/* rc6 (TM) * Unoptimized sample implementation of Ron Rivest's submission to the * AES bakeoff. * * Salvo Salasio, 19 June 1998 * * Intellectual property notes:  The name of the algorithm (RC6) is * trademarked; any property rights to the algorithm or the trademark * should be discussed with discussed with the authors of the defining * paper "The RC6(TM) Block Cipher": Ronald L. Rivest (MIT), * M.J.B. Robshaw (RSA Labs), R. Sidney (RSA Labs), and Y.L. Yin (RSA Labs), * distributed 18 June 1998 and available from the lead author's web site. * * This sample implementation is placed in the public domain by the author, * Salvo Salasio.  The ROTL and ROTR definitions were cribbed from RSA Labs' * RC5 reference implementation. */#include <stdio.h>/* RC6 is parameterized for w-bit words, b bytes of key, and * r rounds.  The AES version of RC6 specifies b=16, 24, or 32; * w=32; and r=20. */  #define w 32	/* word size in bits */#define r 20	/* based on security estimates */#define P32 0xB7E15163	/* Magic constants for key setup */#define Q32 0x9E3779B9/* derived constants */#define bytes   (w / 8)				/* bytes per word */#define c       ((b + bytes - 1) / bytes)	/* key in words, rounded up */#define R24     (2 * r + 4)#define lgw     5                       	/* log2(w) -- wussed out *//* Rotations */#define ROTL(x,y) (((x)<<(y&(w-1))) | ((x)>>(w-(y&(w-1)))))#define ROTR(x,y) (((x)>>(y&(w-1))) | ((x)<<(w-(y&(w-1)))))unsigned int S[R24 - 1];		/* Key schedule */void rc6_key_setup(unsigned char *K, int b){	int i, j, s, v;	unsigned int L[(32 + bytes - 1) / bytes]; /* Big enough for max b */	unsigned int A, B;	L[c - 1] = 0;	for (i = b - 1; i >= 0; i--)		L[i / bytes] = (L[i / bytes] << 8) + K[i];	S[0] = P32;	for (i = 1; i <= 2 * r + 3; i++)		S[i] = S[i - 1] + Q32;	A = B = i = j = 0;	v = R24;	if (c > v) v = c;	v *= 3;	for (s = 1; s <= v; s++)	{		A = S[i] = ROTL(S[i] + A + B, 3);		B = L[j] = ROTL(L[j] + A + B, A + B);		i = (i + 1) % R24;		j = (j + 1) % c;	}}void rc6_block_encrypt(unsigned int *pt, unsigned int *ct){	unsigned int A, B, C, D, t, u, x;	int i, j;	A = pt[0];	B = pt[1];	C = pt[2];	D = pt[3];	B += S[0];	D += S[1];	for (i = 2; i <= 2 * r; i += 2)	{		t = ROTL(B * (2 * B + 1), lgw);		u = ROTL(D * (2 * D + 1), lgw);		A = ROTL(A ^ t, u) + S[i];		C = ROTL(C ^ u, t) + S[i + 1];		x = A;		A = B;		B = C;		C = D;		D = x;	}	A += S[2 * r + 2];	C += S[2 * r + 3];	ct[0] = A;	ct[1] = B;	ct[2] = C;	ct[3] = D;}void rc6_block_decrypt(unsigned int *ct, unsigned int *pt){	unsigned int A, B, C, D, t, u, x;	int i, j;	A = ct[0];	B = ct[1];	C = ct[2];	D = ct[3];	C -= S[2 * r + 3];	A -= S[2 * r + 2];	for (i = 2 * r; i >= 2; i -= 2)	{		x = D;		D = C;		C = B;		B = A;		A = x;		u = ROTL(D * (2 * D + 1), lgw);		t = ROTL(B * (2 * B + 1), lgw);		C = ROTR(C - S[i + 1], t) ^ u;		A = ROTR(A - S[i], u) ^ t;	}	D -= S[1];	B -= S[0];	pt[0] = A;	pt[1] = B;	pt[2] = C;	pt[3] = D;	}struct test_struct{	int keylen;	unsigned char key[32];	unsigned int pt[4];	unsigned int ct[4];} tests[] ={	{ 16,   {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},		{0x00000000, 0x00000000, 0x00000000, 0x00000000},		{0x36a5c38f, 0x78f7b156, 0x4edf29c1, 0x1ea44898},	},	{ 16,   {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,		 0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78},		{0x35241302, 0x79685746, 0xbdac9b8a, 0xf1e0dfce},		{0x2f194e52, 0x23c61547, 0x36f6511f, 0x183fa47e},	},	{ 24,   {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},		{0x00000000, 0x00000000, 0x00000000, 0x00000000},		{0xcb1bd66c, 0x38300b19, 0x163f8a4e, 0x82ae9086},	},	{ 24,   {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,		 0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,		 0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0},		{0x35241302, 0x79685746, 0xbdac9b8a, 0xf1e0dfce},		{0xd0298368, 0x0405e519, 0x2ae9521e, 0xd49152f9},	},	{ 32,   {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,		 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},		{0x00000000, 0x00000000, 0x00000000, 0x00000000},		{0x05bd5f8f, 0xa85fd110, 0xda3ffa93, 0xc27e856e},	},	{ 32,   {0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,		 0x01, 0x12, 0x23, 0x34, 0x45, 0x56, 0x67, 0x78,		 0x89, 0x9a, 0xab, 0xbc, 0xcd, 0xde, 0xef, 0xf0,		 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe},		{0x35241302, 0x79685746, 0xbdac9b8a, 0xf1e0dfce},		{0x161824c8, 0x89e4d7f0, 0xa116ad20, 0x485d4e67},	},	{       0,	}};intmain(){	unsigned int ct[4], pt[4];	int i;	struct test_struct *p;	for (p = tests, i = 1; p->keylen; p++, i++)	{		rc6_key_setup(p->key, p->keylen);		rc6_block_encrypt(p->pt, ct);		printf("Test   %d:  %08x %08x %08x %08x\n",			i, ct[0], ct[1], ct[2], ct[3]);		printf("Should be: %08x %08x %08x %08x\n",			p->ct[0], p->ct[1], p->ct[2], p->ct[3]);		rc6_block_decrypt(ct, pt);		printf("Plain:     %08x %08x %08x %08x\n",			pt[0], pt[1], pt[2], pt[3]);		printf("Should be: %08x %08x %08x %08x\n\n",			p->pt[0], p->pt[1], p->pt[2], p->pt[3]);	}	return 0;}