Powered by ViewCVS 1.0-dev
* imported original ECRYPT submissions after first automatic cleanup.
/* sfinks.c */
/*
* This is a reference implementation of the Stream cipher SFINKS,
* with authentication mechanism
*
* SFINKS is a HW-oriented stream cipher. This C implementation is only
* intended for simulation and is not optimized in any way.
*
* Author: Joseph Lano, "joe dot lano at gmail dot com"
*/
#include "ecrypt-sync-ae.h"
/* Two S-boxes, the first is only temporary, the second will contain the 16-bit inversion S-Box*/
u16 POWER[65536];
u16 INV[65536];
/*
* lfsr_clock
* This function clocks the LFSR linearly
* with a weight 17 primitive feedback polynomial
*/
void lfsr_clock(ECRYPT_AE_ctx* ctx)
{
u32 newbit;
u32 i;
newbit = ctx->LFSR[212]^ctx->LFSR[194]^ctx->LFSR[192]^ctx->LFSR[187]^
ctx->LFSR[163]^ctx->LFSR[151]^ctx->LFSR[125]^ctx->LFSR[115]^
ctx->LFSR[107]^ctx->LFSR[85]^ctx->LFSR[66]^ctx->LFSR[64]^
ctx->LFSR[52]^ctx->LFSR[48]^ctx->LFSR[14]^ctx->LFSR[0];
for (i=0;i<255;i++) ctx->LFSR[i]=ctx->LFSR[i+1];
ctx->LFSR[255]=newbit;
}
/*
* sbox_clock
* This function calculates the next output of the inversion function.
* It updates the virtual pipeline, corresponding to the actual
* pipeline in the hardware implementation
*/
void sbox_clock(ECRYPT_AE_ctx* ctx)
{
u32 i;
u16 input;
for (i=0;i<6;i++) ctx->pipe[i]=ctx->pipe[i+1];
for (i=0;i<6;i++) ctx->linmask[i]=ctx->linmask[i+1];
input=(ctx->LFSR[255]<<15)^(ctx->LFSR[244]<<14)^(ctx->LFSR[227]<<13)^(ctx->LFSR[193]<<12)^
(ctx->LFSR[161]<<11)^(ctx->LFSR[134]<<10)^(ctx->LFSR[105]<<9)^(ctx->LFSR[98]<<8)^
(ctx->LFSR[74]<<7)^(ctx->LFSR[58]<<6)^(ctx->LFSR[44]<<5)^(ctx->LFSR[21]<<4)^
(ctx->LFSR[19]<<3)^(ctx->LFSR[9]<<2)^(ctx->LFSR[6]<<1)^(ctx->LFSR[1]);
ctx->pipe[6]=INV[input];
ctx->linmask[6]=ctx->LFSR[0];
}
/*
* sr_clock
* shifts the SR one bit and inputs new bit
*/
void sr_clock(ECRYPT_AE_ctx* ctx)
{
ctx->SR[0]=(ctx->SR[0]<<1)^(ctx->SR[1]>>31);
ctx->SR[1]=(ctx->SR[1]<<1)^((ctx->pipe[0]>>1)&1);
}
/*
* GFexp
* Calculates POWER[i] that defines 2^i in the field GF(2^16), while using the
* corresponding primitive polynomial g(x)=X^16+X^5+X^3+X^2+1
*/
void GFexp()
{
u32 g = 0x1002D; /* The primitive polynomial X^16+X^5+X^3+X^2+1 */
const long n = (long)1 << 16;
u32 x = 1;
u32 i;
for (i =0;i<n-1;i++)
{
POWER[i] = x;
x <<= 1;
if (x & n) x ^= g;
}
POWER[n - 1] = 0;
}
/*
* GFpower
* Calculate sbox[i] that defines i^-1 in the field GF(2^16), while using the
* corresponding primitive polynomial g(x)=X^16+X^5+X^3+X^2+1
*/
void GFpower()
{
const long n = 1 << 16;
u32 i;
INV[0] = 0;
for (i=0;i<n-1;i++)
{
INV[(long)POWER[i]] = POWER[(n - 1 - i) % (n - 1)];
}
}
/*
* ECRYPT_init
* Initializes the (16,16) inversion S-box
*/
void ECRYPT_init()
{
GFexp();
GFpower();
}
/*
* ECRYPT_AE_keysetup
* copies the key into the state as an array of 80 bits
*/
void ECRYPT_AE_keysetup(
ECRYPT_AE_ctx* ctx,
const u8* key,
u32 keysize, /* Key size in bits. */
u32 ivsize, /* IV size in bits. */
u32 macsize) /* MAC size in bits. */
{
u32 i,j,counter;
u8 keybyte;
ctx->keysize=keysize;
ctx->ivsize=ivsize;
ctx->macsize=macsize;
counter=0;
for (i=0;i<10;i++)
{
keybyte=key[i];
for (j=0;j<8;j++)
{
ctx->key[counter]=keybyte&1;
counter++;
keybyte>>=1;
}
}
}
/*
* ECRYPT_AE_ivsetup
* - Put LFSR, pipeline, MAC and SR to zero
* - Put key and iv into LFSR
* - Perform 128 nonlinear resync clocks, initializing LFSR, pipe and SR
*/
void ECRYPT_AE_ivsetup(
ECRYPT_AE_ctx* ctx,
const u8* iv)
{
u32 i,j,counter;
u8 ivbyte;
u16 feedback;
counter=0;
/*set LFSR, pipelines, MAC and SR to zero*/
for (i=0;i<256;i++) ctx->LFSR[i]=0;
for (i=0;i<7;i++) ctx->pipe[i]=0;
for (i=0;i<7;i++) ctx->linmask[i]=0;
ctx->MAC[0]=0;
ctx->MAC[1]=0;
ctx->SR[0]=0;
ctx->SR[1]=0;
/* load key into LFSR*/
for (i=0;i<80;i++) ctx->LFSR[96+i]=ctx->key[i];
/* load iv into LFSR*/
for (i=0;i<10;i++)
{
ivbyte=iv[i];
for (j=0;j<8;j++)
{
ctx->LFSR[176+counter]=ivbyte&1;
counter++;
ivbyte>>=1;
}
}
/* set LFSR bit 95 to one */
ctx->LFSR[95]=1;
/*perform 128 nonlinear resync clocks*/
for (i=0;i<128;i++)
{
lfsr_clock(ctx);
feedback=ctx->pipe[0];
ctx->LFSR[80]^=(feedback&1);
feedback>>=1;
ctx->LFSR[17]^=(feedback&1);
feedback>>=1;
ctx->LFSR[66]^=(feedback&1);
feedback>>=1;
ctx->LFSR[179]^=(feedback&1);
feedback>>=1;
ctx->LFSR[52]^=(feedback&1);
feedback>>=1;
ctx->LFSR[213]^=(feedback&1);
feedback>>=1;
ctx->LFSR[118]^=(feedback&1);
feedback>>=1;
ctx->LFSR[247]^=(feedback&1);
feedback>>=1;
ctx->LFSR[232]^=(feedback&1);
feedback>>=1;
ctx->LFSR[41]^=(feedback&1);
feedback>>=1;
ctx->LFSR[154]^=(feedback&1);
feedback>>=1;
ctx->LFSR[11]^=(feedback&1);
feedback>>=1;
ctx->LFSR[204]^=(feedback&1);
feedback>>=1;
ctx->LFSR[173]^=(feedback&1);
feedback>>=1;
ctx->LFSR[142]^=(feedback&1);
feedback>>=1;
ctx->LFSR[111]^=(feedback&1);
ctx->MAC[0]^=ctx->SR[0];
ctx->MAC[1]^=ctx->SR[1];
sr_clock(ctx);
sbox_clock(ctx);
}
}
/*
* ECRYPT_AE_process_bytes
* Generate 'msglen' bytes of ciphertext from plaintext, or vice-versa
*/
void ECRYPT_AE_process_bytes(
int action, /* 0 = encrypt; 1 = decrypt; */
ECRYPT_AE_ctx* ctx,
const u8* input,
u8* output,
u32 msglen) /* Message length in bytes. */
{
u32 i,j;
u8 keystreambyte;
u8 inputbyte;
for (i=0;i<msglen;i++)
{
keystreambyte=0;
inputbyte=input[i];
for (j=0;j<8;j++)
{
lfsr_clock(ctx);
sbox_clock(ctx);
keystreambyte=(keystreambyte<<1)^(ctx->pipe[0]&1)^ctx->linmask[0];
if (!action)
{
if ((inputbyte>>(7-j))&1)
{
ctx->MAC[0]^=ctx->SR[0];
ctx->MAC[1]^=ctx->SR[1];
}
}
else
{
if ((keystreambyte^(inputbyte>>(7-j)))&1)
{
ctx->MAC[0]^=ctx->SR[0];
ctx->MAC[1]^=ctx->SR[1];
}
}
sr_clock(ctx);
}
output[i]=input[i]^keystreambyte;
}
}
void ECRYPT_AE_finalize(
ECRYPT_AE_ctx* ctx,
u8* mac)
{
int i;
for (i=0;i<8;i++) mac[i]=(ctx->MAC[i/4])>>(8*((7-i)%4)) & 0xFF;
ECRYPT_AE_process_bytes(0,ctx,mac,mac,8);
}
void ECRYPT_AE_authenticate_bytes(
ECRYPT_AE_ctx* ctx,
const u8* aad,
u32 aadlen) /* Length of associated data in bytes. */
{
u32 i,j;
u8 aadbyte;
for (i=0;i<aadlen;i++)
{
aadbyte=aad[i];
for (j=0;j<8;j++)
{
lfsr_clock(ctx);
sbox_clock(ctx);
if ((aadbyte>>(7-j))&1)
{
ctx->MAC[0]^=ctx->SR[0];
ctx->MAC[1]^=ctx->SR[1];
}
sr_clock(ctx);
}
}
}
|
eSTREAM Project Powered by ViewCVS 1.0-dev |
ViewCVS and CVS Help |