📄 aes.cpp
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/* This is an independent implementation of the encryption algorithm: */
/* */
/* RIJNDAEL by Joan Daemen and Vincent Rijmen */
/* */
/* which is a candidate algorithm in the Advanced Encryption Standard */
/* programme of the US National Institute of Standards and Technology. */
/* */
/* Copyright in this implementation is held by Dr B R Gladman but I */
/* hereby give permission for its free direct or derivative use subject */
/* to acknowledgment of its origin and compliance with any conditions */
/* that the originators of the algorithm place on its exploitation. */
/* */
/* Dr Brian Gladman (gladman@seven77.demon.co.uk) 14th January 1999 */
#include "aes_defs.h"
/*------------------ DLW debug code */
#if _VERBOSE_
#include <stdio.h>
int rNum;
void ShowBlk(const u32b *b,int final)
{
int i,j;
u32b x;
u08b a;
printf("%s %2d: ",(final) ? "Final" : "Round",rNum++);
for (i=0;i<4;i++)
{
printf(" ");
x = b[i]; /* always used internally as "little-endian" */
for (j=0;j<4;j++)
{
a = byte(x,j);
printf(" %02X",a);
}
}
printf("\n");
}
void ShowKeySched(const u32b *key,int cnt,const char *hdrMsg)
{
int i,j;
u32b x;
u08b a;
printf("%s\n",hdrMsg);
for (i=0;i<4*cnt;i++)
{
x = key[i]; /* key always used as "little-endian" */
printf(" ");
for (j=0;j<4;j++)
{
a = byte(x,j);
printf(" %02X",a);
}
if ((i%4) == 3) printf("\n");
}
}
#define SetR(r) { rNum = r; }
#else
#define ShowBlk(b,f)
#define SetR(r)
#define ShowKeySched(key,cnt,hdrMsg)
#endif
/*---------------- end of DLW debug */
#define LARGE_TABLES
u08b pow_tab[256];
u08b log_tab[256];
u08b sbx_tab[256];
u08b isb_tab[256];
u32b rco_tab[ 10];
u32b ft_tab[4][256];
u32b it_tab[4][256];
#ifdef LARGE_TABLES
u32b fl_tab[4][256];
u32b il_tab[4][256];
#endif
u32b tab_gen = 0;
u32b k_len;
u32b e_key[60];
u32b d_key[60];
#define ff_mult(a,b) (a && b ? pow_tab[(log_tab[a] + log_tab[b]) % 255] : 0)
#define f_rn(bo, bi, n, k) \
bo[n] = ft_tab[0][byte(bi[n],0)] ^ \
ft_tab[1][byte(bi[(n + 1) & 3],1)] ^ \
ft_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
#define i_rn(bo, bi, n, k) \
bo[n] = it_tab[0][byte(bi[n],0)] ^ \
it_tab[1][byte(bi[(n + 3) & 3],1)] ^ \
it_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
#ifdef LARGE_TABLES
#define ls_box(x) \
( fl_tab[0][byte(x, 0)] ^ \
fl_tab[1][byte(x, 1)] ^ \
fl_tab[2][byte(x, 2)] ^ \
fl_tab[3][byte(x, 3)] )
#define f_rl(bo, bi, n, k) \
bo[n] = fl_tab[0][byte(bi[n],0)] ^ \
fl_tab[1][byte(bi[(n + 1) & 3],1)] ^ \
fl_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
#define i_rl(bo, bi, n, k) \
bo[n] = il_tab[0][byte(bi[n],0)] ^ \
il_tab[1][byte(bi[(n + 3) & 3],1)] ^ \
il_tab[2][byte(bi[(n + 2) & 3],2)] ^ \
il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
#else
#define ls_box(x) \
((u32b)sbx_tab[byte(x, 0)] << 0) ^ \
((u32b)sbx_tab[byte(x, 1)] << 8) ^ \
((u32b)sbx_tab[byte(x, 2)] << 16) ^ \
((u32b)sbx_tab[byte(x, 3)] << 24)
#define f_rl(bo, bi, n, k) \
bo[n] = (u32b)sbx_tab[byte(bi[n],0)] ^ \
rotl(((u32b)sbx_tab[byte(bi[(n + 1) & 3],1)]), 8) ^ \
rotl(((u32b)sbx_tab[byte(bi[(n + 2) & 3],2)]), 16) ^ \
rotl(((u32b)sbx_tab[byte(bi[(n + 3) & 3],3)]), 24) ^ *(k + n)
#define i_rl(bo, bi, n, k) \
bo[n] = (u32b)isb_tab[byte(bi[n],0)] ^ \
rotl(((u32b)isb_tab[byte(bi[(n + 3) & 3],1)]), 8) ^ \
rotl(((u32b)isb_tab[byte(bi[(n + 2) & 3],2)]), 16) ^ \
rotl(((u32b)isb_tab[byte(bi[(n + 1) & 3],3)]), 24) ^ *(k + n)
#endif
void gen_tabs(void)
{ u32b i, t;
u08b p, q;
/* log and power tables for GF(2**8) finite field with */
/* 0x11b as modular polynomial - the simplest prmitive */
/* root is 0x11, used here to generate the tables */
for(i = 0,p = 1; i < 256; ++i)
{
pow_tab[i] = (u08b)p; log_tab[p] = (u08b)i;
p = p ^ (p << 1) ^ (p & 0x80 ? 0x01b : 0);
}
log_tab[1] = 0; p = 1;
for(i = 0; i < 10; ++i)
{
rco_tab[i] = p;
p = (p << 1) ^ (p & 0x80 ? 0x1b : 0);
}
/* note that the affine byte transformation matrix in */
/* rijndael specification is in big endian format with */
/* bit 0 as the most significant bit. In the remainder */
/* of the specification the bits are numbered from the */
/* least significant end of a byte. */
for(i = 0; i < 256; ++i)
{
p = (i ? pow_tab[255 - log_tab[i]] : 0); q = p;
q = (q >> 7) | (q << 1); p ^= q;
q = (q >> 7) | (q << 1); p ^= q;
q = (q >> 7) | (q << 1); p ^= q;
q = (q >> 7) | (q << 1); p ^= q ^ 0x63;
sbx_tab[i] = (u08b)p; isb_tab[p] = (u08b)i;
}
for(i = 0; i < 256; ++i)
{
p = sbx_tab[i];
#ifdef LARGE_TABLES
t = p; fl_tab[0][i] = t;
fl_tab[1][i] = rotl(t, 8);
fl_tab[2][i] = rotl(t, 16);
fl_tab[3][i] = rotl(t, 24);
#endif
t = ((u32b)ff_mult(2, p)) |
((u32b)p << 8) |
((u32b)p << 16) |
((u32b)ff_mult(3, p) << 24);
ft_tab[0][i] = t;
ft_tab[1][i] = rotl(t, 8);
ft_tab[2][i] = rotl(t, 16);
ft_tab[3][i] = rotl(t, 24);
p = isb_tab[i];
#ifdef LARGE_TABLES
t = p; il_tab[0][i] = t;
il_tab[1][i] = rotl(t, 8);
il_tab[2][i] = rotl(t, 16);
il_tab[3][i] = rotl(t, 24);
#endif
t = ((u32b)ff_mult(14, p)) |
((u32b)ff_mult( 9, p) << 8) |
((u32b)ff_mult(13, p) << 16) |
((u32b)ff_mult(11, p) << 24);
it_tab[0][i] = t;
it_tab[1][i] = rotl(t, 8);
it_tab[2][i] = rotl(t, 16);
it_tab[3][i] = rotl(t, 24);
#if _VERBOSE_
if (i<4) /* helpful for debugging on new platform */
{ /* (compare with results from known platform) */
if (i==0)
printf("%8s : %08X %08X %08X %08X\n","rco_tab",
rco_tab[0],rco_tab[1],rco_tab[2],rco_tab[3]);
#define _ShowTab(tName) printf("%8s[%d]: %08X %08X %08X %08X\n",#tName,i, \
tName[0][i],tName[1][i],tName[2][i],tName[3][i]);
_ShowTab(it_tab);
_ShowTab(ft_tab);
#ifdef LARGE_TABLES
_ShowTab(il_tab);
_ShowTab(fl_tab);
#endif
}
#endif
}
tab_gen = 1;
};
#define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
#define imix_col(y,x) \
u = star_x(x); \
v = star_x(u); \
w = star_x(v); \
t = w ^ (x); \
(y) = u ^ v ^ w; \
(y) ^= rotr(u ^ t, 8) ^ \
rotr(v ^ t, 16) ^ \
rotr(t,24)
/* initialise the key schedule from the user supplied key */
#define loop4(i) \
{ t = ls_box(rotr(t, 8)) ^ rco_tab[i]; \
t ^= e_key[4 * i]; e_key[4 * i + 4] = t; \
t ^= e_key[4 * i + 1]; e_key[4 * i + 5] = t; \
t ^= e_key[4 * i + 2]; e_key[4 * i + 6] = t; \
t ^= e_key[4 * i + 3]; e_key[4 * i + 7] = t; \
}
#define loop6(i) \
{ t = ls_box(rotr(t, 8)) ^ rco_tab[i]; \
t ^= e_key[6 * i]; e_key[6 * i + 6] = t; \
t ^= e_key[6 * i + 1]; e_key[6 * i + 7] = t; \
t ^= e_key[6 * i + 2]; e_key[6 * i + 8] = t; \
t ^= e_key[6 * i + 3]; e_key[6 * i + 9] = t; \
t ^= e_key[6 * i + 4]; e_key[6 * i + 10] = t; \
t ^= e_key[6 * i + 5]; e_key[6 * i + 11] = t; \
}
#define loop8(i) \
{ t = ls_box(rotr(t, 8)) ^ rco_tab[i]; \
t ^= e_key[8 * i]; e_key[8 * i + 8] = t; \
t ^= e_key[8 * i + 1]; e_key[8 * i + 9] = t; \
t ^= e_key[8 * i + 2]; e_key[8 * i + 10] = t; \
t ^= e_key[8 * i + 3]; e_key[8 * i + 11] = t; \
t = e_key[8 * i + 4] ^ ls_box(t); \
e_key[8 * i + 12] = t; \
t ^= e_key[8 * i + 5]; e_key[8 * i + 13] = t; \
t ^= e_key[8 * i + 6]; e_key[8 * i + 14] = t; \
t ^= e_key[8 * i + 7]; e_key[8 * i + 15] = t; \
}
u32b *AES_SetKey(const u32b in_key[], const u32b key_len)
{ u32b i, t, u, v, w;
if(!tab_gen)
gen_tabs();
k_len = (key_len + 31) / 32;
for (i=0;i<k_len;i++)
e_key[i] = bswap(in_key[i]);
t = e_key[k_len-1];
switch(k_len)
{
case 4: for(i = 0; i < 10; ++i)
loop4(i);
break;
case 6: for(i = 0; i < 8; ++i)
loop6(i);
break;
case 8: for(i = 0; i < 7; ++i)
loop8(i);
break;
}
d_key[0] = e_key[0]; d_key[1] = e_key[1];
d_key[2] = e_key[2]; d_key[3] = e_key[3];
for(i = 4; i < 4 * k_len + 24; ++i)
{
imix_col(d_key[i], e_key[i]);
}
ShowKeySched(e_key,4,"Encryption key schedule:");
ShowKeySched(d_key,4,"Decryption key schedule:");
return e_key;
};
/* encrypt a block of text */
#define f_nround(bo, bi, k) \
f_rn(bo, bi, 0, k); \
f_rn(bo, bi, 1, k); \
f_rn(bo, bi, 2, k); \
f_rn(bo, bi, 3, k); \
ShowBlk(bo,0); \
k += 4
#define f_lround(bo, bi, k) \
f_rl(bo, bi, 0, k); \
f_rl(bo, bi, 1, k); \
f_rl(bo, bi, 2, k); \
f_rl(bo, bi, 3, k); \
ShowBlk(bo,1);
void AES_Encrypt(const u32b in_blk[4], u32b out_blk[4])
{ u32b b0[4], b1[4], *kp;
b0[0] = bswap(in_blk[0]) ^ e_key[0];
b0[1] = bswap(in_blk[1]) ^ e_key[1];
b0[2] = bswap(in_blk[2]) ^ e_key[2];
b0[3] = bswap(in_blk[3]) ^ e_key[3];
SetR(1); ShowBlk(b0,0);
kp = e_key + 4;
if(k_len > 6)
{
f_nround(b1, b0, kp); f_nround(b0, b1, kp);
}
if(k_len > 4)
{
f_nround(b1, b0, kp); f_nround(b0, b1, kp);
}
f_nround(b1, b0, kp); f_nround(b0, b1, kp);
f_nround(b1, b0, kp); f_nround(b0, b1, kp);
f_nround(b1, b0, kp); f_nround(b0, b1, kp);
f_nround(b1, b0, kp); f_nround(b0, b1, kp);
f_nround(b1, b0, kp); f_lround(b0, b1, kp);
out_blk[0] = bswap(b0[0]);
out_blk[1] = bswap(b0[1]);
out_blk[2] = bswap(b0[2]);
out_blk[3] = bswap(b0[3]);
};
/* decrypt a block of text */
#define i_nround(bo, bi, k) \
i_rn(bo, bi, 0, k); \
i_rn(bo, bi, 1, k); \
i_rn(bo, bi, 2, k); \
i_rn(bo, bi, 3, k); \
k -= 4
#define i_lround(bo, bi, k) \
i_rl(bo, bi, 0, k); \
i_rl(bo, bi, 1, k); \
i_rl(bo, bi, 2, k); \
i_rl(bo, bi, 3, k)
void AES_Decrypt(const u32b in_blk[4], u32b out_blk[4])
{ u32b b0[4], b1[4], *kp;
b0[0] = bswap(in_blk[0]) ^ e_key[4 * k_len + 24];
b0[1] = bswap(in_blk[1]) ^ e_key[4 * k_len + 25];
b0[2] = bswap(in_blk[2]) ^ e_key[4 * k_len + 26];
b0[3] = bswap(in_blk[3]) ^ e_key[4 * k_len + 27];
kp = d_key + 4 * (k_len + 5);
if(k_len > 6)
{
i_nround(b1, b0, kp); i_nround(b0, b1, kp);
}
if(k_len > 4)
{
i_nround(b1, b0, kp); i_nround(b0, b1, kp);
}
i_nround(b1, b0, kp); i_nround(b0, b1, kp);
i_nround(b1, b0, kp); i_nround(b0, b1, kp);
i_nround(b1, b0, kp); i_nround(b0, b1, kp);
i_nround(b1, b0, kp); i_nround(b0, b1, kp);
i_nround(b1, b0, kp); i_lround(b0, b1, kp);
out_blk[0] = bswap(b0[0]);
out_blk[1] = bswap(b0[1]);
out_blk[2] = bswap(b0[2]);
out_blk[3] = bswap(b0[3]);
};
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