usbloadergx/source/libwbfs/rijndael.c

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/* Rijndael Block Cipher - rijndael.c
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Written by Mike Scott 21st April 1999
mike@compapp.dcu.ie
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Permission for free direct or derivative use is granted subject
to compliance with any conditions that the originators of the
algorithm place on its exploitation.
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*/
#include <stdio.h>
#include <string.h>
#define u8 unsigned char /* 8 bits */
#define u32 unsigned long /* 32 bits */
#define u64 unsigned long long
/* rotates x one bit to the left */
#define ROTL(x) (((x)>>7)|((x)<<1))
/* Rotates 32-bit word left by 1, 2 or 3 byte */
#define ROTL8(x) (((x)<<8)|((x)>>24))
#define ROTL16(x) (((x)<<16)|((x)>>16))
#define ROTL24(x) (((x)<<24)|((x)>>8))
/* Fixed Data */
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static u8 InCo[4] = { 0xB, 0xD, 0x9, 0xE }; /* Inverse Coefficients */
static u8 fbsub[256];
static u8 rbsub[256];
static u8 ptab[256], ltab[256];
static u32 ftable[256];
static u32 rtable[256];
static u32 rco[30];
/* Parameter-dependent data */
int Nk, Nb, Nr;
u8 fi[24], ri[24];
u32 fkey[120];
u32 rkey[120];
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static u32 pack(u8 *b)
{ /* pack bytes into a 32-bit Word */
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return ((u32 ) b[3] << 24) | ((u32 ) b[2] << 16) | ((u32 ) b[1] << 8) | (u32 ) b[0];
}
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static void unpack(u32 a, u8 *b)
{ /* unpack bytes from a word */
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b[0] = (u8 ) a;
b[1] = (u8 ) (a >> 8);
b[2] = (u8 ) (a >> 16);
b[3] = (u8 ) (a >> 24);
}
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static u8 xtime(u8 a)
{
u8 b;
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if (a & 0x80)
b = 0x1B;
else b = 0;
a <<= 1;
a ^= b;
return a;
}
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static u8 bmul(u8 x, u8 y)
{ /* x.y= AntiLog(Log(x) + Log(y)) */
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if (x && y)
return ptab[(ltab[x] + ltab[y]) % 255];
else return 0;
}
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static u32 SubByte(u32 a)
{
u8 b[4];
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unpack(a, b);
b[0] = fbsub[b[0]];
b[1] = fbsub[b[1]];
b[2] = fbsub[b[2]];
b[3] = fbsub[b[3]];
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return pack(b);
}
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static u8 product(u32 x, u32 y)
{ /* dot product of two 4-byte arrays */
u8 xb[4], yb[4];
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unpack(x, xb);
unpack(y, yb);
return bmul(xb[0], yb[0]) ^ bmul(xb[1], yb[1]) ^ bmul(xb[2], yb[2]) ^ bmul(xb[3], yb[3]);
}
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static u32 InvMixCol(u32 x)
{ /* matrix Multiplication */
u32 y, m;
u8 b[4];
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m = pack(InCo);
b[3] = product(m, x);
m = ROTL24( m );
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b[2] = product(m, x);
m = ROTL24( m );
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b[1] = product(m, x);
m = ROTL24( m );
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b[0] = product(m, x);
y = pack(b);
return y;
}
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u8 ByteSub(u8 x)
{
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u8 y = ptab[255 - ltab[x]]; /* multiplicative inverse */
x = y;
x = ROTL( x );
y ^= x;
x = ROTL( x );
y ^= x;
x = ROTL( x );
y ^= x;
x = ROTL( x );
y ^= x;
y ^= 0x63;
return y;
}
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void gentables(void)
{ /* generate tables */
int i;
u8 y, b[4];
/* use 3 as primitive root to generate power and log tables */
ltab[0] = 0;
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ptab[0] = 1;
ltab[1] = 0;
ptab[1] = 3;
ltab[3] = 1;
for (i = 2; i < 256; i++)
{
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ptab[i] = ptab[i - 1] ^ xtime(ptab[i - 1]);
ltab[ptab[i]] = i;
}
/* affine transformation:- each bit is xored with itself shifted one bit */
fbsub[0] = 0x63;
rbsub[0x63] = 0;
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for (i = 1; i < 256; i++)
{
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y = ByteSub((u8 ) i);
fbsub[i] = y;
rbsub[y] = i;
}
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for (i = 0, y = 1; i < 30; i++)
{
rco[i] = y;
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y = xtime(y);
}
/* calculate forward and reverse tables */
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for (i = 0; i < 256; i++)
{
y = fbsub[i];
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b[3] = y ^ xtime(y);
b[2] = y;
b[1] = y;
b[0] = xtime(y);
ftable[i] = pack(b);
y = rbsub[i];
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b[3] = bmul(InCo[0], y);
b[2] = bmul(InCo[1], y);
b[1] = bmul(InCo[2], y);
b[0] = bmul(InCo[3], y);
rtable[i] = pack(b);
}
}
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void gkey(int nb, int nk, char *key)
{ /* blocksize=32*nb bits. Key=32*nk bits */
/* currently nb,bk = 4, 6 or 8 */
/* key comes as 4*Nk bytes */
/* Key Scheduler. Create expanded encryption key */
int i, j, k, m, N;
int C1, C2, C3;
u32 CipherKey[8];
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Nb = nb;
Nk = nk;
/* Nr is number of rounds */
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if (Nb >= Nk)
Nr = 6 + Nb;
else Nr = 6 + Nk;
C1 = 1;
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if (Nb < 8)
{
C2 = 2;
C3 = 3;
}
else
{
C2 = 3;
C3 = 4;
}
/* pre-calculate forward and reverse increments */
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for (m = j = 0; j < nb; j++, m += 3)
{
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fi[m] = (j + C1) % nb;
fi[m + 1] = (j + C2) % nb;
fi[m + 2] = (j + C3) % nb;
ri[m] = (nb + j - C1) % nb;
ri[m + 1] = (nb + j - C2) % nb;
ri[m + 2] = (nb + j - C3) % nb;
}
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N = Nb * (Nr + 1);
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for (i = j = 0; i < Nk; i++, j += 4)
{
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CipherKey[i] = pack((u8 *) &key[j]);
}
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for (i = 0; i < Nk; i++)
fkey[i] = CipherKey[i];
for (j = Nk, k = 0; j < N; j += Nk, k++)
{
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fkey[j] = fkey[j - Nk] ^ SubByte(ROTL24( fkey[j-1] )) ^ rco[k];
if (Nk <= 6)
{
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for (i = 1; i < Nk && (i + j) < N; i++)
fkey[i + j] = fkey[i + j - Nk] ^ fkey[i + j - 1];
}
else
{
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for (i = 1; i < 4 && (i + j) < N; i++)
fkey[i + j] = fkey[i + j - Nk] ^ fkey[i + j - 1];
if ((j + 4) < N) fkey[j + 4] = fkey[j + 4 - Nk] ^ SubByte(fkey[j + 3]);
for (i = 5; i < Nk && (i + j) < N; i++)
fkey[i + j] = fkey[i + j - Nk] ^ fkey[i + j - 1];
}
}
/* now for the expanded decrypt key in reverse order */
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for (j = 0; j < Nb; j++)
rkey[j + N - Nb] = fkey[j];
for (i = Nb; i < N - Nb; i += Nb)
{
k = N - Nb - i;
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for (j = 0; j < Nb; j++)
rkey[k + j] = InvMixCol(fkey[i + j]);
}
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for (j = N - Nb; j < N; j++)
rkey[j - N + Nb] = fkey[j];
}
/* There is an obvious time/space trade-off possible here. *
* Instead of just one ftable[], I could have 4, the other *
* 3 pre-rotated to save the ROTL8, ROTL16 and ROTL24 overhead */
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void encrypt(char *buff)
{
int i, j, k, m;
u32 a[8], b[8], *x, *y, *t;
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for (i = j = 0; i < Nb; i++, j += 4)
{
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a[i] = pack((u8 *) &buff[j]);
a[i] ^= fkey[i];
}
k = Nb;
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x = a;
y = b;
/* State alternates between a and b */
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for (i = 1; i < Nr; i++)
{ /* Nr is number of rounds. May be odd. */
/* if Nb is fixed - unroll this next
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loop and hard-code in the values of fi[] */
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for (m = j = 0; j < Nb; j++, m += 3)
{ /* deal with each 32-bit element of the State */
/* This is the time-critical bit */
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y[j] = fkey[k++] ^ ftable[(u8 ) x[j]] ^ ROTL8( ftable[( u8 )( x[fi[m]] >> 8 )] )
^ ROTL16( ftable[( u8 )( x[fi[m+1]] >> 16 )] ) ^ ROTL24( ftable[x[fi[m+2]] >> 24] );
}
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t = x;
x = y;
y = t; /* swap pointers */
}
/* Last Round - unroll if possible */
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for (m = j = 0; j < Nb; j++, m += 3)
{
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y[j] = fkey[k++] ^ (u32 ) fbsub[(u8 ) x[j]] ^ ROTL8( ( u32 )fbsub[( u8 )( x[fi[m]] >> 8 )] )
^ ROTL16( ( u32 )fbsub[( u8 )( x[fi[m+1]] >> 16 )] ) ^ ROTL24( ( u32 )fbsub[x[fi[m+2]] >> 24] );
}
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for (i = j = 0; i < Nb; i++, j += 4)
{
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unpack(y[i], (u8 *) &buff[j]);
x[i] = y[i] = 0; /* clean up stack */
}
return;
}
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void decrypt(char *buff)
{
int i, j, k, m;
u32 a[8], b[8], *x, *y, *t;
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for (i = j = 0; i < Nb; i++, j += 4)
{
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a[i] = pack((u8 *) &buff[j]);
a[i] ^= rkey[i];
}
k = Nb;
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x = a;
y = b;
/* State alternates between a and b */
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for (i = 1; i < Nr; i++)
{ /* Nr is number of rounds. May be odd. */
/* if Nb is fixed - unroll this next
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loop and hard-code in the values of ri[] */
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for (m = j = 0; j < Nb; j++, m += 3)
{ /* This is the time-critical bit */
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y[j] = rkey[k++] ^ rtable[(u8 ) x[j]] ^ ROTL8( rtable[( u8 )( x[ri[m]] >> 8 )] )
^ ROTL16( rtable[( u8 )( x[ri[m+1]] >> 16 )] ) ^ ROTL24( rtable[x[ri[m+2]] >> 24] );
}
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t = x;
x = y;
y = t; /* swap pointers */
}
/* Last Round - unroll if possible */
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for (m = j = 0; j < Nb; j++, m += 3)
{
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y[j] = rkey[k++] ^ (u32 ) rbsub[(u8 ) x[j]] ^ ROTL8( ( u32 )rbsub[( u8 )( x[ri[m]] >> 8 )] )
^ ROTL16( ( u32 )rbsub[( u8 )( x[ri[m+1]] >> 16 )] ) ^ ROTL24( ( u32 )rbsub[x[ri[m+2]] >> 24] );
}
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for (i = j = 0; i < Nb; i++, j += 4)
{
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unpack(y[i], (u8 *) &buff[j]);
x[i] = y[i] = 0; /* clean up stack */
}
return;
}
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void aes_set_key(u8 *key)
{
gentables();
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gkey(4, 4, (char*) key);
}
// CBC mode decryption
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void aes_decrypt(u8 *iv, u8 *inbuf, u8 *outbuf, unsigned long long len)
{
u8 block[16];
unsigned int blockno = 0, i;
//printf("aes_decrypt(%p, %p, %p, %lld)\n", iv, inbuf, outbuf, len);
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for (blockno = 0; blockno <= (len / sizeof(block)); blockno++)
{
unsigned int fraction;
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if (blockno == (len / sizeof(block))) // last block
{
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fraction = len % sizeof(block);
if (fraction == 0) break;
memset(block, 0, sizeof(block));
}
else fraction = 16;
// debug_printf("block %d: fraction = %d\n", blockno, fraction);
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memcpy(block, inbuf + blockno * sizeof(block), fraction);
decrypt((char*) block);
u8 *ctext_ptr;
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if (blockno == 0)
ctext_ptr = iv;
else ctext_ptr = inbuf + (blockno - 1) * sizeof(block);
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for (i = 0; i < fraction; i++)
outbuf[blockno * sizeof(block) + i] = ctext_ptr[i] ^ block[i];
// debug_printf("Block %d output: ", blockno);
// hexdump(outbuf + blockno*sizeof(block), 16);
}
}
// CBC mode encryption
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void aes_encrypt(u8 *iv, u8 *inbuf, u8 *outbuf, unsigned long long len)
{
u8 block[16];
unsigned int blockno = 0, i;
// debug_printf("aes_decrypt(%p, %p, %p, %lld)\n", iv, inbuf, outbuf, len);
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for (blockno = 0; blockno <= (len / sizeof(block)); blockno++)
{
unsigned int fraction;
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if (blockno == (len / sizeof(block))) // last block
{
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fraction = len % sizeof(block);
if (fraction == 0) break;
memset(block, 0, sizeof(block));
}
else fraction = 16;
// debug_printf("block %d: fraction = %d\n", blockno, fraction);
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memcpy(block, inbuf + blockno * sizeof(block), fraction);
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for (i = 0; i < fraction; i++)
block[i] = inbuf[blockno * sizeof(block) + i] ^ iv[i];
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encrypt((char*) block);
memcpy(iv, block, sizeof(block));
memcpy(outbuf + blockno * sizeof(block), block, sizeof(block));
// debug_printf("Block %d output: ", blockno);
// hexdump(outbuf + blockno*sizeof(block), 16);
}
}