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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef THREEFISHAPI_H
#define THREEFISHAPI_H
/**
* @file threefish_api.h
* @brief A Threefish cipher API and its functions.
* @{
*
* This API and the functions that implement this API simplify the usage
* of the Threefish cipher. The design and the way to use the functions
* follow the openSSL design but at the same time take care of some Threefish
* specific behaviour and possibilities.
*
* These are the low level functions that deal with Threefish blocks only.
* Implementations for cipher modes such as ECB, CFB, or CBC may use these
* functions.
*
@code
// Threefish cipher context data
struct threefish_key key_ctx;
// Initialize the context
threefish_set_key(&key_ctx, THREEFISH_512, key, tweak);
// Encrypt
threefish_encrypt_block_bytes(&key_ctx, input, cipher);
@endcode
*/
#include <linux/types.h>
#include "skein_base.h"
#define KEY_SCHEDULE_CONST 0x1BD11BDAA9FC1A22L
/**
* Which Threefish size to use
*/
enum threefish_size {
THREEFISH_256 = 256, /*!< Skein with 256 bit state */
THREEFISH_512 = 512, /*!< Skein with 512 bit state */
THREEFISH_1024 = 1024 /*!< Skein with 1024 bit state */
};
/**
* Context for Threefish key and tweak words.
*
* This structure was setup with some know-how of the internal
* Skein structures, in particular ordering of header and size dependent
* variables. If Skein implementation changes this, the adapt these
* structures as well.
*/
struct threefish_key {
u64 state_size;
u64 key[SKEIN_MAX_STATE_WORDS + 1]; /* max number of key words*/
u64 tweak[3];
};
/**
* Set Threefish key and tweak data.
*
* This function sets the key and tweak data for the Threefish cipher of
* the given size. The key data must have the same length (number of bits)
* as the state size
*
* @param key_ctx
* Pointer to a Threefish key structure.
* @param size
* Which Skein size to use.
* @param key_data
* Pointer to the key words (word has 64 bits).
* @param tweak
* Pointer to the two tweak words (word has 64 bits).
*/
void threefish_set_key(struct threefish_key *key_ctx,
enum threefish_size state_size,
u64 *key_data, u64 *tweak);
/**
* Encrypt Threefish block (bytes).
*
* The buffer must have at least the same length (number of bits) as the
* state size for this key. The function uses the first @c state_size bits
* of the input buffer, encrypts them and stores the result in the output
* buffer.
*
* @param key_ctx
* Pointer to a Threefish key structure.
* @param in
* Poionter to plaintext data buffer.
* @param out
* Pointer to cipher buffer.
*/
void threefish_encrypt_block_bytes(struct threefish_key *key_ctx, u8 *in,
u8 *out);
/**
* Encrypt Threefish block (words).
*
* The buffer must have at least the same length (number of bits) as the
* state size for this key. The function uses the first @c state_size bits
* of the input buffer, encrypts them and stores the result in the output
* buffer.
*
* The wordsize ist set to 64 bits.
*
* @param key_ctx
* Pointer to a Threefish key structure.
* @param in
* Poionter to plaintext data buffer.
* @param out
* Pointer to cipher buffer.
*/
void threefish_encrypt_block_words(struct threefish_key *key_ctx, u64 *in,
u64 *out);
/**
* Decrypt Threefish block (bytes).
*
* The buffer must have at least the same length (number of bits) as the
* state size for this key. The function uses the first @c state_size bits
* of the input buffer, decrypts them and stores the result in the output
* buffer
*
* @param key_ctx
* Pointer to a Threefish key structure.
* @param in
* Poionter to cipher data buffer.
* @param out
* Pointer to plaintext buffer.
*/
void threefish_decrypt_block_bytes(struct threefish_key *key_ctx, u8 *in,
u8 *out);
/**
* Decrypt Threefish block (words).
*
* The buffer must have at least the same length (number of bits) as the
* state size for this key. The function uses the first @c state_size bits
* of the input buffer, encrypts them and stores the result in the output
* buffer.
*
* The wordsize ist set to 64 bits.
*
* @param key_ctx
* Pointer to a Threefish key structure.
* @param in
* Poionter to cipher data buffer.
* @param out
* Pointer to plaintext buffer.
*/
void threefish_decrypt_block_words(struct threefish_key *key_ctx, u64 *in,
u64 *out);
void threefish_encrypt_256(struct threefish_key *key_ctx, u64 *input,
u64 *output);
void threefish_encrypt_512(struct threefish_key *key_ctx, u64 *input,
u64 *output);
void threefish_encrypt_1024(struct threefish_key *key_ctx, u64 *input,
u64 *output);
void threefish_decrypt_256(struct threefish_key *key_ctx, u64 *input,
u64 *output);
void threefish_decrypt_512(struct threefish_key *key_ctx, u64 *input,
u64 *output);
void threefish_decrypt_1024(struct threefish_key *key_ctx, u64 *input,
u64 *output);
/**
* @}
*/
#endif
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