/src/openssl32/providers/implementations/kdfs/sshkdf.c

Source (jump to first uncovered line)
/*
 * Copyright 2018-2023 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)
        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 },
    OSSL_DISPATCH_END
};

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 2018-2023 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	25	{
56	25	KDF_SSHKDF *ctx;
57
58	25	if (!ossl_prov_is_running())
59	0	return NULL;
60
61	25	if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) != NULL)
62	25	ctx->provctx = provctx;
63	25	return ctx;
64	25	}
65
66		static void kdf_sshkdf_free(void *vctx)
67	25	{
68	25	KDF_SSHKDF ctx = (KDF_SSHKDF )vctx;
69
70	25	if (ctx != NULL) {
71	25	kdf_sshkdf_reset(ctx);
72	25	OPENSSL_free(ctx);
73	25	}
74	25	}
75
76		static void kdf_sshkdf_reset(void *vctx)
77	25	{
78	25	KDF_SSHKDF ctx = (KDF_SSHKDF )vctx;
79	25	void *provctx = ctx->provctx;
80
81	25	ossl_prov_digest_reset(&ctx->digest);
82	25	OPENSSL_clear_free(ctx->key, ctx->key_len);
83	25	OPENSSL_clear_free(ctx->xcghash, ctx->xcghash_len);
84	25	OPENSSL_clear_free(ctx->session_id, ctx->session_id_len);
85	25	memset(ctx, 0, sizeof(*ctx));
86	25	ctx->provctx = provctx;
87	25	}
88
89		static void kdf_sshkdf_dup(void vctx)
90	0	{
91	0	const KDF_SSHKDF src = (const KDF_SSHKDF )vctx;
92	0	KDF_SSHKDF *dest;
93
94	0	dest = kdf_sshkdf_new(src->provctx);
95	0	if (dest != NULL) {
96	0	if (!ossl_prov_memdup(src->key, src->key_len,
97	0	&dest->key, &dest->key_len)
98	0	\|\| !ossl_prov_memdup(src->xcghash, src->xcghash_len,
99	0	&dest->xcghash , &dest->xcghash_len)
100	0	\|\| !ossl_prov_memdup(src->session_id, src->session_id_len,
101	0	&dest->session_id , &dest->session_id_len)
102	0	\|\| !ossl_prov_digest_copy(&dest->digest, &src->digest))
103	0	goto err;
104	0	dest->type = src->type;
105	0	}
106	0	return dest;
107
108	0	err:
109	0	kdf_sshkdf_free(dest);
110	0	return NULL;
111	0	}
112
113		static int sshkdf_set_membuf(unsigned char *dst, size_t dst_len,
114		const OSSL_PARAM *p)
115	60	{
116	60	OPENSSL_clear_free(dst, dst_len);
117	60	*dst = NULL;
118	60	*dst_len = 0;
119	60	return OSSL_PARAM_get_octet_string(p, (void **)dst, 0, dst_len);
120	60	}
121
122		static int kdf_sshkdf_derive(void vctx, unsigned char key, size_t keylen,
123		const OSSL_PARAM params[])
124	0	{
125	0	KDF_SSHKDF ctx = (KDF_SSHKDF )vctx;
126	0	const EVP_MD *md;
127
128	0	if (!ossl_prov_is_running() \|\| !kdf_sshkdf_set_ctx_params(ctx, params))
129	0	return 0;
130
131	0	md = ossl_prov_digest_md(&ctx->digest);
132	0	if (md == NULL) {
133	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
134	0	return 0;
135	0	}
136	0	if (ctx->key == NULL) {
137	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
138	0	return 0;
139	0	}
140	0	if (ctx->xcghash == NULL) {
141	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_XCGHASH);
142	0	return 0;
143	0	}
144	0	if (ctx->session_id == NULL) {
145	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SESSION_ID);
146	0	return 0;
147	0	}
148	0	if (ctx->type == 0) {
149	0	ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_TYPE);
150	0	return 0;
151	0	}
152	0	return SSHKDF(md, ctx->key, ctx->key_len,
153	0	ctx->xcghash, ctx->xcghash_len,
154	0	ctx->session_id, ctx->session_id_len,
155	0	ctx->type, key, keylen);
156	0	}
157
158		static int kdf_sshkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
159	0	{
160	0	const OSSL_PARAM *p;
161	0	KDF_SSHKDF *ctx = vctx;
162	0	OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
163
164	0	if (params == NULL)
165	0	return 1;
166
167	0	if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
168	0	return 0;
169
170	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)
171	0	if (!sshkdf_set_membuf(&ctx->key, &ctx->key_len, p))
172	0	return 0;
173
174	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_XCGHASH))
175	0	!= NULL)
176	0	if (!sshkdf_set_membuf(&ctx->xcghash, &ctx->xcghash_len, p))
177	0	return 0;
178
179	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_SESSION_ID))
180	0	!= NULL)
181	0	if (!sshkdf_set_membuf(&ctx->session_id, &ctx->session_id_len, p))
182	0	return 0;
183
184	0	if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SSHKDF_TYPE))
185	0	!= NULL) {
186	0	const char *kdftype;
187
188	0	if (!OSSL_PARAM_get_utf8_string_ptr(p, &kdftype))
189	0	return 0;
190		/* Expect one character (byte in this case) */
191	0	if (kdftype == NULL \|\| p->data_size != 1)
192	0	return 0;
193	0	if (kdftype[0] < 65 \|\| kdftype[0] > 70) {
194	0	ERR_raise(ERR_LIB_PROV, PROV_R_VALUE_ERROR);
195	0	return 0;
196	0	}
197	0	ctx->type = kdftype[0];
198	0	}
199	0	return 1;
200	0	}
201
202		static const OSSL_PARAM kdf_sshkdf_settable_ctx_params(ossl_unused void ctx,
203		ossl_unused void *p_ctx)
204	25	{
205	25	static const OSSL_PARAM known_settable_ctx_params[] = {
206	25	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
207	25	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
208	25	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
209	25	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_XCGHASH, NULL, 0),
210	25	OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SSHKDF_SESSION_ID, NULL, 0),
211	25	OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE, NULL, 0),
212	25	OSSL_PARAM_END
213	25	};
214	25	return known_settable_ctx_params;
215	25	}
216
217		static int kdf_sshkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
218	0	{
219	0	OSSL_PARAM *p;
220
221	0	if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
222	0	return OSSL_PARAM_set_size_t(p, SIZE_MAX);
223	0	return -2;
224	0	}
225
226		static const OSSL_PARAM kdf_sshkdf_gettable_ctx_params(ossl_unused void ctx,
227		ossl_unused void *p_ctx)
228	0	{
229	0	static const OSSL_PARAM known_gettable_ctx_params[] = {
230	0	OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
231	0	OSSL_PARAM_END
232	0	};
233	0	return known_gettable_ctx_params;
234	0	}
235
236		const OSSL_DISPATCH ossl_kdf_sshkdf_functions[] = {
237		{ OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_sshkdf_new },
238		{ OSSL_FUNC_KDF_DUPCTX, (void(*)(void))kdf_sshkdf_dup },
239		{ OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_sshkdf_free },
240		{ OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_sshkdf_reset },
241		{ OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_sshkdf_derive },
242		{ OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
243		(void(*)(void))kdf_sshkdf_settable_ctx_params },
244		{ OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_set_ctx_params },
245		{ OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
246		(void(*)(void))kdf_sshkdf_gettable_ctx_params },
247		{ OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_sshkdf_get_ctx_params },
248		OSSL_DISPATCH_END
249		};
250
251		static int SSHKDF(const EVP_MD *evp_md,
252		const unsigned char *key, size_t key_len,
253		const unsigned char *xcghash, size_t xcghash_len,
254		const unsigned char *session_id, size_t session_id_len,
255		char type, unsigned char *okey, size_t okey_len)
256	0	{
257	0	EVP_MD_CTX *md = NULL;
258	0	unsigned char digest[EVP_MAX_MD_SIZE];
259	0	unsigned int dsize = 0;
260	0	size_t cursize = 0;
261	0	int ret = 0;
262
263	0	md = EVP_MD_CTX_new();
264	0	if (md == NULL)
265	0	return 0;
266
267	0	if (!EVP_DigestInit_ex(md, evp_md, NULL))
268	0	goto out;
269
270	0	if (!EVP_DigestUpdate(md, key, key_len))
271	0	goto out;
272
273	0	if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
274	0	goto out;
275
276	0	if (!EVP_DigestUpdate(md, &type, 1))
277	0	goto out;
278
279	0	if (!EVP_DigestUpdate(md, session_id, session_id_len))
280	0	goto out;
281
282	0	if (!EVP_DigestFinal_ex(md, digest, &dsize))
283	0	goto out;
284
285	0	if (okey_len < dsize) {
286	0	memcpy(okey, digest, okey_len);
287	0	ret = 1;
288	0	goto out;
289	0	}
290
291	0	memcpy(okey, digest, dsize);
292
293	0	for (cursize = dsize; cursize < okey_len; cursize += dsize) {
294
295	0	if (!EVP_DigestInit_ex(md, evp_md, NULL))
296	0	goto out;
297
298	0	if (!EVP_DigestUpdate(md, key, key_len))
299	0	goto out;
300
301	0	if (!EVP_DigestUpdate(md, xcghash, xcghash_len))
302	0	goto out;
303
304	0	if (!EVP_DigestUpdate(md, okey, cursize))
305	0	goto out;
306
307	0	if (!EVP_DigestFinal_ex(md, digest, &dsize))
308	0	goto out;
309
310	0	if (okey_len < cursize + dsize) {
311	0	memcpy(okey + cursize, digest, okey_len - cursize);
312	0	ret = 1;
313	0	goto out;
314	0	}
315
316	0	memcpy(okey + cursize, digest, dsize);
317	0	}
318
319	0	ret = 1;
320
321	0	out:
322	0	EVP_MD_CTX_free(md);
323	0	OPENSSL_cleanse(digest, EVP_MAX_MD_SIZE);
324	0	return ret;
325	0	}
326