crypto: Add interface for key derivation functions

src/libstrongswan/Android.mk

@@ -17,7 +17,7 @@ crypto/prf_plus.c crypto/signers/signer.c \
 crypto/signers/mac_signer.c crypto/crypto_factory.c crypto/crypto_tester.c \
 crypto/diffie_hellman.c crypto/aead.c crypto/transform.c \
 crypto/iv/iv_gen.c crypto/iv/iv_gen_rand.c crypto/iv/iv_gen_seq.c \
-crypto/iv/iv_gen_null.c \
+crypto/iv/iv_gen_null.c crypto/kdfs/kdf.c \
 crypto/xofs/xof.c crypto/xofs/xof_bitspender.c \
 credentials/credential_factory.c credentials/builder.c \
 credentials/cred_encoding.c credentials/keys/private_key.c \

src/libstrongswan/Makefile.am

@@ -15,7 +15,7 @@ crypto/prf_plus.c crypto/signers/signer.c \
 crypto/signers/mac_signer.c crypto/crypto_factory.c crypto/crypto_tester.c \
 crypto/diffie_hellman.c crypto/aead.c crypto/transform.c \
 crypto/iv/iv_gen.c crypto/iv/iv_gen_rand.c crypto/iv/iv_gen_seq.c \
-crypto/iv/iv_gen_null.c \
+crypto/iv/iv_gen_null.c crypto/kdfs/kdf.c \
 crypto/xofs/xof.c crypto/xofs/xof_bitspender.c \
 credentials/credential_factory.c credentials/builder.c \
 credentials/cred_encoding.c credentials/keys/private_key.c \
@@ -83,6 +83,7 @@ crypto/crypto_factory.h crypto/crypto_tester.h crypto/diffie_hellman.h \
 crypto/aead.h crypto/transform.h crypto/pkcs5.h crypto/iv/iv_gen.h \
 crypto/iv/iv_gen_rand.h crypto/iv/iv_gen_seq.h crypto/iv/iv_gen_null.h \
 crypto/xofs/xof.h crypto/xofs/xof_bitspender.h crypto/xofs/mgf1.h \
+crypto/kdfs/kdf.h \
 credentials/credential_factory.h credentials/builder.h \
 credentials/cred_encoding.h credentials/keys/private_key.h \
 credentials/keys/public_key.h credentials/keys/shared_key.h \

src/libstrongswan/crypto/kdfs/kdf.c

@@ -0,0 +1,28 @@
+/*
+ * 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 "kdf.h"
+
+ENUM(key_derivation_function_names, KDF_UNDEFINED, KDF_PRF_PLUS,
+	"KDF_UNDEFINED",
+	"KDF_PRF_PLUS",
+);

src/libstrongswan/crypto/kdfs/kdf.h

@@ -0,0 +1,124 @@
+/*
+ * 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.
+ */
+
+/**
+ * @defgroup kdf kdf
+ * @{ @ingroup crypto
+ */
+
+#ifndef KDF_H_
+#define KDF_H_
+
+typedef enum key_derivation_function_t key_derivation_function_t;
+typedef enum kdf_param_t kdf_param_t;
+typedef struct kdf_t kdf_t;
+
+#include <library.h>
+
+/**
+ * Key Derivation Functions (KDF).
+ */
+enum key_derivation_function_t {
+
+	KDF_UNDEFINED,
+
+	/**
+	 * RFC 7296 prf+, expects a pseudo_random_function_t in the constructor,
+	 * parameters are KEY and SALT.
+	 */
+	KDF_PRF_PLUS,
+};
+
+/**
+ * enum name for key_derivation_function_t.
+ */
+extern enum_name_t *key_derivation_function_names;
+
+/**
+ * Parameters for KDFs.
+ */
+enum kdf_param_t {
+
+	/**
+	 * Key used for the key derivation (chunk_t).
+	 */
+	KDF_PARAM_KEY,
+
+	/**
+	 * Salt used for the key derivation (chunk_t).
+	 */
+	KDF_PARAM_SALT,
+};
+
+/**
+ * Generic interface for Key Derivation Functions (KDF).
+ *
+ * Note that in comparison to xof_t, this interface does not support streaming.
+ * That is, calling get_bytes() or allocate_bytes() multiple times without
+ * changing the input parameters will result in the same output.
+ */
+struct kdf_t {
+
+	/**
+	 * Return the type of KDF.
+	 *
+	 * @return			KDF type
+	 */
+	key_derivation_function_t (*get_type)(kdf_t *this);
+
+	/**
+	 * Derives a key of the given length and writes it to the buffer.
+	 *
+	 * @param out_len	number of key bytes requested
+	 * @param buffer	pointer where the derived key will be written
+	 * @return			TRUE if key derived successfully
+	 */
+	bool (*get_bytes)(kdf_t *this, size_t out_len,
+					  uint8_t *buffer) __attribute__((warn_unused_result));
+
+	/**
+	 * Derives a key of the given length and allocates space for it.
+	 *
+	 * @param out_len	number of key bytes requested
+	 * @param chunk		chunk which will hold the derived key
+	 * @return			TRUE if key derived successfully
+	 */
+	bool (*allocate_bytes)(kdf_t *this, size_t out_len,
+						   chunk_t *chunk) __attribute__((warn_unused_result));
+
+	/**
+	 * Set a parameter for this KDF.
+	 *
+	 * @param param		parameter to set
+	 * @param ...		parameter values
+	 * @return			TRUE if parameter set successfully
+	 */
+	bool (*set_param)(kdf_t *this, kdf_param_t param,
+					 ...) __attribute__((warn_unused_result));
+
+	/**
+	 * Destroys this KDF object.
+	 */
+	void (*destroy)(kdf_t *this);
+};
+
+#endif /** KDF_H_ @}*/