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-rw-r--r--include/crypto/dh.h98
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diff --git a/include/crypto/dh.h b/include/crypto/dh.h
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+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Diffie-Hellman secret to be used with kpp API along with helper functions
+ *
+ * Copyright (c) 2016, Intel Corporation
+ * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
+ */
+#ifndef _CRYPTO_DH_
+#define _CRYPTO_DH_
+
+/**
+ * DOC: DH Helper Functions
+ *
+ * To use DH with the KPP cipher API, the following data structure and
+ * functions should be used.
+ *
+ * To use DH with KPP, the following functions should be used to operate on
+ * a DH private key. The packet private key that can be set with
+ * the KPP API function call of crypto_kpp_set_secret.
+ */
+
+/**
+ * struct dh - define a DH private key
+ *
+ * @key: Private DH key
+ * @p: Diffie-Hellman parameter P
+ * @g: Diffie-Hellman generator G
+ * @key_size: Size of the private DH key
+ * @p_size: Size of DH parameter P
+ * @g_size: Size of DH generator G
+ */
+struct dh {
+ const void *key;
+ const void *p;
+ const void *g;
+ unsigned int key_size;
+ unsigned int p_size;
+ unsigned int g_size;
+};
+
+/**
+ * crypto_dh_key_len() - Obtain the size of the private DH key
+ * @params: private DH key
+ *
+ * This function returns the packet DH key size. A caller can use that
+ * with the provided DH private key reference to obtain the required
+ * memory size to hold a packet key.
+ *
+ * Return: size of the key in bytes
+ */
+unsigned int crypto_dh_key_len(const struct dh *params);
+
+/**
+ * crypto_dh_encode_key() - encode the private key
+ * @buf: Buffer allocated by the caller to hold the packet DH
+ * private key. The buffer should be at least crypto_dh_key_len
+ * bytes in size.
+ * @len: Length of the packet private key buffer
+ * @params: Buffer with the caller-specified private key
+ *
+ * The DH implementations operate on a packet representation of the private
+ * key.
+ *
+ * Return: -EINVAL if buffer has insufficient size, 0 on success
+ */
+int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params);
+
+/**
+ * crypto_dh_decode_key() - decode a private key
+ * @buf: Buffer holding a packet key that should be decoded
+ * @len: Length of the packet private key buffer
+ * @params: Buffer allocated by the caller that is filled with the
+ * unpacked DH private key.
+ *
+ * The unpacking obtains the private key by pointing @p to the correct location
+ * in @buf. Thus, both pointers refer to the same memory.
+ *
+ * Return: -EINVAL if buffer has insufficient size, 0 on success
+ */
+int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params);
+
+/**
+ * __crypto_dh_decode_key() - decode a private key without parameter checks
+ * @buf: Buffer holding a packet key that should be decoded
+ * @len: Length of the packet private key buffer
+ * @params: Buffer allocated by the caller that is filled with the
+ * unpacked DH private key.
+ *
+ * Internal function providing the same services as the exported
+ * crypto_dh_decode_key(), but without any of those basic parameter
+ * checks conducted by the latter.
+ *
+ * Return: -EINVAL if buffer has insufficient size, 0 on success
+ */
+int __crypto_dh_decode_key(const char *buf, unsigned int len,
+ struct dh *params);
+
+#endif