/src/openssl31/providers/implementations/kdfs/sshkdf.c

Source (jump to first uncovered line)
/*
 * Copyright 2018-2022 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/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"

/* See RFC 4253, Section 7.2 */
static OSSL_FUNC_kdf_newctx_fn kdf_sshkdf_new;
static OSSL_FUNC_kdf_dupctx_fn kdf_sshkdf_dup;
static OSSL_FUNC_kdf_freectx_fn kdf_sshkdf_free;
static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;

static int SSHKDF(const EVP_MD *evp_md,
                  const unsigned char *key, size_t key_len,
                  const unsigned char *xcghash, size_t xcghash_len,
                  const unsigned char *session_id, size_t session_id_len,
                  char type, unsigned char *okey, size_t okey_len);

typedef struct {
    void *provctx;
    PROV_DIGEST digest;
    unsigned char *key; /* K */
    size_t key_len;
    unsigned char *xcghash; /* H */
    size_t xcghash_len;
    char type; /* X */
    unsigned char *session_id;
    size_t session_id_len;
} KDF_SSHKDF;

static void *kdf_sshkdf_new(void *provctx)
{
    KDF_SSHKDF *ctx;

    if (!ossl_prov_is_running())
        return NULL;

    if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
        ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
    else
        ctx->provctx = provctx;
    return ctx;
}

static void kdf_sshkdf_free(void *vctx)
{
    KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;

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

static void kdf_sshkdf_reset(void *vctx)
{
    KDF_SSHKDF *ctx = (KDF_SSHKDF *)vctx;
    void *provctx = ctx->provctx;

    ossl_prov_digest_reset(&ctx->digest);
    OPENSSL_clear_free(ctx->key, ctx->key_len);
    OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
    OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
    memset(ctx, 0, sizeof(*ctx));
    ctx->provctx = provctx;
}

static void *kdf_sshkdf_dup(void *vctx)
{
    const KDF_SSHKDF *src = (const KDF_SSHKDF *)vctx;
    KDF_SSHKDF *dest;

    dest = kdf_sshkdf_new(src->provctx);
    if (dest != NULL) {
        if (!ossl_prov_memdup(src->key, src->key_len,
                              &dest->key, &dest->key_len)
                || !ossl_prov_memdup(src->xcghash, src->xcghash_len,
                                     &dest->xcghash , &dest->xcghash_len)
                || !ossl_prov_memdup(src->session_id, src->session_id_len,
                                     &dest->session_id , &dest->session_id_len)
                || !ossl_prov_digest_copy(&dest->digest, &src->digest))
            goto err;
        dest->type = src->type;
    }
    return dest;

 err:
    kdf_sshkdf_free(dest);
    return NULL;
}

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

    if (!ossl_prov_is_running() || !kdf_sshkdf_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->key == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
        return 0;
    }
    if (ctx->xcghash == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
        return 0;
    }
    if (ctx->session_id == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
        return 0;
    }
    if (ctx->type == 0) {
        ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
        return 0;
    }
    return SSHKDF(md, ctx->key, ctx->key_len,
                  ctx->xcghash, ctx->xcghash_len,
                  ctx->session_id, ctx->session_id_len,
                  ctx->type, key, keylen);
}

static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
    const OSSL_PARAM *p;
    KDF_SSHKDF *ctx = vctx;
    OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);

    if (params == NULL)
        return 1;

    if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
        return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
        if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
            return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
        != NULL)
        if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
            return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
        != NULL)
        if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
            return 0;

    if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
        != NULL) {
        const char *kdftype;

        if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
            return 0;
        /* Expect one character (byte in this case) */
        if (kdftype == NULL || p->data_size != 1)
            return 0;
        if (kdftype[0] < 65 || kdftype[0] > 70) {
            ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
            return 0;
        }
        ctx->type = kdftype[0];
    }
    return 1;
}

static const OSSL_PARAM *kdf_sshkdf_settable_ctx_params(ossl_unused void *ctx,
                                                        ossl_unused void *p_ctx)
{
    static const OSSL_PARAM known_settable_ctx_params[] = {
        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
        OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
        OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
        OSSL_PARAM_END
    };
    return known_settable_ctx_params;
}

static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
{
    OSSL_PARAM *p;

    if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
        return OSSL_PARAM_set_size_t(p, SIZE_MAX);
    return -2;
}

static const OSSL_PARAM *kdf_sshkdf_gettable_ctx_params(ossl_unused void *ctx,
                                                        ossl_unused void *p_ctx)
{
    static const OSSL_PARAM known_gettable_ctx_params[] = {
        OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
        OSSL_PARAM_END
    };
    return known_gettable_ctx_params;
}

const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
    { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
    { OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_sshkdf_dup },
    { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
    { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
    { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
    { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
      (void(*)(void))kdf_sshkdf_settable_ctx_params },
    { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
    { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
      (void(*)(void))kdf_sshkdf_gettable_ctx_params },
    { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
    { 0, NULL }
};

static int SSHKDF(const EVP_MD *evp_md,
                  const unsigned char *key, size_t key_len,
                  const unsigned char *xcghash, size_t xcghash_len,
                  const unsigned char *session_id, size_t session_id_len,
                  char type, unsigned char *okey, size_t okey_len)
{
    EVP_MD_CTX *md = NULL;
    unsigned char digest[EVP_MAX_MD_SIZE];
    unsigned int dsize = 0;
    size_t cursize = 0;
    int ret = 0;

    md = EVP_MD_CTX_new();
    if (md == NULL)
        return 0;

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

    if (!EVP_DigestUpdate(md, key, key_len))
        goto out;

    if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
        goto out;

    if (!EVP_DigestUpdate(md, &type, 1))
        goto out;

    if (!EVP_DigestUpdate(md, session_id, session_id_len))
        goto out;

    if (!EVP_DigestFinal_ex(md, digest, &dsize))
        goto out;

    if (okey_len < dsize) {
        memcpy(okey, digest, okey_len);
        ret = 1;
        goto out;
    }

    memcpy(okey, digest, dsize);

    for (cursize = dsize; cursize < okey_len; cursize += dsize) {

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

        if (!EVP_DigestUpdate(md, key, key_len))
            goto out;

        if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
            goto out;

        if (!EVP_DigestUpdate(md, okey, cursize))
            goto out;

        if (!EVP_DigestFinal_ex(md, digest, &dsize))
            goto out;

        if (okey_len < cursize + dsize) {
            memcpy(okey + cursize, digest, okey_len - cursize);
            ret = 1;
            goto out;
        }

        memcpy(okey + cursize, digest, dsize);
    }

    ret = 1;

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


Coverage Report

Created: 2025-06-13 06:58

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2018-2022 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/core_names.h>
16		#include <openssl/proverr.h>
17		#include "internal/cryptlib.h"
18		#include "internal/numbers.h"
19		#include "crypto/evp.h"
20		#include "prov/provider_ctx.h"
21		#include "prov/providercommon.h"
22		#include "prov/implementations.h"
23		#include "prov/provider_util.h"
24
25		/* See RFC 4253, Section 7.2 */
26		static OSSL_FUNC_kdf_newctx_fn kdf_sshkdf_new;
27		static OSSL_FUNC_kdf_dupctx_fn kdf_sshkdf_dup;
28		static OSSL_FUNC_kdf_freectx_fn kdf_sshkdf_free;
29		static OSSL_FUNC_kdf_reset_fn kdf_sshkdf_reset;
30		static OSSL_FUNC_kdf_derive_fn kdf_sshkdf_derive;
31		static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_sshkdf_settable_ctx_params;
32		static OSSL_FUNC_kdf_set_ctx_params_fn kdf_sshkdf_set_ctx_params;
33		static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_sshkdf_gettable_ctx_params;
34		static OSSL_FUNC_kdf_get_ctx_params_fn kdf_sshkdf_get_ctx_params;
35
36		static int SSHKDF(const EVP_MD *evp_md,
37		const unsigned char *key, size_t key_len,
38		const unsigned char *xcghash, size_t xcghash_len,
39		const unsigned char *session_id, size_t session_id_len,
40		char type, unsigned char *okey, size_t okey_len);
41
42		typedef struct {
43		void *provctx;
44		PROV_DIGEST digest;
45		unsigned char key; / K */
46		size_t key_len;
47		unsigned char xcghash; / H */
48		size_t xcghash_len;
49		char type; /* X */
50		unsigned char *session_id;
51		size_t session_id_len;
52		} KDF_SSHKDF;
53
54		static void kdf_sshkdf_new(void provctx)
55	0	{
56	0	KDF_SSHKDF *ctx;
57
58	0	if (!ossl_prov_is_running())
59	0	return NULL;
60
61	0	if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
62	0	ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
63	0	else
64	0	ctx->provctx = provctx;
65	0	return ctx;
66	0	}
67
68		static void kdf_sshkdf_free(void *vctx)
69	25	{
70	25	KDF_SSHKDF ctx = (KDF_SSHKDF )vctx;
71
72	25	if (ctx != NULL) {
73	25	kdf_sshkdf_reset(ctx);
74	25	OPENSSL_free(ctx);
75	25	}
76	25	}
77
78		static void kdf_sshkdf_reset(void *vctx)
79	25	{
80	25	KDF_SSHKDF ctx = (KDF_SSHKDF )vctx;
81	25	void *provctx = ctx->provctx;
82
83	25	ossl_prov_digest_reset(&ctx->digest);
84	25	OPENSSL_clear_free(ctx->key, ctx->key_len);
85	25	OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
86	25	OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
87	25	memset(ctx, 0, sizeof(*ctx));
88	25	ctx->provctx = provctx;
89	25	}
90
91		static void kdf_sshkdf_dup(void vctx)
92	0	{
93	0	const KDF_SSHKDF src = (const KDF_SSHKDF )vctx;
94	0	KDF_SSHKDF *dest;
95
96	0	dest = kdf_sshkdf_new(src->provctx);
97	0	if (dest != NULL) {
98	0	if (!ossl_prov_memdup(src->key, src->key_len,
99	0	&dest->key, &dest->key_len)
100	0	\|\| !ossl_prov_memdup(src->xcghash, src->xcghash_len,
101	0	&dest->xcghash , &dest->xcghash_len)
102	0	\|\| !ossl_prov_memdup(src->session_id, src->session_id_len,
103	0	&dest->session_id , &dest->session_id_len)
104	0	\|\| !ossl_prov_digest_copy(&dest->digest, &src->digest))
105	0	goto err;
106	0	dest->type = src->type;
107	0	}
108	0	return dest;
109
110	0	err:
111	0	kdf_sshkdf_free(dest);
112	0	return NULL;
113	0	}
114
115		static int sshkdf_set_membuf(unsigned char *dst, size_t dst_len,
116		const OSSL_PARAM *p)
117	60	{
118	60	OPENSSL_clear_free(dst, dst_len);
119	60	*dst = NULL;
120	60	*dst_len = 0;
121	60	return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
122	60	}
123
124		static int kdf_sshkdf_derive(void vctx, unsigned char key, size_t keylen,
125		const OSSL_PARAM params[])
126	0	{
127	0	KDF_SSHKDF ctx = (KDF_SSHKDF )vctx;
128	0	const EVP_MD *md;
129
130	0	if (!ossl_prov_is_running() \|\| !kdf_sshkdf_set_ctx_params(ctx, params))
131	0	return 0;
132
133	0	md = ossl_prov_digest_md(&ctx->digest);
134	0	if (md == NULL) {
135	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
136	0	return 0;
137	0	}
138	0	if (ctx->key == NULL) {
139	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
140	0	return 0;
141	0	}
142	0	if (ctx->xcghash == NULL) {
143	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
144	0	return 0;
145	0	}
146	0	if (ctx->session_id == NULL) {
147	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
148	0	return 0;
149	0	}
150	0	if (ctx->type == 0) {
151	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
152	0	return 0;
153	0	}
154	0	return SSHKDF(md, ctx->key, ctx->key_len,
155	0	ctx->xcghash, ctx->xcghash_len,
156	0	ctx->session_id, ctx->session_id_len,
157	0	ctx->type, key, keylen);
158	0	}
159
160		static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
161	0	{
162	0	const OSSL_PARAM *p;
163	0	KDF_SSHKDF *ctx = vctx;
164	0	OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
165
166	0	if (params == NULL)
167	0	return 1;
168
169	0	if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
170	0	return 0;
171
172	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
173	0	if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
174	0	return 0;
175
176	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
177	0	!= NULL)
178	0	if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
179	0	return 0;
180
181	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
182	0	!= NULL)
183	0	if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
184	0	return 0;
185
186	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
187	0	!= NULL) {
188	0	const char *kdftype;
189
190	0	if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
191	0	return 0;
192		/* Expect one character (byte in this case) */
193	0	if (kdftype == NULL \|\| p->data_size != 1)
194	0	return 0;
195	0	if (kdftype[0] < 65 \|\| kdftype[0] > 70) {
196	0	ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
197	0	return 0;
198	0	}
199	0	ctx->type = kdftype[0];
200	0	}
201	0	return 1;
202	0	}
203
204		static const OSSL_PARAM kdf_sshkdf_settable_ctx_params(ossl_unused void ctx,
205		ossl_unused void *p_ctx)
206	25	{
207	25	static const OSSL_PARAM known_settable_ctx_params[] = {
208	25	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
209	25	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
210	25	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
211	25	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
212	25	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
213	25	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
214	25	OSSL_PARAM_END
215	25	};
216	25	return known_settable_ctx_params;
217	25	}
218
219		static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
220	0	{
221	0	OSSL_PARAM *p;
222
223	0	if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
224	0	return OSSL_PARAM_set_size_t(p, SIZE_MAX);
225	0	return -2;
226	0	}
227
228		static const OSSL_PARAM kdf_sshkdf_gettable_ctx_params(ossl_unused void ctx,
229		ossl_unused void *p_ctx)
230	0	{
231	0	static const OSSL_PARAM known_gettable_ctx_params[] = {
232	0	OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
233	0	OSSL_PARAM_END
234	0	};
235	0	return known_gettable_ctx_params;
236	0	}
237
238		const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
239		{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
240		{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_sshkdf_dup },
241		{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
242		{ OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
243		{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
244		{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
245		(void(*)(void))kdf_sshkdf_settable_ctx_params },
246		{ OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
247		{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
248		(void(*)(void))kdf_sshkdf_gettable_ctx_params },
249		{ OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
250		{ 0, NULL }
251		};
252
253		static int SSHKDF(const EVP_MD *evp_md,
254		const unsigned char *key, size_t key_len,
255		const unsigned char *xcghash, size_t xcghash_len,
256		const unsigned char *session_id, size_t session_id_len,
257		char type, unsigned char *okey, size_t okey_len)
258	0	{
259	0	EVP_MD_CTX *md = NULL;
260	0	unsigned char digest[EVP_MAX_MD_SIZE];
261	0	unsigned int dsize = 0;
262	0	size_t cursize = 0;
263	0	int ret = 0;
264
265	0	md = EVP_MD_CTX_new();
266	0	if (md == NULL)
267	0	return 0;
268
269	0	if (!EVP_DigestInit_ex(md, evp_md, NULL))
270	0	goto out;
271
272	0	if (!EVP_DigestUpdate(md, key, key_len))
273	0	goto out;
274
275	0	if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
276	0	goto out;
277
278	0	if (!EVP_DigestUpdate(md, &type, 1))
279	0	goto out;
280
281	0	if (!EVP_DigestUpdate(md, session_id, session_id_len))
282	0	goto out;
283
284	0	if (!EVP_DigestFinal_ex(md, digest, &dsize))
285	0	goto out;
286
287	0	if (okey_len < dsize) {
288	0	memcpy(okey, digest, okey_len);
289	0	ret = 1;
290	0	goto out;
291	0	}
292
293	0	memcpy(okey, digest, dsize);
294
295	0	for (cursize = dsize; cursize < okey_len; cursize += dsize) {
296
297	0	if (!EVP_DigestInit_ex(md, evp_md, NULL))
298	0	goto out;
299
300	0	if (!EVP_DigestUpdate(md, key, key_len))
301	0	goto out;
302
303	0	if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
304	0	goto out;
305
306	0	if (!EVP_DigestUpdate(md, okey, cursize))
307	0	goto out;
308
309	0	if (!EVP_DigestFinal_ex(md, digest, &dsize))
310	0	goto out;
311
312	0	if (okey_len < cursize + dsize) {
313	0	memcpy(okey + cursize, digest, okey_len - cursize);
314	0	ret = 1;
315	0	goto out;
316	0	}
317
318	0	memcpy(okey + cursize, digest, dsize);
319	0	}
320
321	0	ret = 1;
322
323	0	out:
324	0	EVP_MD_CTX_free(md);
325	0	OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
326	0	return ret;
327	0	}
328