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#ifndef THREEFISHAPI_H
#define THREEFISHAPI_H
/**
* @file threefishApi.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 Threefisch blocks only.
* Implementations for cipher modes such as ECB, CFB, or CBC may use these
* functions.
*
@code
// Threefish cipher context data
ThreefishKey_t keyCtx;
// Initialize the context
threefishSetKey(&keyCtx, Threefish512, key, tweak);
// Encrypt
threefishEncryptBlockBytes(&keyCtx, input, cipher);
@endcode
*/
#include <skein.h>
#include <stdint.h>
#define KeyScheduleConst 0x1BD11BDAA9FC1A22L
#ifdef __cplusplus
extern "C"
{
#endif
/**
* Which Threefish size to use
*/
typedef enum ThreefishSize {
Threefish256 = 256, /*!< Skein with 256 bit state */
Threefish512 = 512, /*!< Skein with 512 bit state */
Threefish1024 = 1024 /*!< Skein with 1024 bit state */
} ThreefishSize_t;
/**
* 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.
*/
typedef struct ThreefishKey {
u64b_t stateSize;
u64b_t key[SKEIN_MAX_STATE_WORDS+1]; /* max number of key words*/
u64b_t tweak[3];
} ThreefishKey_t;
/**
* 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 keyCtx
* Pointer to a Threefish key structure.
* @param size
* Which Skein size to use.
* @param keyData
* Pointer to the key words (word has 64 bits).
* @param tweak
* Pointer to the two tweak words (word has 64 bits).
*/
void threefishSetKey(ThreefishKey_t* keyCtx, ThreefishSize_t stateSize, uint64_t* keyData, uint64_t* tweak);
/**
* Encrypt Threefisch block (bytes).
*
* The buffer must have at least the same length (number of bits) aas the
* state size for this key. The function uses the first @c stateSize bits
* of the input buffer, encrypts them and stores the result in the output
* buffer.
*
* @param keyCtx
* Pointer to a Threefish key structure.
* @param in
* Poionter to plaintext data buffer.
* @param out
* Pointer to cipher buffer.
*/
void threefishEncryptBlockBytes(ThreefishKey_t* keyCtx, uint8_t* in, uint8_t* out);
/**
* Encrypt Threefisch block (words).
*
* The buffer must have at least the same length (number of bits) aas the
* state size for this key. The function uses the first @c stateSize bits
* of the input buffer, encrypts them and stores the result in the output
* buffer.
*
* The wordsize ist set to 64 bits.
*
* @param keyCtx
* Pointer to a Threefish key structure.
* @param in
* Poionter to plaintext data buffer.
* @param out
* Pointer to cipher buffer.
*/
void threefishEncryptBlockWords(ThreefishKey_t* keyCtx, uint64_t* in, uint64_t* out);
/**
* Decrypt Threefisch block (bytes).
*
* The buffer must have at least the same length (number of bits) aas the
* state size for this key. The function uses the first @c stateSize bits
* of the input buffer, decrypts them and stores the result in the output
* buffer
*
* @param keyCtx
* Pointer to a Threefish key structure.
* @param in
* Poionter to cipher data buffer.
* @param out
* Pointer to plaintext buffer.
*/
void threefishDecryptBlockBytes(ThreefishKey_t* keyCtx, uint8_t* in, uint8_t* out);
/**
* Decrypt Threefisch block (words).
*
* The buffer must have at least the same length (number of bits) aas the
* state size for this key. The function uses the first @c stateSize bits
* of the input buffer, encrypts them and stores the result in the output
* buffer.
*
* The wordsize ist set to 64 bits.
*
* @param keyCtx
* Pointer to a Threefish key structure.
* @param in
* Poionter to cipher data buffer.
* @param out
* Pointer to plaintext buffer.
*/
void threefishDecryptBlockWords(ThreefishKey_t* keyCtx, uint64_t* in, uint64_t* out);
void threefishEncrypt256(ThreefishKey_t* keyCtx, uint64_t* input, uint64_t* output);
void threefishEncrypt512(ThreefishKey_t* keyCtx, uint64_t* input, uint64_t* output);
void threefishEncrypt1024(ThreefishKey_t* keyCtx, uint64_t* input, uint64_t* output);
void threefishDecrypt256(ThreefishKey_t* keyCtx, uint64_t* input, uint64_t* output);
void threefishDecrypt512(ThreefishKey_t* keyCtx, uint64_t* input, uint64_t* output);
void threefishDecrypt1024(ThreefishKey_t* keyCtx, uint64_t* input, uint64_t* output);
#ifdef __cplusplus
}
#endif
/**
* @}
*/
#endif
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