wolfssl: Implement prf+ via wolfSSL's HKDF implementation

src/libstrongswan/plugins/wolfssl/wolfssl_kdf.c

@@ -0,0 +1,161 @@
+/*
+ * Copyright (C) 2022 Tobias Brunner, codelabs GmbH
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "wolfssl_common.h"
+
+#if !defined(NO_HMAC) && defined(HAVE_HKDF)
+
+#include <wolfssl/wolfcrypt/hmac.h>
+
+#define _GNU_SOURCE
+#include "wolfssl_kdf.h"
+#include "wolfssl_util.h"
+
+typedef struct private_kdf_t private_kdf_t;
+
+/**
+ * Private data.
+ */
+struct private_kdf_t {
+
+	/**
+	 * Public interface.
+	 */
+	kdf_t public;
+
+	/**
+	 * Hash algorithm type.
+	 */
+	int type;
+
+	/**
+	 * Key for KDF.
+	 */
+	chunk_t key;
+
+	/**
+	 * Salt for KDF.
+	 */
+	chunk_t salt;
+};
+
+METHOD(kdf_t, get_type, key_derivation_function_t,
+	private_kdf_t *this)
+{
+	return KDF_PRF_PLUS;
+}
+
+METHOD(kdf_t, get_bytes, bool,
+	private_kdf_t *this, size_t out_len, uint8_t *buffer)
+{
+	if (wc_HKDF_Expand(this->type, this->key.ptr, this->key.len,
+					   this->salt.ptr, this->salt.len, buffer, out_len))
+	{
+		return FALSE;
+	}
+	return TRUE;
+}
+
+METHOD(kdf_t, allocate_bytes, bool,
+	private_kdf_t *this, size_t out_len, chunk_t *chunk)
+{
+	*chunk = chunk_alloc(out_len);
+
+	if (!get_bytes(this, out_len, chunk->ptr))
+	{
+		chunk_free(chunk);
+		return FALSE;
+	}
+	return TRUE;
+}
+
+METHOD(kdf_t, set_param, bool,
+	private_kdf_t *this, kdf_param_t param, ...)
+{
+	chunk_t chunk;
+
+	switch (param)
+	{
+		case KDF_PARAM_KEY:
+			VA_ARGS_GET(param, chunk);
+			chunk_clear(&this->key);
+			this->key = chunk_clone(chunk);
+			break;
+		case KDF_PARAM_SALT:
+			VA_ARGS_GET(param, chunk);
+			chunk_clear(&this->salt);
+			this->salt = chunk_clone(chunk);
+			break;
+	}
+	return TRUE;
+}
+
+METHOD(kdf_t, destroy, void,
+	private_kdf_t *this)
+{
+	chunk_clear(&this->salt);
+	chunk_clear(&this->key);
+	free(this);
+}
+
+/*
+ * Described in header
+ */
+kdf_t *wolfssl_kdf_create(key_derivation_function_t algo, va_list args)
+{
+	private_kdf_t *this;
+	pseudo_random_function_t prf_alg;
+	enum wc_HashType type;
+	char buf[8];
+
+	if (algo != KDF_PRF_PLUS)
+	{
+		return NULL;
+	}
+
+	VA_ARGS_VGET(args, prf_alg);
+	if (!wolfssl_hash2type(hasher_algorithm_from_prf(prf_alg), &type))
+	{
+		return NULL;
+	}
+
+	INIT(this,
+		.public = {
+			.get_type = _get_type,
+			.get_bytes = _get_bytes,
+			.allocate_bytes = _allocate_bytes,
+			.set_param = _set_param,
+			.destroy = _destroy,
+		},
+		.type = type,
+	);
+
+	/* test if we can actually use the algorithm */
+	if (!get_bytes(this, sizeof(buf), buf))
+	{
+		destroy(this);
+		return NULL;
+	}
+	return &this->public;
+}
+
+#endif /* !NO_HMAC && HAVE_HKDF */