/src/openssl/providers/implementations/kdfs/snmpkdf.c

Source
/*
 * Copyright 2025 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/kdf.h>
#include <openssl/sha.h>
#include <openssl/core_names.h>
#include <openssl/proverr.h>
#include "internal/cryptlib.h"
#include "internal/numbers.h"
#include "crypto/evp.h"
#include "prov/provider_ctx.h"
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_util.h"
#include "providers/implementations/kdfs/snmpkdf.inc"

#define KDF_SNMP_PASSWORD_HASH_AMOUNT (1024 * 1024)
#define KDF_SNMP_MIN_PASSWORD_LEN     8

/* See RFC 3414, Appendix A.2.2 */
/* See NIST SP800-135 Section 6.8 */
static OSSL_FUNC_kdf_newctx_fn kdf_snmpkdf_new;
static OSSL_FUNC_kdf_dupctx_fn kdf_snmpkdf_dup;
static OSSL_FUNC_kdf_freectx_fn kdf_snmpkdf_free;
static OSSL_FUNC_kdf_reset_fn kdf_snmpkdf_reset;
static OSSL_FUNC_kdf_derive_fn kdf_snmpkdf_derive;
static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_snmpkdf_settable_ctx_params;
static OSSL_FUNC_kdf_set_ctx_params_fn kdf_snmpkdf_set_ctx_params;
static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_snmpkdf_gettable_ctx_params;
static OSSL_FUNC_kdf_get_ctx_params_fn kdf_snmpkdf_get_ctx_params;

static int SNMPKDF(const EVP_MD *evp_md,
                   const unsigned char *eid, size_t eid_len,
                   unsigned char *password, size_t password_len,
                   unsigned char *key, size_t keylen);

typedef struct {
    /* Warning: Any changes to this structure may require you to update kdf_snmpkdf_dup */
    void *provctx;
    PROV_DIGEST digest;
    unsigned char *eid;
    size_t eid_len;
    unsigned char *password;
    size_t password_len;
} KDF_SNMPKDF;

static void *kdf_snmpkdf_new(void *provctx)
{
    KDF_SNMPKDF *ctx;

    if (!ossl_prov_is_running())
        return NULL;

    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
        ctx->provctx = provctx;
    return ctx;
}

static void *kdf_snmpkdf_dup(void *vctx)
{
    const KDF_SNMPKDF *src = (const KDF_SNMPKDF *)vctx;
    KDF_SNMPKDF *dest;

    dest = kdf_snmpkdf_new(src->provctx);
    if (dest != NULL) {
        if (!ossl_prov_memdup(src->eid, src->eid_len,
                              &dest->eid, &dest->eid_len)
                || !ossl_prov_memdup(src->password, src->password_len,
                                     &dest->password, &dest->password_len)
                || !ossl_prov_digest_copy(&dest->digest, &src->digest))
            goto err;
    }
    return dest;

 err:
    kdf_snmpkdf_free(dest);
    return NULL;
}

static void kdf_snmpkdf_free(void *vctx)
{
    KDF_SNMPKDF *ctx = (KDF_SNMPKDF *)vctx;

    if (ctx != NULL) {
        kdf_snmpkdf_reset(ctx);
        OPENSSL_free(ctx);
    }
}

static void kdf_snmpkdf_reset(void *vctx)
{
    KDF_SNMPKDF *ctx = (KDF_SNMPKDF *)vctx;
    void *provctx = ctx->provctx;

    ossl_prov_digest_reset(&ctx->digest);
    OPENSSL_clear_free(ctx->eid, ctx->eid_len);
    OPENSSL_clear_free(ctx->password, ctx->password_len);
    memset(ctx, 0, sizeof(*ctx));
    ctx->provctx = provctx;
}

static int snmpkdf_set_membuf(unsigned char **dst, size_t *dst_len,
                              const OSSL_PARAM *p)
{
    OPENSSL_clear_free(*dst, *dst_len);
    *dst = NULL;
    *dst_len = 0;
    return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
}

static int kdf_snmpkdf_derive(void *vctx, unsigned char *key, size_t keylen,
                              const OSSL_PARAM params[])
{
    KDF_SNMPKDF *ctx = (KDF_SNMPKDF *)vctx;
    const EVP_MD *md;

    if (!ossl_prov_is_running() || !kdf_snmpkdf_set_ctx_params(ctx, params))
        return 0;

    md = ossl_prov_digest_md(&ctx->digest);
    if (md == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
        return 0;
    }
    if (ctx->eid == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_EID);
        return 0;
    }
    if (ctx->password == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_PASS);
        return 0;
    }

    return SNMPKDF(md, ctx->eid, ctx->eid_len,
                   ctx->password, ctx->password_len,
                   key, keylen);
}

static int kdf_snmpkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
    struct snmp_set_ctx_params_st p;
    KDF_SNMPKDF *ctx = vctx;
    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
#ifdef FIPS_MODULE
    const EVP_MD *md = NULL;
#endif

    if (params == NULL)
        return 1;

    if (ctx == NULL || !snmp_set_ctx_params_decoder(params, &p))
        return 0;

    if (p.digest != NULL) {
        if (!ossl_prov_digest_load(&ctx->digest, p.digest, p.propq, libctx))
            return 0;
#ifdef FIPS_MODULE
        md = ossl_prov_digest_md(&ctx->digest);
        if (!EVP_MD_is_a(md, SN_sha1))
            return 0;
#endif
    }

    if (p.pw != NULL) {
        if (!snmpkdf_set_membuf(&ctx->password, &ctx->password_len, p.pw))
            return 0;
        if ((ctx->password_len > KDF_SNMP_PASSWORD_HASH_AMOUNT) ||
            (ctx->password_len < KDF_SNMP_MIN_PASSWORD_LEN))
            return 0;
    }

    if (p.eid != NULL && !snmpkdf_set_membuf(&ctx->eid, &ctx->eid_len, p.eid))
        return 0;

    return 1;
}

static const OSSL_PARAM *kdf_snmpkdf_settable_ctx_params(ossl_unused void *ctx,
                                                         ossl_unused void *p_ctx)
{
    return snmp_set_ctx_params_list;
}

static size_t kdf_snmpkdf_size(KDF_SNMPKDF *ctx)
{
    int len;
    const EVP_MD *md = NULL;

    md = ossl_prov_digest_md(&ctx->digest);
    if (md == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
        return 0;
    }
    len = EVP_MD_get_size(md);
    return (len <= 0) ? 0 : (size_t)len;
}

static int kdf_snmpkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
{
    struct snmp_get_ctx_params_st p;
    KDF_SNMPKDF *ctx = vctx;

    if (ctx == NULL || !snmp_get_ctx_params_decoder(params, &p))
        return 0;

    if (p.size != NULL) {
        size_t sz = kdf_snmpkdf_size(ctx);

        if (sz == 0)
            return 0;
        if (!OSSL_PARAM_set_size_t(p.size, sz))
            return 0;
    }
    return 1;
}

static const OSSL_PARAM *kdf_snmpkdf_gettable_ctx_params(ossl_unused void *ctx,
                                                         ossl_unused void *p_ctx)
{
    return snmp_get_ctx_params_list;
}

const OSSL_DISPATCH ossl_kdf_snmpkdf_functions[] = {
    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_snmpkdf_new },
    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_snmpkdf_dup },
    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_snmpkdf_free },
    { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_snmpkdf_reset },
    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_snmpkdf_derive },
    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
      (void(*)(void))kdf_snmpkdf_settable_ctx_params },
    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_snmpkdf_set_ctx_params },
    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
      (void(*)(void))kdf_snmpkdf_gettable_ctx_params },
    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_snmpkdf_get_ctx_params },
    { 0, NULL }
};

/*
 * SNMPKDF - In compliance with SP800-135 and RFC7860, calculate
 *           a master key using the engine ID and password.
 *
 * Denote engineLength and passwordlen to be the lengths (in bytes) of an
 * snmpEngineID and a password, respectively.
 *
 * Let N = (1024*1024)/passwordlen
 *
 * Expanded_password = the leftmost 1048576 bytes of the string of N
 * repetitions of the password.
 *
 * Derived_password = SHA-1 (Expanded_password). The Derived_password
 * is the output of hashing the Expanded_password by SHA-1.
 *
 * Let Shared_key to be the key that the user shares with the authoritative
 * SNMP engine with ID snmpEngineID. The Shared_key is generated as follows:
 *
 * Shared_key = SHA-1(Derived_password || snmpEngineID || Derived_password).
 *
 *     e_id -         engine ID(eid)
 *     e_len -        engineID length
 *     password -     password
 *     password_len - password length
 *     okey -         pointer to key output, FIPS testing limited to SHA-1.
 *     okeylen -      key output length
 *     return -       1 pass 0 for error
 */
static int SNMPKDF(const EVP_MD *evp_md,
                   const unsigned char *e_id, size_t e_len,
                   unsigned char *password, size_t password_len,
                   unsigned char *okey, size_t okeylen)
{
    EVP_MD_CTX *md = NULL;
    unsigned char digest[EVP_MAX_MD_SIZE];
    size_t mdsize = 0, len = 0;
    unsigned int md_len = 0;
    int ret = 0;

    /* Limited to SHA-1 and SHA-2 hashes presently */
    if (okey == NULL || okeylen == 0)
        return 0;

    md = EVP_MD_CTX_new();
    if (md == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
        goto err;
    }

    mdsize = EVP_MD_get_size(evp_md);
    if (mdsize <= 0 || mdsize < okeylen)
        goto err;

    if (!EVP_DigestInit_ex(md, evp_md, NULL))
        goto err;

    for (len = 0; len < KDF_SNMP_PASSWORD_HASH_AMOUNT - password_len; len += password_len) {
        if (!EVP_DigestUpdate(md, password, password_len))
            goto err;
    }

    if (!EVP_DigestUpdate(md, password, KDF_SNMP_PASSWORD_HASH_AMOUNT - len)
        || !EVP_DigestFinal_ex(md, digest, &md_len)
        || !EVP_DigestInit_ex(md, evp_md, NULL)
        || !EVP_DigestUpdate(md, digest, mdsize)
        || !EVP_DigestUpdate(md, e_id, e_len)
        || !EVP_DigestUpdate(md, digest, mdsize)
        || !EVP_DigestFinal_ex(md, digest, &md_len))
        goto err;

    memcpy(okey, digest, okeylen);

    ret = 1;

err:
    EVP_MD_CTX_free(md);
    OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
    return ret;
}

Coverage Report

Created: 2025-12-10 06:24

Line	Count	Source
1		/*
2		* Copyright 2025 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 <stdlib.h>
11		#include <stdarg.h>
12		#include <string.h>
13		#include <openssl/evp.h>
14		#include <openssl/kdf.h>
15		#include <openssl/sha.h>
16		#include <openssl/core_names.h>
17		#include <openssl/proverr.h>
18		#include "internal/cryptlib.h"
19		#include "internal/numbers.h"
20		#include "crypto/evp.h"
21		#include "prov/provider_ctx.h"
22		#include "prov/providercommon.h"
23		#include "prov/implementations.h"
24		#include "prov/provider_util.h"
25		#include "providers/implementations/kdfs/snmpkdf.inc"
26
27	0	#define KDF_SNMP_PASSWORD_HASH_AMOUNT (1024 * 1024)
28	0	#define KDF_SNMP_MIN_PASSWORD_LEN 8
29
30		/* See RFC 3414, Appendix A.2.2 */
31		/* See NIST SP800-135 Section 6.8 */
32		static OSSL_FUNC_kdf_newctx_fn kdf_snmpkdf_new;
33		static OSSL_FUNC_kdf_dupctx_fn kdf_snmpkdf_dup;
34		static OSSL_FUNC_kdf_freectx_fn kdf_snmpkdf_free;
35		static OSSL_FUNC_kdf_reset_fn kdf_snmpkdf_reset;
36		static OSSL_FUNC_kdf_derive_fn kdf_snmpkdf_derive;
37		static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_snmpkdf_settable_ctx_params;
38		static OSSL_FUNC_kdf_set_ctx_params_fn kdf_snmpkdf_set_ctx_params;
39		static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_snmpkdf_gettable_ctx_params;
40		static OSSL_FUNC_kdf_get_ctx_params_fn kdf_snmpkdf_get_ctx_params;
41
42		static int SNMPKDF(const EVP_MD *evp_md,
43		const unsigned char *eid, size_t eid_len,
44		unsigned char *password, size_t password_len,
45		unsigned char *key, size_t keylen);
46
47		typedef struct {
48		/* Warning: Any changes to this structure may require you to update kdf_snmpkdf_dup */
49		void *provctx;
50		PROV_DIGEST digest;
51		unsigned char *eid;
52		size_t eid_len;
53		unsigned char *password;
54		size_t password_len;
55		} KDF_SNMPKDF;
56
57		static void kdf_snmpkdf_new(void provctx)
58	0	{
59	0	KDF_SNMPKDF *ctx;
60
61	0	if (!ossl_prov_is_running())
62	0	return NULL;
63
64	0	if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
65	0	ctx->provctx = provctx;
66	0	return ctx;
67	0	}
68
69		static void kdf_snmpkdf_dup(void vctx)
70	0	{
71	0	const KDF_SNMPKDF src = (const KDF_SNMPKDF )vctx;
72	0	KDF_SNMPKDF *dest;
73
74	0	dest = kdf_snmpkdf_new(src->provctx);
75	0	if (dest != NULL) {
76	0	if (!ossl_prov_memdup(src->eid, src->eid_len,
77	0	&dest->eid, &dest->eid_len)
78	0	\|\| !ossl_prov_memdup(src->password, src->password_len,
79	0	&dest->password, &dest->password_len)
80	0	\|\| !ossl_prov_digest_copy(&dest->digest, &src->digest))
81	0	goto err;
82	0	}
83	0	return dest;
84
85	0	err:
86	0	kdf_snmpkdf_free(dest);
87	0	return NULL;
88	0	}
89
90		static void kdf_snmpkdf_free(void *vctx)
91	0	{
92	0	KDF_SNMPKDF ctx = (KDF_SNMPKDF )vctx;
93
94	0	if (ctx != NULL) {
95	0	kdf_snmpkdf_reset(ctx);
96	0	OPENSSL_free(ctx);
97	0	}
98	0	}
99
100		static void kdf_snmpkdf_reset(void *vctx)
101	0	{
102	0	KDF_SNMPKDF ctx = (KDF_SNMPKDF )vctx;
103	0	void *provctx = ctx->provctx;
104
105	0	ossl_prov_digest_reset(&ctx->digest);
106	0	OPENSSL_clear_free(ctx->eid, ctx->eid_len);
107	0	OPENSSL_clear_free(ctx->password, ctx->password_len);
108	0	memset(ctx, 0, sizeof(*ctx));
109	0	ctx->provctx = provctx;
110	0	}
111
112		static int snmpkdf_set_membuf(unsigned char *dst, size_t dst_len,
113		const OSSL_PARAM *p)
114	0	{
115	0	OPENSSL_clear_free(dst, dst_len);
116	0	*dst = NULL;
117	0	*dst_len = 0;
118	0	return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
119	0	}
120
121		static int kdf_snmpkdf_derive(void vctx, unsigned char key, size_t keylen,
122		const OSSL_PARAM params[])
123	0	{
124	0	KDF_SNMPKDF ctx = (KDF_SNMPKDF )vctx;
125	0	const EVP_MD *md;
126
127	0	if (!ossl_prov_is_running() \|\| !kdf_snmpkdf_set_ctx_params(ctx, params))
128	0	return 0;
129
130	0	md = ossl_prov_digest_md(&ctx->digest);
131	0	if (md == NULL) {
132	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
133	0	return 0;
134	0	}
135	0	if (ctx->eid == NULL) {
136	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_EID);
137	0	return 0;
138	0	}
139	0	if (ctx->password == NULL) {
140	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_PASS);
141	0	return 0;
142	0	}
143
144	0	return SNMPKDF(md, ctx->eid, ctx->eid_len,
145	0	ctx->password, ctx->password_len,
146	0	key, keylen);
147	0	}
148
149		static int kdf_snmpkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
150	0	{
151	0	struct snmp_set_ctx_params_st p;
152	0	KDF_SNMPKDF *ctx = vctx;
153	0	OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
154		#ifdef FIPS_MODULE
155		const EVP_MD *md = NULL;
156		#endif
157
158	0	if (params == NULL)
159	0	return 1;
160
161	0	if (ctx == NULL \|\| !snmp_set_ctx_params_decoder(params, &p))
162	0	return 0;
163
164	0	if (p.digest != NULL) {
165	0	if (!ossl_prov_digest_load(&ctx->digest, p.digest, p.propq, libctx))
166	0	return 0;
167		#ifdef FIPS_MODULE
168		md = ossl_prov_digest_md(&ctx->digest);
169		if (!EVP_MD_is_a(md, SN_sha1))
170		return 0;
171		#endif
172	0	}
173
174	0	if (p.pw != NULL) {
175	0	if (!snmpkdf_set_membuf(&ctx->password, &ctx->password_len, p.pw))
176	0	return 0;
177	0	if ((ctx->password_len > KDF_SNMP_PASSWORD_HASH_AMOUNT) \|\|
178	0	(ctx->password_len < KDF_SNMP_MIN_PASSWORD_LEN))
179	0	return 0;
180	0	}
181
182	0	if (p.eid != NULL && !snmpkdf_set_membuf(&ctx->eid, &ctx->eid_len, p.eid))
183	0	return 0;
184
185	0	return 1;
186	0	}
187
188		static const OSSL_PARAM kdf_snmpkdf_settable_ctx_params(ossl_unused void ctx,
189		ossl_unused void *p_ctx)
190	0	{
191	0	return snmp_set_ctx_params_list;
192	0	}
193
194		static size_t kdf_snmpkdf_size(KDF_SNMPKDF *ctx)
195	0	{
196	0	int len;
197	0	const EVP_MD *md = NULL;
198
199	0	md = ossl_prov_digest_md(&ctx->digest);
200	0	if (md == NULL) {
201	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
202	0	return 0;
203	0	}
204	0	len = EVP_MD_get_size(md);
205	0	return (len <= 0) ? 0 : (size_t)len;
206	0	}
207
208		static int kdf_snmpkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
209	0	{
210	0	struct snmp_get_ctx_params_st p;
211	0	KDF_SNMPKDF *ctx = vctx;
212
213	0	if (ctx == NULL \|\| !snmp_get_ctx_params_decoder(params, &p))
214	0	return 0;
215
216	0	if (p.size != NULL) {
217	0	size_t sz = kdf_snmpkdf_size(ctx);
218
219	0	if (sz == 0)
220	0	return 0;
221	0	if (!OSSL_PARAM_set_size_t(p.size, sz))
222	0	return 0;
223	0	}
224	0	return 1;
225	0	}
226
227		static const OSSL_PARAM kdf_snmpkdf_gettable_ctx_params(ossl_unused void ctx,
228		ossl_unused void *p_ctx)
229	0	{
230	0	return snmp_get_ctx_params_list;
231	0	}
232
233		const OSSL_DISPATCH ossl_kdf_snmpkdf_functions[] = {
234		{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_snmpkdf_new },
235		{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_snmpkdf_dup },
236		{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_snmpkdf_free },
237		{ OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_snmpkdf_reset },
238		{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_snmpkdf_derive },
239		{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
240		(void(*)(void))kdf_snmpkdf_settable_ctx_params },
241		{ OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_snmpkdf_set_ctx_params },
242		{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
243		(void(*)(void))kdf_snmpkdf_gettable_ctx_params },
244		{ OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_snmpkdf_get_ctx_params },
245		{ 0, NULL }
246		};
247
248		/*
249		* SNMPKDF - In compliance with SP800-135 and RFC7860, calculate
250		* a master key using the engine ID and password.
251		*
252		* Denote engineLength and passwordlen to be the lengths (in bytes) of an
253		* snmpEngineID and a password, respectively.
254		*
255		* Let N = (1024*1024)/passwordlen
256		*
257		* Expanded_password = the leftmost 1048576 bytes of the string of N
258		* repetitions of the password.
259		*
260		* Derived_password = SHA-1 (Expanded_password). The Derived_password
261		* is the output of hashing the Expanded_password by SHA-1.
262		*
263		* Let Shared_key to be the key that the user shares with the authoritative
264		* SNMP engine with ID snmpEngineID. The Shared_key is generated as follows:
265		*
266		* Shared_key = SHA-1(Derived_password \|\| snmpEngineID \|\| Derived_password).
267		*
268		* e_id - engine ID(eid)
269		* e_len - engineID length
270		* password - password
271		* password_len - password length
272		* okey - pointer to key output, FIPS testing limited to SHA-1.
273		* okeylen - key output length
274		* return - 1 pass 0 for error
275		*/
276		static int SNMPKDF(const EVP_MD *evp_md,
277		const unsigned char *e_id, size_t e_len,
278		unsigned char *password, size_t password_len,
279		unsigned char *okey, size_t okeylen)
280	0	{
281	0	EVP_MD_CTX *md = NULL;
282	0	unsigned char digest[EVP_MAX_MD_SIZE];
283	0	size_t mdsize = 0, len = 0;
284	0	unsigned int md_len = 0;
285	0	int ret = 0;
286
287		/* Limited to SHA-1 and SHA-2 hashes presently */
288	0	if (okey == NULL \|\| okeylen == 0)
289	0	return 0;
290
291	0	md = EVP_MD_CTX_new();
292	0	if (md == NULL) {
293	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
294	0	goto err;
295	0	}
296
297	0	mdsize = EVP_MD_get_size(evp_md);
298	0	if (mdsize <= 0 \|\| mdsize < okeylen)
299	0	goto err;
300
301	0	if (!EVP_DigestInit_ex(md, evp_md, NULL))
302	0	goto err;
303
304	0	for (len = 0; len < KDF_SNMP_PASSWORD_HASH_AMOUNT - password_len; len += password_len) {
305	0	if (!EVP_DigestUpdate(md, password, password_len))
306	0	goto err;
307	0	}
308
309	0	if (!EVP_DigestUpdate(md, password, KDF_SNMP_PASSWORD_HASH_AMOUNT - len)
310	0	\|\| !EVP_DigestFinal_ex(md, digest, &md_len)
311	0	\|\| !EVP_DigestInit_ex(md, evp_md, NULL)
312	0	\|\| !EVP_DigestUpdate(md, digest, mdsize)
313	0	\|\| !EVP_DigestUpdate(md, e_id, e_len)
314	0	\|\| !EVP_DigestUpdate(md, digest, mdsize)
315	0	\|\| !EVP_DigestFinal_ex(md, digest, &md_len))
316	0	goto err;
317
318	0	memcpy(okey, digest, okeylen);
319
320	0	ret = 1;
321
322	0	err:
323	0	EVP_MD_CTX_free(md);
324	0	OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
325	0	return ret;
326	0	}