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142 lines
4.9 KiB
C
142 lines
4.9 KiB
C
/*
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* Copyright (C) 2013 Freie Universität Berlin, Computer Systems & Telematics
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup sys_crypto
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* @{
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*
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* @file
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* @brief Headers for the implementation of the SkipJack cipher-algorithm
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*
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* @author Freie Universitaet Berlin, Computer Systems & Telematics
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* @author Nicolai Schmittberger <nicolai.schmittberger@fu-berlin.de>
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* @author Zakaria Kasmi <zkasmi@inf.fu-berlin.de>
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*/
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#ifndef SKIPJACK_H_
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#define SKIPJACK_H_
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#include "crypto/ciphers.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define F(addr) /*CRYPTO_TABLE_ACCESS( &SJ_F[addr])*/ (SJ_F[addr])
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// G-Permutation: 4 round feistel structure
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#define G(key, b, bLeft, bRight) \
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( \
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bLeft = b, \
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bRight = (b >> 8), \
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bLeft ^= F(bRight ^ key[0]), \
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bRight ^= F(bLeft ^ key[1]), \
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bLeft ^= F(bRight ^ key[2]), \
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bRight ^= F(bLeft ^ key[3]), \
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((bRight << 8) | bLeft))
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#define G_INV(key, b, bLeft, bRight) \
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( bLeft = b, \
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bRight = (b >> 8), \
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bRight ^= F(bLeft ^ key[3]), \
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bLeft ^= F(bRight ^ key[2]), \
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bRight ^= F(bLeft ^ key[1]), \
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bLeft ^= F(bRight ^ key[0]), \
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((bRight << 8) | bLeft))
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// A-RULE:
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#define RULE_A(skey, w1, w2, w3, w4, counter, tmp, bLeft, bRight ) { \
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tmp = w4; \
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w4 = w3; \
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w3 = w2; \
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w2 = G(skey, w1, bLeft, bRight); \
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w1 = ((tmp ^ w2) ^ counter); \
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counter++; \
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skey += 4; }
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#define RULE_A_INV(skey, w1, w2, w3, w4, counter, tmp, bLeft, bRight) { \
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tmp = w4; \
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w4 = (w1 ^ w2 ^ counter); \
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w1 = G_INV(skey, w2, bLeft, bRight); \
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w2 = w3; \
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w3 = tmp; \
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counter--; \
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skey -= 4; } \
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// B-RULE:
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#define RULE_B(skey, w1, w2, w3, w4, counter, tmp, bLeft, bRight ) { \
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tmp = w1; \
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w1 = w4; \
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w4 = w3; \
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w3 = (tmp ^ w2 ^ counter); \
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w2 = G(skey, tmp, bLeft, bRight); \
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counter++; \
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skey += 4; }
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#define RULE_B_INV(skey, w1, w2, w3, w4, counter, tmp, bLeft, bRight ) { \
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tmp = w1; \
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w1 = G_INV(skey, w2, bLeft, bRight); \
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w2 = (w1 ^ w3 ^ counter); \
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w3 = w4; \
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w4 = tmp; \
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counter--; \
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skey -= 4; }
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/** 2 times keysize. makes unrolling keystream easier / efficient */
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#define SKIPJACK_CONTEXT_SIZE 20
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/**
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* @brief Initialize the SkipJack-BlockCipher context.
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*
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* @param context structure to hold the opaque data from this
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* initialization call. It should be passed to future
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* invocations of this module which use this particular
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* key.
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* @param keySize key size in bytes
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* @param key pointer to the key
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*
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* @return Whether initialization was successful. The command may be
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* unsuccessful if the key size is not valid.
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*/
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int skipjack_init(cipher_context_t *context, const uint8_t *key, uint8_t keySize);
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/**
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* @brief Encrypts a single block (of blockSize) using the passed context.
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*
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* @param context holds the module specific opaque data related to the
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* key (perhaps key expansions).
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* @param plainBlock a plaintext block of blockSize
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* @param cipherBlock the resulting ciphertext block of blockSize
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*
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* @return Whether the encryption was successful. Possible failure reasons
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* include not calling init().
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*/
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int skipjack_encrypt(const cipher_context_t *context, const uint8_t *plainBlock,
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uint8_t *cipherBlock);
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/**
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* @brief Decrypts a single block (of blockSize) using the passed context.
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*
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* @param context holds the module specific opaque data related to the
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* key (perhaps key expansions).
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* @param cipherBlock a ciphertext block of blockSize
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* @param plainBlock the resulting plaintext block of blockSize
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*
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* @return Whether the decryption was successful. Possible failure reasons
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* include not calling init()
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*/
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int skipjack_decrypt(const cipher_context_t *context, const uint8_t *cipherBlock,
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uint8_t *plainBlock);
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#ifdef __cplusplus
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}
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#endif
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/** @} */
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#endif /* SKIPJACK_H_ */
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