aes.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

/*
 * this code is derived from the following source,
 * and modified to fit into the plan 9 libsec interface.
 * most of the changes are confined to the top section,
 * with the exception of converting Te4 and Td4 into u8 rather than u32 arrays.
 *
 * rijndael-alg-fst.c
 *
 * @version 3.0 (December 2000)
 *
 * Optimised ANSI C code for the Rijndael cipher (now AES)
 *
 * @author Vincent Rijmen <[e-mail]>
 * @author Antoon Bosselaers <[e-mail]>
 * @author Paulo Barreto <[e-mail]>
 *
 * This code is hereby placed in the public domain.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ''AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <u.h>
#include <libc.h>
#include <libsec.h>

typedef uchar	u8;
typedef u32int	u32;
#define FULL_UNROLL

static const u32 Td0[256];
static const u32 Td1[256];
static const u32 Td2[256];
static const u32 Td3[256];
static const u8  Te4[256];

static int rijndaelKeySetupEnc(u32 rk[/*4*(Nr + 1)*/], const u8 cipherKey[], int keyBits);
static int rijndaelKeySetupDec(u32 rk[/*4*(Nr + 1)*/], const u8 cipherKey[], int keyBits);
static int rijndaelKeySetup(u32 erk[/*4*(Nr + 1)*/], u32 drk[/*4*(Nr + 1)*/], const u8 cipherKey[], int keyBits);
static void	rijndaelEncrypt(const u32int rk[], int Nr, const uchar pt[16], uchar ct[16]);
static void	rijndaelDecrypt(const u32int rk[], int Nr, const uchar ct[16], uchar pt[16]);

void
setupAESstate(AESstate *s, uchar key[], int keybytes, uchar *ivec)
{
	memset(s, 0, sizeof(*s));
	if(keybytes > AESmaxkey)
		keybytes = AESmaxkey;
	memmove(s->key, key, keybytes);
	s->keybytes = keybytes;
	s->rounds = rijndaelKeySetup(s->ekey, s->dkey, s->key, keybytes * 8);
	if(ivec != nil)
		memmove(s->ivec, ivec, AESbsize);
	if(keybytes==16 || keybytes==24 || keybytes==32)
		s->setup = 0xcafebabe;
	// else rijndaelKeySetup was invalid
}

// Define by analogy with desCBCencrypt;  AES modes are not standardized yet.
// Because of the way that non-multiple-of-16 buffers are handled,
// the decryptor must be fed buffers of the same size as the encryptor.
void
aesCBCencrypt(uchar *p, int len, AESstate *s)
{
	uchar *p2, *ip, *eip;
	uchar q[AESbsize];

	for(; len >= AESbsize; len -= AESbsize){
		p2 = p;
		ip = s->ivec;
		for(eip = ip+AESbsize; ip < eip; )
			*p2++ ^= *ip++;
		rijndaelEncrypt(s->ekey, s->rounds, p, q);
		memmove(s->ivec, q, AESbsize);
		memmove(p, q, AESbsize);
		p += AESbsize;
	}

	if(len > 0){
		ip = s->ivec;
		rijndaelEncrypt(s->ekey, s->rounds, ip, q);
		memmove(s->ivec, q, AESbsize);
		for(eip = ip+len; ip < eip; )
			*p++ ^= *ip++;
	}
}

void
aesCBCdecrypt(uchar *p, int len, AESstate *s)
{
	uchar *ip, *eip, *tp;
	uchar tmp[AESbsize], q[AESbsize];

	for(; len >= AESbsize; len -= AESbsize){
		memmove(tmp, p, AESbsize);
		rijndaelDecrypt(s->dkey, s->rounds, p, q);
		memmove(p, q, AESbsize);
		tp = tmp;
		ip = s->ivec;
		for(eip = ip+AESbsize; ip < eip; ){
			*p++ ^= *ip;
			*ip++ = *tp++;
		}
	}

	if(len > 0){
		ip = s->ivec;
		rijndaelEncrypt(s->ekey, s->rounds, ip, q);
		memmove(s->ivec, q, AESbsize);
		for(eip = ip+len; ip < eip; )
			*p++ ^= *ip++;
	}
}

/*
 * this function has been changed for plan 9.
 * Expand the cipher key into the encryption and decryption key schedules.
 *
 * @return	the number of rounds for the given cipher key size.
 */
static int rijndaelKeySetup(u32 erk[/*4*(Nr + 1)*/], u32 drk[/*4*(Nr + 1)*/], const u8 cipherKey[], int keyBits) {
	int Nr, i;

	/* expand the cipher key: */
	Nr = rijndaelKeySetupEnc(erk, cipherKey, keyBits);

	/*
	 * invert the order of the round keys and
	 * apply the inverse MixColumn transform to all round keys but the first and the last
	 */
	drk[0       ] = erk[4*Nr    ]; 
	drk[1       ] = erk[4*Nr + 1];
	drk[2       ] = erk[4*Nr + 2]; 
	drk[3       ] = erk[4*Nr + 3];
	drk[4*Nr    ] = erk[0       ]; 
	drk[4*Nr + 1] = erk[1       ];
	drk[4*Nr + 2] = erk[2       ]; 
	drk[4*Nr + 3] = erk[3       ];
	erk += 4 * Nr;
	for (i = 1; i < Nr; i++) {
		drk += 4;
		erk -= 4;
		drk[0] =
		    Td0[Te4[(erk[0] >> 24)       ]] ^
		    Td1[Te4[(erk[0] >> 16) & 0xff]] ^
		    Td2[Te4[(erk[0] >>  8) & 0xff]] ^
		    Td3[Te4[(erk[0]      ) & 0xff]];
		drk[1] =
		    Td0[Te4[(erk[1] >> 24)       ]] ^
		    Td1[Te4[(erk[1] >> 16) & 0xff]] ^
		    Td2[Te4[(erk[1] >>  8) & 0xff]] ^
		    Td3[Te4[(erk[1]      ) & 0xff]];
		drk[2] =
		    Td0[Te4[(erk[2] >> 24)       ]] ^
		    Td1[Te4[(erk[2] >> 16) & 0xff]] ^
		    Td2[Te4[(erk[2] >>  8) & 0xff]] ^
		    Td3[Te4[(erk[2]      ) & 0xff]];
		drk[3] =
		    Td0[Te4[(erk[3] >> 24)       ]] ^
		    Td1[Te4[(erk[3] >> 16) & 0xff]] ^
		    Td2[Te4[(erk[3] >>  8) & 0xff]] ^
		    Td3[Te4[(erk[3]      ) & 0xff]];
	}
	return Nr;
}

/*
Te0[x] = S [x].[02, 01, 01, 03];
Te1[x] = S [x].[03, 02, 01, 01];
Te2[x] = S [x].[01, 03, 02, 01];
Te3[x] = S [x].[01, 01, 03, 02];
Te4[x] = S [x]

Td0[x] = Si[x].[0e, 09, 0d, 0b];
Td1[x] = Si[x].[0b, 0e, 09, 0d];
Td2[x] = Si[x].[0d, 0b, 0e, 09];
Td3[x] = Si[x].[09, 0d, 0b, 0e];
Td4[x] = Si[x]
*/

static const u32 Te0[256] = {
    0xc66363a5U, 0xf87c7c84U, 0xee777799U, 0xf67b7b8dU,
    0xfff2f20dU, 0xd66b6bbdU, 0xde6f6fb1U, 0x91c5c554U,
    0x60303050U, 0x02010103U, 0xce6767a9U, 0x562b2b7dU,
    0xe7fefe19U, 0xb5d7d762U, 0x4dababe6U, 0xec76769aU,
    0x8fcaca45U, 0x1f82829dU, 0x89c9c940U, 0xfa7d7d87U,
    0xeffafa15U, 0xb25959ebU, 0x8e4747c9U, 0xfbf0f00bU,
    0x41adadecU, 0xb3d4d467U, 0x5fa2a2fdU, 0x45afafeaU,
    0x239c9cbfU, 0x53a4a4f7U, 0xe4727296U, 0x9bc0c05bU,
    0x75b7b7c2U, 0xe1fdfd1cU, 0x3d9393aeU, 0x4c26266aU,
    0x6c36365aU, 0x7e3f3f41U, 0xf5f7f702U, 0x83cccc4fU,
    0x6834345cU, 0x51a5a5f4U, 0xd1e5e534U, 0xf9f1f108U,
    0xe2717193U, 0xabd8d873U, 0x62313153U, 0x2a15153fU,
    0x0804040cU, 0x95c7c752U, 0x46232365U, 0x9dc3c35eU,
    0x30181828U, 0x379696a1U, 0x0a05050fU, 0x2f9a9ab5U,
    0x0e070709U, 0x24121236U, 0x1b80809bU, 0xdfe2e23dU,
    0xcdebeb26U, 0x4e272769U, 0x7fb2b2cdU, 0xea75759fU,
    0x1209091bU, 0x1d83839eU, 0x582c2c74U, 0x341a1a2eU,
    0x361b1b2dU, 0xdc6e6eb2U, 0xb45a5aeeU, 0x5ba0a0fbU,
    0xa45252f6U, 0x763b3b4dU, 0xb7d6d661U, 0x7db3b3ceU,
    0x5229297bU, 0xdde3e33eU, 0x5e2f2f71U, 0x13848497U,
    0xa65353f5U, 0xb9d1d168U, 0x00000000U, 0xc1eded2cU,
    0x40202060U, 0xe3fcfc1fU, 0x79b1b1c8U, 0xb65b5bedU,
    0xd46a6abeU, 0x8dcbcb46U, 0x67bebed9U, 0x7239394bU,
    0x944a4adeU, 0x984c4cd4U, 0xb05858e8U, 0x85cfcf4aU,
    0xbbd0d06bU, 0xc5efef2aU, 0x4faaaae5U, 0xedfbfb16U,
    0x864343c5U, 0x9a4d4dd7U, 0x66333355U, 0x11858594U,
    0x8a4545cfU, 0xe9f9f910U, 0x04020206U, 0xfe7f7f81U,
    0xa05050f0U, 0x783c3c44U, 0x259f9fbaU, 0x4ba8a8e3U,
    0xa25151f3U, 0x5da3a3feU, 0x804040c0U, 0x058f8f8aU,
    0x3f9292adU, 0x219d9dbcU, 0x70383848U, 0xf1f5f504U,
    0x63bcbcdfU, 0x77b6b6c1U, 0xafdada75U, 0x42212163U,
    0x20101030U, 0xe5ffff1aU, 0xfdf3f30eU, 0xbfd2d26dU,
    0x81cdcd4cU, 0x180c0c14U, 0x26131335U, 0xc3ecec2fU,
    0xbe5f5fe1U, 0x359797a2U, 0x884444ccU, 0x2e171739U,
    0x93c4c457U, 0x55a7a7f2U, 0xfc7e7e82U, 0x7a3d3d47U,
    0xc86464acU, 0xba5d5de7U, 0x3219192bU, 0xe6737395U,
    0xc06060a0U, 0x19818198U, 0x9e4f4fd1U, 0xa3dcdc7fU,
    0x44222266U, 0x542a2a7eU, 0x3b9090abU, 0x0b888883U,
    0x8c4646caU, 0xc7eeee29U, 0x6bb8b8d3U, 0x2814143cU,
    0xa7dede79U, 0xbc5e5ee2U, 0x160b0b1dU, 0xaddbdb76U,
    0xdbe0e03bU, 0x64323256U, 0x743a3a4eU, 0x140a0a1eU,
    0x924949dbU, 0x0c06060aU, 0x4824246cU, 0xb85c5ce4U,
    0x9fc2c25dU, 0xbdd3d36eU, 0x43acacefU, 0xc46262a6U,
    0x399191a8U, 0x319595a4U, 0xd3e4e437U, 0xf279798bU,
    0xd5e7e732U, 0x8bc8c843U, 0x6e373759U, 0xda6d6db7U,
    0x018d8d8cU, 0xb1d5d564U, 0x9c4e4ed2U, 0x49a9a9e0U,
    0xd86c6cb4U, 0xac5656faU, 0xf3f4f407U, 0xcfeaea25U,
    0xca6565afU, 0xf47a7a8eU, 0x47aeaee9U, 0x10080818U,
    0x6fbabad5U, 0xf0787888U, 0x4a25256fU, 0x5c2e2e72U,
    0x381c1c24U, 0x57a6a6f1U, 0x73b4b4c7U, 0x97c6c651U,
    0xcbe8e823U, 0xa1dddd7cU, 0xe874749cU, 0x3e1f1f21U,
    0x964b4bddU, 0x61bdbddcU, 0x0d8b8b86U, 0x0f8a8a85U,
    0xe0707090U, 0x7c3e3e42U, 0x71b5b5c4U, 0xcc6666aaU,
    0x904848d8U, 0x06030305U, 0xf7f6f601U, 0x1c0e0e12U,
    0xc26161a3U, 0x6a35355fU, 0xae5757f9U, 0x69b9b9d0U,
    0x17868691U, 0x99c1c158U, 0x3a1d1d27U, 0x279e9eb9U,
    0xd9e1e138U, 0xebf8f813U, 0x2b9898b3U, 0x22111133U,
    0xd26969bbU, 0xa9d9d970U, 0x078e8e89U, 0x339494a7U,
    0x2d9b9bb6U, 0x3c1e1e22U, 0x15878792U, 0xc9e9e920U,
    0x87cece49U, 0xaa5555ffU, 0x50282878U, 0xa5dfdf7aU,
    0x038c8c8fU, 0x59a1a1f8U, 0x09898980U, 0x1a0d0d17U,
    0x65bfbfdaU, 0xd7e6e631U, 0x844242c6U, 0xd06868b8U,
    0x824141c3U, 0x299999b0U, 0x5a2d2d77U, 0x1e0f0f11U,
    0x7bb0b0cbU, 0xa85454fcU, 0x6dbbbbd6U, 0x2c16163aU,
};
static const u32 Te1[256] = {
    0xa5c66363U, 0x84f87c7cU, 0x99ee7777U, 0x8df67b7bU,
    0x0dfff2f2U, 0xbdd66b6bU, 0xb1de6f6fU, 0x5491c5c5U,
    0x50603030U, 0x03020101U, 0xa9ce6767U, 0x7d562b2bU,
    0x19e7fefeU, 0x62b5d7d7U, 0xe64dababU, 0x9aec7676U,
    0x458fcacaU, 0x9d1f8282U, 0x4089c9c9U, 0x87fa7d7dU,
    0x15effafaU, 0xebb25959U, 0xc98e4747U, 0x0bfbf0f0U,
    0xec41adadU, 0x67b3d4d4U, 0xfd5fa2a2U, 0xea45afafU,
    0xbf239c9cU, 0xf753a4a4U, 0x96e47272U, 0x5b9bc0c0U,
    0xc275b7b7U, 0x1ce1fdfdU, 0xae3d9393U, 0x6a4c2626U,
    0x5a6c3636U, 0x417e3f3fU, 0x02f5f7f7U, 0x4f83ccccU,
    0x5c683434U, 0xf451a5a5U, 0x34d1e5e5U, 0x08f9f1f1U,
    0x93e27171U, 0x73abd8d8U, 0x53623131U, 0x3f2a1515U,
    0x0c080404U, 0x5295c7c7U, 0x65462323U, 0x5e9dc3c3U,
    0x28301818U, 0xa1379696U, 0x0f0a0505U, 0xb52f9a9aU,
    0x090e0707U, 0x36241212U, 0x9b1b8080U, 0x3ddfe2e2U,
    0x26cdebebU, 0x694e2727U, 0xcd7fb2b2U, 0x9fea7575U,
    0x1b120909U, 0x9e1d8383U, 0x74582c2cU, 0x2e341a1aU,
    0x2d361b1bU, 0xb2dc6e6eU, 0xeeb45a5aU, 0xfb5ba0a0U,
    0xf6a45252U, 0x4d763b3bU, 0x61b7d6d6U, 0xce7db3b3U,
    0x7b522929U, 0x3edde3e3U, 0x715e2f2fU, 0x97138484U,
    0xf5a65353U, 0x68b9d1d1U, 0x00000000U, 0x2cc1ededU,
    0x60402020U, 0x1fe3fcfcU, 0xc879b1b1U, 0xedb65b5bU,
    0xbed46a6aU, 0x468dcbcbU, 0xd967bebeU, 0x4b723939U,
    0xde944a4aU, 0xd4984c4cU, 0xe8b05858U, 0x4a85cfcfU,
    0x6bbbd0d0U, 0x2ac5efefU, 0xe54faaaaU, 0x16edfbfbU,
    0xc5864343U, 0xd79a4d4dU, 0x55663333U, 0x94118585U,
    0xcf8a4545U, 0x10e9f9f9U, 0x06040202U, 0x81fe7f7fU,
    0xf0a05050U, 0x44783c3cU, 0xba259f9fU, 0xe34ba8a8U,
    0xf3a25151U, 0xfe5da3a3U, 0xc0804040U, 0x8a058f8fU,
    0xad3f9292U, 0xbc219d9dU, 0x48703838U, 0x04f1f5f5U,
    0xdf63bcbcU, 0xc177b6b6U, 0x75afdadaU, 0x63422121U,
    0x30201010U, 0x1ae5ffffU, 0x0efdf3f3U, 0x6dbfd2d2U,
    0x4c81cdcdU, 0x14180c0cU, 0x35261313U, 0x2fc3ececU,
    0xe1be5f5fU, 0xa2359797U, 0xcc884444U, 0x392e1717U,
    0x5793c4c4U, 0xf255a7a7U, 0x82fc7e7eU, 0x477a3d3dU,
    0xacc86464U, 0xe7ba5d5dU, 0x2b321919U, 0x95e67373U,
    0xa0c06060U, 0x98198181U, 0xd19e4f4fU, 0x7fa3dcdcU,
    0x66442222U, 0x7e542a2aU, 0xab3b9090U, 0x830b8888U,
    0xca8c4646U, 0x29c7eeeeU, 0xd36bb8b8U, 0x3c281414U,
    0x79a7dedeU, 0xe2bc5e5eU, 0x1d160b0bU, 0x76addbdbU,
    0x3bdbe0e0U, 0x56643232U, 0x4e743a3aU, 0x1e140a0aU,
    0xdb924949U, 0x0a0c0606U, 0x6c482424U, 0xe4b85c5cU,
    0x5d9fc2c2U, 0x6ebdd3d3U, 0xef43acacU, 0xa6c46262U,
    0xa8399191U, 0xa4319595U, 0x37d3e4e4U, 0x8bf27979U,
    0x32d5e7e7U, 0x438bc8c8U, 0x596e3737U, 0xb7da6d6dU,
    0x8c018d8dU, 0x64b1d5d5U, 0xd29c4e4eU, 0xe049a9a9U,
    0xb4d86c6cU, 0xfaac5656U, 0x07f3f4f4U, 0x25cfeaeaU,
    0xafca6565U, 0x8ef47a7aU, 0xe947aeaeU, 0x18100808U,
    0xd56fbabaU, 0x88f07878U, 0x6f4a2525U, 0x725c2e2eU,
    0x24381c1cU, 0xf157a6a6U, 0xc773b4b4U, 0x5197c6c6U,
    0x23cbe8e8U, 0x7ca1ddddU, 0x9ce87474U, 0x213e1f1fU,
    0xdd964b4bU, 0xdc61bdbdU, 0x860d8b8bU, 0x850f8a8aU,
    0x90e07070U, 0x427c3e3eU, 0xc471b5b5U, 0xaacc6666U,
    0xd8904848U, 0x05060303U, 0x01f7f6f6U, 0x121c0e0eU,