   const unsigned char *in, size_t inlen,
70                   const unsigned char *in2, size_t in2len,
71                   const unsigned char *in3, size_t in3len)
72{
73    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
74    EVP_MD_CTX *ctx = hash->ctx;
75    unsigned char *vtmp = hash->vtmp;
76    /* tmp = counter || num_bits_returned || [inbyte] */
77    unsigned char tmp[1 + 4 + 1];
78    int tmp_sz = 0;
79    size_t outlen = drbg->seedlen;
80    size_t num_bits_returned = outlen * 8;
81    /*
82     * No need to check outlen size here, as the standard only ever needs
83     * seedlen bytes which is always less than the maximum permitted.
84     */
85
86    /* (Step 3) counter = 1 (tmp[0] is the 8 bit counter) */
87    tmp[tmp_sz++] = 1;
88    /* tmp[1..4] is the fixed 32 bit no_of_bits_to_return */
89    tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 24) & 0xff);
90    tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 16) & 0xff);
91    tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 8) & 0xff);
92    tmp[tmp_sz++] = (unsigned char)(num_bits_returned & 0xff);
93    /* Tack the additional input byte onto the end of tmp if it exists */
94    if (inbyte != INBYTE_IGNORE)
95        tmp[tmp_sz++] = inbyte;
96
97    /* (Step 4) */
98    for (;;) {
99        /*
100         * (Step 4.1) out = out || Hash(tmp || in || [in2] || [in3])
101         *            (where tmp = counter || num_bits_returned || [inbyte])
102         */
103        if (!(EVP_DigestInit_ex(ctx, ossl_prov_digest_md(&hash->digest), NULL)
104                && EVP_DigestUpdate(ctx, tmp, tmp_sz)
105                && EVP_DigestUpdate(ctx, in, inlen)
106                && (in2 == NULL || EVP_DigestUpdate(ctx, in2, in2len))
107                && (in3 == NULL || EVP_DigestUpdate(ctx, in3, in3len))))
108            return 0;
109
110        if (outlen < hash->blocklen) {
111            if (!EVP_DigestFinal(ctx, vtmp, NULL))
112                return 0;
113            memcpy(out, vtmp, outlen);
114            OPENSSL_cleanse(vtmp, hash->blocklen);
115            break;
116        } else if(!EVP_DigestFinal(ctx, out, NULL)) {
117            return 0;
118        }
119
120        outlen -= hash->blocklen;
121        if (outlen == 0)
122            break;
123        /* (Step 4.2) counter++ */
124        tmp[0]++;
125        out += hash->blocklen;
126    }
127    return 1;
128}
129
130/* Helper function that just passes 2 input parameters to hash_df() */
131static int hash_df1(PROV_DRBG *drbg, unsigned char *out,
132                    const unsigned char in_byte,
133                    const unsigned char *in1, size_t in1len)
134{
135    return hash_df(drbg, out, in_byte, in1, in1len, NULL, 0, NULL, 0);
136}
137
138/*
139 * Add 2 byte buffers together. The first elements in each buffer are the top
140 * most bytes. The result is stored in the dst buffer.
141 * The final carry is ignored i.e: dst =  (dst + in) mod (2^seedlen_bits).
142 * where dst size is drbg->seedlen, and inlen <= drbg->seedlen.
143 */
144static int add_bytes(PROV_DRBG *drbg, unsigned char *dst,
145                     unsigned char *in, size_t inlen)
146{
147    size_t i;
148    int result;
149    const unsigned char *add;
150    unsigned char carry = 0, *d;
151
152    assert(drbg->seedlen >= 1 && inlen >= 1 && inlen <= drbg->seedlen);
153
154    d = &dst[drbg->seedlen - 1];
155    add = &in[inlen - 1];
156
157    for (i = inlen; i > 0; i--, d--, add--) {
158        result = *d + *add + carry;
159        carry = (unsigned char)(result >> 8);
160        *d = (unsigned char)(result & 0xff);
161    }
162
163    if (carry != 0) {
164        /* Add the carry to the top of the dst if inlen is not the same size */
165        for (i = drbg->seedlen - inlen; i > 0; --i, d--) {
166            *d += 1;     /* Carry can only be 1 */
167            if (*d != 0) /* exit if carry doesnt propagate to the next byte */
168                break;
169        }
170    }
171    return 1;
172}
173
174/* V = (V + Hash(inbyte || V  || [additional_input]) mod (2^seedlen) */
175static int add_hash_to_v(PROV_DRBG *drbg, unsigned char inbyte,
176                         const unsigned char *adin, size_t adinlen)
177{
178    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
179    EVP_MD_CTX *ctx = hash->ctx;
180
181    return EVP_DigestInit_ex(ctx, ossl_prov_digest_md(&hash->digest), NULL)
182           && EVP_DigestUpdate(ctx, &inbyte, 1)
183           && EVP_DigestUpdate(ctx, hash->V, drbg->seedlen)
184           && (adin == NULL || EVP_DigestUpdate(ctx, adin, adinlen))
185           && EVP_DigestFinal(ctx, hash->vtmp, NULL)
186           && add_bytes(drbg, hash->V, hash->vtmp, hash->blocklen);
187}
188
189/*
190 * The Hashgen() as listed in SP800-90Ar1 10.1.1.4 Hash_DRBG_Generate_Process.
191 *
192 * drbg contains the current value of V.
193 * outlen is the requested number of bytes.
194 * out is a buffer to return the generated bits.
195 *
196 * The algorithm to generate the bits is:
197 *     data = V
198 *     w = NULL
199 *     for (i = 1 to m) {
200 *        W = W || Hash(data)
201 *        data = (data + 1) mod (2^seedlen)
202 *     }
203 *     out = Leftmost(W, outlen)
204 *
205 * Returns zero if an error occurs otherwise it returns 1.
206 */
207static int hash_gen(PROV_DRBG *drbg, unsigned char *out, size_t outlen)
208{
209    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
210    unsigned char one = 1;
211
212    if (outlen == 0)
213        return 1;
214    memcpy(hash->vtmp, hash->V, drbg->seedlen);
215    for(;;) {
216        if (!EVP_DigestInit_ex(hash->ctx, ossl_prov_digest_md(&hash->digest),
217                               NULL)
218                || !EVP_DigestUpdate(hash->ctx, hash->vtmp, drbg->seedlen))
219            return 0;
220
221        if (outlen < hash->blocklen) {
222            if (!EVP_DigestFinal(hash->ctx, hash->vtmp, NULL))
223                return 0;
224            memcpy(out, hash->vtmp, outlen);
225            return 1;
226        } else {
227            if (!EVP_DigestFinal(hash->ctx, out, NULL))
228                return 0;
229            outlen -= hash->blocklen;
230            if (outlen == 0)
231                break;
232            out += hash->blocklen;
233        }
234        add_bytes(drbg, hash->vtmp, &one, 1);
235    }
236    return 1;
237}
238
239/*
240 * SP800-90Ar1 10.1.1.2 Hash_DRBG_Instantiate_Process:
241 *
242 * ent is entropy input obtained from a randomness source of length ent_len.
243 * nonce is a string of bytes of length nonce_len.
244 * pstr is a personalization string received from an application. May be NULL.
245 *
246 * Returns zero if an error occurs otherwise it returns 1.
247 */
248static int drbg_hash_instantiate(PROV_DRBG *drbg,
249                                 const unsigned char *ent, size_t ent_len,
250                                 const unsigned char *nonce, size_t nonce_len,
251                                 const unsigned char *pstr, size_t pstr_len)
252{
253    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
254
255    EVP_MD_CTX_free(hash->ctx);
256    hash->ctx = EVP_MD_CTX_new();
257
258    /* (Step 1-3) V = Hash_df(entropy||nonce||pers, seedlen) */
259    return hash->ctx != NULL
260           && hash_df(drbg, hash->V, INBYTE_IGNORE,
261                      ent, ent_len, nonce, nonce_len, pstr, pstr_len)
262           /* (Step 4) C = Hash_df(0x00||V, seedlen) */
263           && hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen);
264}
265
266static int drbg_hash_instantiate_wrapper(void *vdrbg, unsigned int strength,
267                                         int prediction_resistance,
268                                         const unsigned char *pstr,
269                                         size_t pstr_len,
270                                         const OSSL_PARAM params[])
271{
272    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
273
274    if (!ossl_prov_is_running() || !drbg_hash_set_ctx_params(drbg, params))
275        return 0;
276    return ossl_prov_drbg_instantiate(drbg, strength, prediction_resistance,
277                                      pstr, pstr_len);
278}
279
280/*
281 * SP800-90Ar1 10.1.1.3 Hash_DRBG_Reseed_Process:
282 *
283 * ent is entropy input bytes obtained from a randomness source.
284 * addin is additional input received from an application. May be NULL.
285 *
286 * Returns zero if an error occurs otherwise it returns 1.
287 */
288static int drbg_hash_reseed(PROV_DRBG *drbg,
289                            const unsigned char *ent, size_t ent_len,
290                            const unsigned char *adin, size_t adin_len)
291{
292    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
293
294    /* (Step 1-2) V = Hash_df(0x01 || V || entropy_input || additional_input) */
295    /* V about to be updated so use C as output instead */
296    if (!hash_df(drbg, hash->C, 0x01, hash->V, drbg->seedlen, ent, ent_len,
297                 adin, adin_len))
298        return 0;
299    memcpy(hash->V, hash->C, drbg->seedlen);
300    /* (Step 4) C = Hash_df(0x00||V, seedlen) */
301    return hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen);
302}
303
304static int drbg_hash_reseed_wrapper(void *vdrbg, int prediction_resistance,
305                                    const unsigned char *ent, size_t ent_len,
306                                    const unsigned char *adin, size_t adin_len)
307{
308    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
309
310    return ossl_prov_drbg_reseed(drbg, prediction_resistance, ent, ent_len,
311                                 adin, adin_len);
312}
313
314/*
315 * SP800-90Ar1 10.1.1.4 Hash_DRBG_Generate_Process:
316 *
317 * Generates pseudo random bytes using the drbg.
318 * out is a buffer to fill with outlen bytes of pseudo random data.
319 * addin is additional input received from an application. May be NULL.
320 *
321 * Returns zero if an error occurs otherwise it returns 1.
322 */
323static int drbg_hash_generate(PROV_DRBG *drbg,
324                              unsigned char *out, size_t outlen,
325                              const unsigned char *adin, size_t adin_len)
326{
327    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
328    unsigned char counter[4];
329    int reseed_counter = drbg->generate_counter;
330
331    counter[0] = (unsigned char)((reseed_counter >> 24) & 0xff);
332    counter[1] = (unsigned char)((reseed_counter >> 16) & 0xff);
333    counter[2] = (unsigned char)((reseed_counter >> 8) & 0xff);
334    counter[3] = (unsigned char)(reseed_counter & 0xff);
335
336    return hash->ctx != NULL
337           && (adin == NULL
338           /* (Step 2) if adin != NULL then V = V + Hash(0x02||V||adin) */
339               || adin_len == 0
340               || add_hash_to_v(drbg, 0x02, adin, adin_len))
341           /* (Step 3) Hashgen(outlen, V) */
342           && hash_gen(drbg, out, outlen)
343           /* (Step 4/5) H = V = (V + Hash(0x03||V) mod (2^seedlen_bits) */
344           && add_hash_to_v(drbg, 0x03, NULL, 0)
345           /* (Step 5) V = (V + H + C + reseed_counter) mod (2^seedlen_bits) */
346           /* V = (V + C) mod (2^seedlen_bits) */
347           && add_bytes(drbg, hash->V, hash->C, drbg->seedlen)
348           /* V = (V + reseed_counter) mod (2^seedlen_bits) */
349           && add_bytes(drbg, hash->V, counter, 4);
350}
351
352static int drbg_hash_generate_wrapper
353    (void *vdrbg, unsigned char *out, size_t outlen, unsigned int strength,
354     int prediction_resistance, const unsigned char *adin, size_t adin_len)
355{
356    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
357
358    return ossl_prov_drbg_generate(drbg, out, outlen, strength,
359                                   prediction_resistance, adin, adin_len);
360}
361
362static int drbg_hash_uninstantiate(PROV_DRBG *drbg)
363{
364    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
365
366    OPENSSL_cleanse(hash->V, sizeof(hash->V));
367    OPENSSL_cleanse(hash->C, sizeof(hash->C));
368    OPENSSL_cleanse(hash->vtmp, sizeof(hash->vtmp));
369    return ossl_prov_drbg_uninstantiate(drbg);
370}
371
372static int drbg_hash_uninstantiate_wrapper(void *vdrbg)
373{
374    return drbg_hash_uninstantiate((PROV_DRBG *)vdrbg);
375}
376
377static int drbg_hash_verify_zeroization(void *vdrbg)
378{
379    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
380    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
381
382    PROV_DRBG_VERYIFY_ZEROIZATION(hash->V);
383    PROV_DRBG_VERYIFY_ZEROIZATION(hash->C);
384    PROV_DRBG_VERYIFY_ZEROIZATION(hash->vtmp);
385    return 1;
386}
387
388static int drbg_hash_new(PROV_DRBG *ctx)
389{
390    PROV_DRBG_HASH *hash;
391
392    hash = OPENSSL_secure_zalloc(sizeof(*hash));
393    if (hash == NULL) {
394        ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
395        return 0;
396    }
397
398    ctx->data = hash;
399    ctx->seedlen = HASH_PRNG_MAX_SEEDLEN;
400    ctx->max_entropylen = DRBG_MAX_LENGTH;
401    ctx->max_noncelen = DRBG_MAX_LENGTH;
402    ctx->max_perslen = DRBG_MAX_LENGTH;
403    ctx->max_adinlen = DRBG_MAX_LENGTH;
404
405    /* Maximum number of bits per request = 2^19  = 2^16 bytes */
406    ctx->max_request = 1 << 16;
407    return 1;
408}
409
410static void *drbg_hash_new_wrapper(void *provctx, void *parent,
411                                   const OSSL_DISPATCH *parent_dispatch)
412{
413    return ossl_rand_drbg_new(provctx, parent, parent_dispatch, &drbg_hash_new,
414                              &drbg_hash_instantiate, &drbg_hash_uninstantiate,
415                              &drbg_hash_reseed, &drbg_hash_generate);
416}
417
418static void drbg_hash_free(void *vdrbg)
419{
420    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
421    PROV_DRBG_HASH *hash;
422
423    if (drbg != NULL && (hash = (PROV_DRBG_HASH *)drbg->data) != NULL) {
424        EVP_MD_CTX_free(hash->ctx);
425        ossl_prov_digest_reset(&hash->digest);
426        OPENSSL_secure_clear_free(hash, sizeof(*hash));
427    }
428    ossl_rand_drbg_free(drbg);
429}
430
431static int drbg_hash_get_ctx_params(void *vdrbg, OSSL_PARAM params[])
432{
433    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
434    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
435    const EVP_MD *md;
436    OSSL_PARAM *p;
437
438    p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_DIGEST);
439    if (p != NULL) {
440        md = ossl_prov_digest_md(&hash->digest);
441        if (md == NULL || !OSSL_PARAM_set_utf8_string(p, EVP_MD_get0_name(md)))
442            return 0;
443    }
444
445    return ossl_drbg_get_ctx_params(drbg, params);
446}
447
448static const OSSL_PARAM *drbg_hash_gettable_ctx_params(ossl_unused void *vctx,
449                                                       ossl_unused void *p_ctx)
450{
451    static const OSSL_PARAM known_gettable_ctx_params[] = {
452        OSSL_PARAM_utf8_string(OSSL_DRBG_PARAM_DIGEST, NULL, 0),
453        OSSL_PARAM_DRBG_GETTABLE_CTX_COMMON,
454        OSSL_PARAM_END
455    };
456    return known_gettable_ctx_params;
457}
458
459static int drbg_hash_set_ctx_params(void *vctx, const OSSL_PARAM params[])
460{
461    PROV_DRBG *ctx = (PROV_DRBG *)vctx;
462    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)ctx->data;
463    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
464    const EVP_MD *md;
465
466    if (!ossl_prov_digest_load_from_params(&hash->digest, params, libctx))
467        return 0;
468
469    md = ossl_prov_digest_md(&hash->digest);
470    if (md != NULL) {
471        if ((EVP_MD_get_flags(md) & EVP_MD_FLAG_XOF) != 0) {
472            ERR_raise(ERR_LIB_PROV, PROV_R_XOF_DIGESTS_NOT_ALLOWED);
473            return 0;
474        }
475
476        /* These are taken from SP 800-90 10.1 Table 2 */
477        hash->blocklen = EVP_MD_get_size(md);
478        /* See SP800-57 Part1 Rev4 5.6.1 Table 3 */
479        ctx->strength = 64 * (hash->blocklen >> 3);
480        if (ctx->strength > 256)
481            ctx->strength = 256;
482        if (hash->blocklen > MAX_BLOCKLEN_USING_SMALL_SEEDLEN)
483            ctx->seedlen = HASH_PRNG_MAX_SEEDLEN;
484        else
485            ctx->seedlen = HASH_PRNG_SMALL_SEEDLEN;
486
487        ctx->min_entropylen = ctx->strength / 8;
488        ctx->min_noncelen = ctx->min_entropylen / 2;
489    }
490
491    return ossl_drbg_set_ctx_params(ctx, params);
492}
493
494static const OSSL_PARAM *drbg_hash_settable_ctx_params(ossl_unused void *vctx,
495                                                       ossl_unused void *p_ctx)
496{
497    static const OSSL_PARAM known_settable_ctx_params[] = {
498        OSSL_PARAM_utf8_string(OSSL_DRBG_PARAM_PROPERTIES, NULL, 0),
499        OSSL_PARAM_utf8_string(OSSL_DRBG_PARAM_DIGEST, NULL, 0),
500        OSSL_PARAM_DRBG_SETTABLE_CTX_COMMON,
501        OSSL_PARAM_END
502    };
503    return known_settable_ctx_params;
504}
505
506const OSSL_DISPATCH ossl_drbg_hash_functions[] = {
507    { OSSL_FUNC_RAND_NEWCTX, (void(*)(void))drbg_hash_new_wrapper },
508    { OSSL_FUNC_RAND_FREECTX, (void(*)(void))drbg_hash_free },
509    { OSSL_FUNC_RAND_INSTANTIATE,
510      (void(*)(void))drbg_hash_instantiate_wrapper },
511    { OSSL_FUNC_RAND_UNINSTANTIATE,
512      (void(*)(void))drbg_hash_uninstantiate_wrapper },
513    { OSSL_FUNC_RAND_GENERATE, (void(*)(void))drbg_hash_generate_wrapper },
514    { OSSL_FUNC_RAND_RESEED, (void(*)(void))drbg_hash_reseed_wrapper },
515    { OSSL_FUNC_RAND_ENABLE_LOCKING, (void(*)(void))ossl_drbg_enable_locking },
516    { OSSL_FUNC_RAND_LOCK, (void(*)(void))ossl_drbg_lock },
517    { OSSL_FUNC_RAND_UNLOCK, (void(*)(void))ossl_drbg_unlock },
518    { OSSL_FUNC_RAND_SETTABLE_CTX_PARAMS,
519      (void(*)(void))drbg_hash_settable_ctx_params },
520    { OSSL_FUNC_RAND_SET_CTX_PARAMS, (void(*)(void))drbg_hash_set_ctx_params },
521    { OSSL_FUNC_RAND_GETTABLE_CTX_PARAMS,
522      (void(*)(void))drbg_hash_gettable_ctx_params },
523    { OSSL_FUNC_RAND_GET_CTX_PARAMS, (void(*)(void))drbg_hash_get_ctx_params },
524    { OSSL_FUNC_RAND_VERIFY_ZEROIZATION,
525      (void(*)(void))drbg_hash_verify_zeroization },
526    { OSSL_FUNC_RAND_GET_SEED, (void(*)(void))ossl_drbg_get_seed },
527    { OSSL_FUNC_RAND_CLEAR_SEED, (void(*)(void))ossl_drbg_clear_seed },
528    { 0, NULL }
529};
530