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| [svn] / ecrypt / trunk / submissions / dragon / dragon.c |
* removed the `ctx->full_rekeying' mechanism to make the code conform to the API. * moved `ctx->nlfsr_offset = 0' from `ECRYPT_keysetup' to `ECRYPT_ivsetup'. * corrected a few bugs in the buffering mechanism.
/**
* @file dragon-ref.c
* Implementation of Dragon
* This source is provided without warranty
* or guarantee of any kind. Use at your own risk.
* @author Information Security Institute
*/
#include <assert.h>
#include "ecrypt-sync.h"
#include "ecrypt-portable.h"
#include "dragon-sboxes.c"
/**
* The DRAGON_OFFSET macro calculates the position of the
* ith_element within the circular buffer that represents the
* NLFSR.
*/
#define DRAGON_OFFSET(ctx, ith_element, state_size) \
((ctx->nlfsr_offset + ith_element) & state_size)
/**
* The DRAGON_NLFSR_WORD macro retrieves the ith 32-bit word
* from the Dragon NLFSR.
*/
#define DRAGON_NLFSR_WORD(ctx, ith_word) \
*(ctx->nlfsr_word + DRAGON_OFFSET(ctx, ith_word, (DRAGON_NLFSR_SIZE - 1)))
/**
* The Dragon update function consists of a pre-mixing, post-mixing and s-box
* layer. The pre- and post-mixing in turn consist of one XOR layer and one
* ADD layer. The s-box layer contains two sublayers, one which uses three G
* s-boxes, and the other which uses three H s-boxes.
*/
#define XOR_LAYER(d1, s1, d2, s2, d3, s3) \
d1 ^= s1; \
d2 ^= s2; \
d3 ^= s3;
#define ADD_LAYER(d1, s1, d2, s2, d3, s3) \
d1 += s1; \
d2 += s2; \
d3 += s3; \
#define SBOX_LAYER(sbox, d1, s1, d2, s2, d3, s3) \
d1 ^= sbox##1(s1); \
d2 ^= sbox##2(s2); \
d3 ^= sbox##3(s3);
#define DRAGON_UPDATE(a, b, c, d, e, f) \
XOR_LAYER(b, a, d, c, f, e) \
ADD_LAYER(c, b, e, d, a, f) \
SBOX_LAYER(G, d, a, f, c, b, e) \
SBOX_LAYER(H, a, b, c, d, e, f) \
ADD_LAYER(f, c, b, e, d, a) \
XOR_LAYER(a, f, c, b, e, d)
/*
* Key and message independent initialization. This function will be
* called once when the program starts (e.g., to build expanded S-box
* tables).
*/
void ECRYPT_init(void)
{
}
/*
* Key setup. It is the user's responsibility to select the values of
* keysize and ivsize from the set of supported values specified
* above.
*/
void ECRYPT_keysetup(
ECRYPT_ctx* ctx,
const u8* key,
u32 keysize, /* Key size in bits. */
u32 ivsize) /* IV size in bits. */
{
u32 idx;
u32 key_word;
assert(ctx && key);
ctx->key_size = keysize;
/**
* Dragon supports the following combinations of key and IV sizes only:
* (128, 128) and (256, 256) bits. Mix and matching is not supported,
* nor are other sizes. The ivsize parameter is ignored here.
*/
if (keysize == 128)
{
/* For a keysize of 128 bits, the Dragon NLFSR is initialized
using K and IV as follows (where k' and iv' represent
swapping of halves of key and iv respectively):
k | k' ^ iv' | iv | (k ^ iv') | k' | (k ^ iv) | iv' | (k' ^ iv)
*/
for (idx = 0; idx < 4; idx++) {
key_word = U8TO32_BIG(key + idx * 4);
ctx->nlfsr_word[0+idx] = ctx->nlfsr_word[12+idx] =
ctx->nlfsr_word[20+idx] = key_word;
}
/* then write k' */
for (idx = 0; idx < 2; idx++) {
key_word = U8TO32_BIG(key + 8 + idx * 4 );
ctx->nlfsr_word[4+idx] = ctx->nlfsr_word[16+idx] =
ctx->nlfsr_word[28+idx] = key_word;
key_word = U8TO32_BIG(key + idx * 4);
ctx->nlfsr_word[6+idx] = ctx->nlfsr_word[18+idx] =
ctx->nlfsr_word[30+idx] = key_word;
}
}
else
{
/* For a keysize of 256 bits, the Dragon NLFSR is initialized
using K and IV as follows (where {k} and {iv} represent
the bitwise complements of keys and ivs repsectively:
k | k ^ iv | {k ^ iv} | iv
*/
for (idx = 0; idx < 8; idx++) {
key_word = U8TO32_BIG(key + idx * 4);
ctx->nlfsr_word[0+idx] = ctx->nlfsr_word[8+idx] = key_word;
ctx->nlfsr_word[16+idx] = key_word;
}
}
/* Preserve the state for the key-IV-IV-... scenario described below
*/
for (idx = 0; idx < DRAGON_NLFSR_SIZE; idx++) {
ctx->init_state[idx] = ctx->nlfsr_word[idx];
}
}
#define DRAGON_MIXING_STAGES 16 /* number of mixes during initialization */
/*
* IV setup. After having called ECRYPT_keysetup(), the user is
* allowed to call ECRYPT_ivsetup() different times in order to
* encrypt/decrypt different messages with the same key but different
* IV's.
*/
void ECRYPT_ivsetup(
ECRYPT_ctx* ctx,
const u8* iv)
{
u32 a, b, c, d;
u32 e = 0x00004472;
u32 f = 0x61676F6E;
u32 iv_word;
u32 idx;
assert(ctx && iv);
/**
* Restore the state to the post-keysetup state.
*/
for (idx = 0; idx < DRAGON_NLFSR_SIZE; idx++) {
ctx->nlfsr_word[idx] = ctx->init_state[idx];
}
/* For a keysize of 128 bits, the Dragon NLFSR is initialized
using K and IV as follows (where k' and iv' represent
swapping of halves of key and iv respectively):
k | k' ^ iv' | iv | k ^ iv' | k' | k ^ iv | iv' | k' ^ iv
Therefore initialization of locations {0, 1, 8, 9} are
deliberately omitted here, as the iv is not involved.
*/
if (ctx->key_size == 128)
{
/* write iv first */
for (idx = 0; idx < 4; idx++) {
iv_word = U8TO32_BIG(iv + idx * 4);
ctx->nlfsr_word[8+idx] = iv_word;
ctx->nlfsr_word[20+idx] ^= iv_word;
ctx->nlfsr_word[28+idx] ^= iv_word;
}
/* then iv' */
for (idx = 0; idx < 2; idx++) {
iv_word = U8TO32_BIG(iv + 8 + idx * 4);
ctx->nlfsr_word[ 4+idx] ^= iv_word;
ctx->nlfsr_word[12+idx] ^= iv_word;
ctx->nlfsr_word[24+idx] = iv_word;
iv_word = U8TO32_BIG(iv + idx * 4);
ctx->nlfsr_word[ 6+idx] ^= iv_word;
ctx->nlfsr_word[14+idx] ^= iv_word;
ctx->nlfsr_word[26+idx] = iv_word;
}
}
else
{
/* For a keysize of 256 bits, the Dragon NLFSR is initialized
using K and IV as follows (where {k} and {iv} represent
the bitwise complements of keys and ivs repsectively:
k | (k ^ iv) | {k ^ iv} | iv
*/
for (idx = 0; idx < 8; idx++) {
iv_word = U8TO32_BIG(iv + idx * 4);
ctx->nlfsr_word[ 8 + idx] ^= iv_word;
ctx->nlfsr_word[16 + idx] ^= (iv_word ^ 0xFFFFFFFF);
ctx->nlfsr_word[24 + idx] = iv_word;
}
}
ctx->nlfsr_offset = 0;
/** Iterate mixing process */
for (idx = 0; idx < DRAGON_MIXING_STAGES; idx++) {
a = DRAGON_NLFSR_WORD(ctx, 0) ^
DRAGON_NLFSR_WORD(ctx, 24) ^
DRAGON_NLFSR_WORD(ctx, 28);
b = DRAGON_NLFSR_WORD(ctx, 1) ^
DRAGON_NLFSR_WORD(ctx, 25) ^
DRAGON_NLFSR_WORD(ctx, 29);
c = DRAGON_NLFSR_WORD(ctx, 2) ^
DRAGON_NLFSR_WORD(ctx, 26) ^
DRAGON_NLFSR_WORD(ctx, 30);
d = DRAGON_NLFSR_WORD(ctx, 3) ^
DRAGON_NLFSR_WORD(ctx, 27) ^
DRAGON_NLFSR_WORD(ctx, 31);
DRAGON_UPDATE(a, b, c, d, e, f);
ctx->nlfsr_offset += (DRAGON_NLFSR_SIZE - 4);
DRAGON_NLFSR_WORD(ctx, 0) = a ^ DRAGON_NLFSR_WORD(ctx, 20);
DRAGON_NLFSR_WORD(ctx, 1) = b ^ DRAGON_NLFSR_WORD(ctx, 21);
DRAGON_NLFSR_WORD(ctx, 2) = c ^ DRAGON_NLFSR_WORD(ctx, 22);
DRAGON_NLFSR_WORD(ctx, 3) = d ^ DRAGON_NLFSR_WORD(ctx, 23);
}
ctx->state_counter = ((u64)e << 32) | (u64)f;
/* reset buffer index */
ctx->buffer_index = 0;
}
/**
* DRAGON_ROUND produces one block of keystream
*/
#define DRAGON_ROUND(ctx, a, b, c, d, e, f) \
a = DRAGON_NLFSR_WORD(ctx, 0); \
b = DRAGON_NLFSR_WORD(ctx, 9); \
c = DRAGON_NLFSR_WORD(ctx, 16); \
d = DRAGON_NLFSR_WORD(ctx, 19); \
e = DRAGON_NLFSR_WORD(ctx, 30) ^ U32V(ctx->state_counter >> 32); \
f = DRAGON_NLFSR_WORD(ctx, 31) ^ U32V(ctx->state_counter); \
DRAGON_UPDATE(a, b, c, d, e, f); \
ctx->state_counter++; \
ctx->nlfsr_offset -= 2; \
DRAGON_NLFSR_WORD(ctx, 0) = b;\
DRAGON_NLFSR_WORD(ctx, 1) = c;
/**
* Generate #(blocks) 64-bit blocks of keystream.
* @param ctx [In/Out] Dragon context
* @param keystream [Out] pre-allocated array containing 8*(blocks)
* bytes of memory
* @param blocks [In] number of keystream blocks to produce
*/
void ECRYPT_keystream_blocks(
ECRYPT_ctx* ctx,
u8* keystream,
u32 blocks)
{
u32 *k_ptr = (u32*)keystream;
u32 a, b, c, d, e, f;
assert(ctx && keystream);
while (blocks > 0) {
DRAGON_ROUND(ctx, a, b, c, d, e, f)
*(k_ptr++) = U32TO32_BIG(a);
*(k_ptr++) = U32TO32_BIG(e);
blocks--;
}
}
/**
* Encrypt/Decrypt #(blocks) 64-bit blocks of text
* @param action [In] This parameter has no meaning for Dragon
* @param ctx [In/Out] Dragon context
* @param input [In] (plain/cipher)text blocks for (en/de)crypting
* @param output [Out] pre-allocated array for (cipher/plain)text blocks
* consisting of 8*(blocks) bytes
* @param blocks [In] number of blocks to (en/de)crypt
*/
void ECRYPT_process_blocks(
int action, /* 0 = encrypt; 1 = decrypt; */
ECRYPT_ctx* ctx,
const u8* input,
u8* output,
u32 blocks)
{
u32 *in = (u32*)input;
u32 *out = (u32*)output;
u32 a, b, c, d, e, f;
assert(ctx && input && output);
while (blocks > 0) {
DRAGON_ROUND(ctx, a, b, c, d, e, f)
*(out++) = U32TO32_BIG(a) ^ *(in++);
*(out++) = U32TO32_BIG(e) ^ *(in++);
blocks--;
}
}
/**
* Generate an arbitrary number of keystream bytes. Note this API
* is slower than block-wise encryption as Dragon is a 64-bit
* block-oriented cipher
*
* @param ctx [In/Out] Dragon context
* @param keystream [Out] pre-allocated array containing (msglen)
* bytes
* @param length [In] number of keystream bytes to produce
*/
void ECRYPT_keystream_bytes(
ECRYPT_ctx* ctx,
u8* keystream,
u32 length)
{
assert(ctx && keystream);
while ((length--) > 0) {
if (ctx->buffer_index == 0) {
ECRYPT_keystream_blocks(
ctx,
ctx->keystream_buffer,
DRAGON_BUFFER_SIZE);
}
*(keystream++) = ctx->keystream_buffer[ctx->buffer_index];
ctx->buffer_index = ((ctx->buffer_index + 1) % DRAGON_BUFFER_BYTES);
}
}
/**
* Encrypt an arbitrary number of bytes. Note this API is slower
* than block-wise encryption as Dragon is a 64-bit block-oriented
* cipher
*
* @param action [In] This parameter has no meaning for Dragon
* @param ctx [In/Out] Dragon context
* @param input [In] (plain)/(cipher)text for (en/de)crypting
* @param output [Out] (cipher)/(plain)text for (en/de)crypting
* @param msglen [In] number of bytes to (en/de)crypt
*/
void ECRYPT_process_bytes(
int action, /* 0 = encrypt; 1 = decrypt; */
ECRYPT_ctx* ctx,
const u8* input,
u8* output,
u32 msglen)
{
u32 len = msglen;
u32 i;
assert(ctx && input && output);
ECRYPT_keystream_bytes(ctx, output, len);
for (i = 0; i < msglen; i++) {
output[i] ^= input[i];
}
}
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