aes.c

This is an implentation of the RIJNDAEL cryptosystem.

/* This is an implentation of the RIJNDAEL cryptosystem.
 * for 128 bit plaintext block.
 * This programme only gives the instance of 128 bit key.
 * You can modify a little details to meet you need for 192
 * or 256 bit key input
 */

#include <stdio.h>
#include <time.h>

typedef	unsigned char	u1byte;		/* an 8 bit unsigned character type */
typedef	unsigned long	u4byte;		/* a 32 bit unsigned integer type */

#define LARGE_TABLES

u1byte	pow_tab[256];
u1byte	log_tab[256];
u1byte	sbx_tab[256];
u1byte	isb_tab[256];
u4byte	rco_tab[10];
u4byte	ft_tab[4][256];
u4byte	it_tab[4][256];

#ifdef	LARGE_TABLES
u4byte	fl_tab[4][256];
u4byte	il_tab[4][256];
#endif

u4byte	tab_gen = 0;

u4byte	k_len;
u4byte	e_key[64];			/* e_key[60]; */
u4byte	d_key[64];			/* d_key[60]; */

#define	ff_mult(a, b)	(a && b ? pow_tab[(log_tab[a] + log_tab[b]) % 255] : 0)

#define	byte(x, n)	((u1byte)((x) >> (8 * n)))

#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)

#define	rotr(x, n)	(((x) >> ((int)(n))) | ((x) << (32 - (int)(n))))
#define	rotl(x, n)	(((x) << ((int)(n))) | ((x) >> (32 - (int)(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)				\
	( ((u4byte)sbx_tab[byte(x, 0)] << 0) ^	\
	((u4byte)sbx_tab[byte(x, 1)] << 8) ^	\
	((u4byte)sbx_tab[byte(x, 2)] << 16) ^	\
	((u4byte)sbx_tab[byte(x, 3)] << 24) )

#define	f_rl(bo, bi, n, k)						\
	bo[n] = (u4byte)sbx_tab[byte(bi[n], 0)] ^			\
		rotl(((u4byte)sbx_tab[byte(bi[(n + 1) & 3], 1)]), 8) ^	\
		rotl(((u4byte)sbx_tab[byte(bi[(n + 2) & 3], 2)]), 16) ^	\
		rotl(((u4byte)sbx_tab[byte(bi[(n + 3) & 3], 3)]), 24) ^	*(k + n)

#define	i_rl(bo, bi, n, k)						\
	bo[n] = (u4byte)isb_tab[byte(bi[n], 0)] ^			\
		rotl(((u4byte)isb_tab[byte(bi[(n + 3) & 3], 1)]), 8) ^	\
		rotl(((u4byte)isb_tab[byte(bi[(n + 2) & 3], 2)]), 16) ^	\
		rotl(((u4byte)isb_tab[byte(bi[(n + 1) & 3], 3)]), 24) ^	*(k + n)

#endif


void	gen_tabs(void);
void	set_key(const u4byte in_key[], const u4byte key_len);
void	encrypt(const u4byte in_blk[4], u4byte out_blk[4]);
void	decrypt(const u4byte in_blk[4], u4byte out_blk[4]);


void	gen_tabs(void)
{
	u4byte	i, t;
	u1byte	p, q;

	/* log and power table for GF(2**8) finite field with	*/
	/* 0x11b as modular polynomial - the simplest primitive	*/
	/* root is 0x11b, used here to generate the tables	*/

	for(i=0, p=1; i<256; ++i)
	{
		pow_tab[i] = (u1byte)p;
		log_tab[p] = (u1byte)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 form 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] = (u1byte)p; isb_tab[p] = (u1byte)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 = ((u4byte)ff_mult(2, p)) |
			((u4byte)p << 8) |
			((u4byte)p << 16) |
			((u4byte)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 = ((u4byte)ff_mult(14, p)) |
			((u4byte)ff_mult(9, p) << 8) |
			((u4byte)ff_mult(13, p) << 16) |
			((u4byte)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);;
	}

	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)

/* initialize 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;	\
}

void	set_key(const u4byte in_key[], const u4byte key_len)
{
	u4byte	i, t, u, v, w;

	if(!tab_gen)
		gen_tabs();

	k_len = (key_len + 31) / 32;

	e_key[0] = in_key[0];
	e_key[1] = in_key[1];
	e_key[2] = in_key[2];
	e_key[3] = in_key[3];

	switch(k_len)
	{
		case 4:
			t = e_key[3];
			for(i=0; i<10; ++i)
				loop4(i);
			break;

		case 6:
			e_key[4] = in_key[4];
			t = e_key[5] = in_key[5];
			for(i=0; i<8; ++i)
				loop6(i);
			break;

		case 8:
			e_key[4] = in_key[4];
			e_key[5] = in_key[5];
			e_key[6] = in_key[6];
			t = e_key[7] = in_key[7];
			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]);
	}
}

/* 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);	\
	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)

void	encrypt(const u4byte in_blk[4], u4byte out_blk[4])
{
	u4byte	b0[4], b1[4], *kp;

	b0[0] = in_blk[0] ^ e_key[0];
	b0[1] = in_blk[1] ^ e_key[1];
	b0[2] = in_blk[2] ^ e_key[2];
	b0[3] = in_blk[3] ^ e_key[3];

	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] = b0[0]; out_blk[1] = b0[1];
	out_blk[2] = b0[2]; out_blk[3] = 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	decrypt(const u4byte in_blk[4], u4byte out_blk[4])
{
	u4byte	b0[4], b1[4], *kp;

	b0[0] = in_blk[0] ^ e_key[4* k_len + 24];
	b0[1] = in_blk[1] ^ e_key[4* k_len + 25];
	b0[2] = in_blk[2] ^ e_key[4* k_len + 26];
	b0[3] = 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] = b0[0]; out_blk[1] = b0[1];
	out_blk[2] = b0[2]; out_blk[3] = b0[3];
}

/* use data to test programme */

void main()
{
	int		i;
	u4byte		out_block[4];
	//const u4byte	in_key[4] ={0x11111111, 0x22222222, 0x33333333, 0x44444444};
	//const u4byte	plain_block[4] ={0x12121212, 0x34343434, 0x45454545, 0x56565656};
	//const u4byte	cipher_block[4] ={0x844050f7, 0xe346a4ff, 0x375104da, 0xabb97f8b};

	//const u4byte	in_key[8] ={0x11111111, 0x22222222, 0x33333333, 0x44444444,
	//				0x55555555, 0x66666666, 0x77777777, 0x88888888};
	//const u4byte	plain_block[8] ={0x12121212, 0x34343434, 0x45454545, 0x56565656,
	//				0x67676767, 0x78787878, 0x89898989, 0x9a9a9a9a};
	//const u4byte	cipher_block[8] ={0x844050f7, 0xe346a4ff, 0x375104da, 0xabb97f8b,
	//				0x844050f7, 0xe346a4ff, 0x375104da, 0xabb97f8b};

	const u4byte	in_key[4] ={0x2b7e1516, 0x28aed2a6, 0xabf71588, 0x09cf4f3c};
	const u4byte	plain_block[4] ={0x3243f6a8, 0x885a308d, 0x313198a2, 0xe0370734};
	const u4byte	cipher_block[4] ={0x3925841d, 0x02dc09fb, 0xdc118597, 0x196a0b32};

	time_t	t;
	long	j;

	printf("\n----------------------------------------------\n");
	printf("in_key:\n");
	for(i=0; i<4; i++)
		printf("%8lx ", in_key[i]);

	printf("\nplain_block:\n");
	for(i=0; i<4; i++)
		printf("%8lx ", plain_block[i]);

	printf("\ncipher_block:\n");
	for(i=0; i<4; i++)
		printf("%8lx ", cipher_block[i]);


	set_key(in_key, 256);

	t = time(NULL);
	printf("\nThe number of seconds since January 1, 1970 is %ld\n",t);
	printf("\nEncryptions/Decryptions: 1 ~ 500000 times\n");

	for(j=0; j<500000l; j++)
	{
	encrypt(plain_block, out_block);
	//printf("\nEncryptions:\n");
	//for(i=0; i<4; i++)
	//	printf("%8lx ", out_block[i]);

	//decrypt(cipher_block, out_block);
	decrypt(out_block, out_block);
	//printf("\nDecryptions:\n");
	//for(i=0; i<4; i++)
	//	printf("%8lx ", out_block[i]);
	}

	t = time(NULL);
	printf("\nThe number of seconds since January 1, 1970 is %ld\n",t);

	//return(0);
}