aes_api.c

RMI的处理器au1200系列所用的BOOTLOAD,包括SD卡启动USB启动硬盘启动网络启动,并初始化硬件的所有参数,支持内核调试.

/**
 * @file aes_api.c
 *
 * @brief	interface for NIST AES implementation, OFB decryption only
 *
 * @date @(#) Sep 21 2004, 09:28:38
 *
 * @author Reinhard Wobst
 */

#include "aes_ref_encr.h"
#include "aes_api.h"

/* help function */
static void encrypt_one_block(unsigned char *block);

/* static data */
static unsigned char *Iv;
static int Counter;
static ROUNDKEYS *roundkeys;

/**
 * @brief initialize AES OFB decryption
 *
 * @param key	the 128 bit key
 * @param iv	the 128 bit initialization vector
 * @param rky	pointer to workspace for round keys
 */

void decrypt_aes_init(unsigned char key[], unsigned char *iv,
		      ROUNDKEYS * rky)
{
    unsigned char keytab[4][MAXBC];
    int i;

    roundkeys = rky;

    for (i = 4 * 4; i--;)
	keytab[i % 4][i / 4] = key[i];
    rijndaelKeySched(keytab, 128, 128, *roundkeys);

    Counter = 0;
    Iv = iv;
    encrypt_one_block(Iv);
}

/**
 * @brief decrypt piece of AES OFB enciphered text
 *
 * @param block	[in,out] the ciphertext, will be overwritten by
 * 		plaintext
 * @param len	number of bytes to decrypt
 */

void decrypt_aes_ofb(unsigned char *block, int len)
{
    register int i;
    register unsigned char *piv = Iv + Counter;

    if (Counter) {
	while (Counter < 16 && len > 0) {
	    *block++ ^= *piv++;
	    ++Counter;
	    --len;
	}
	if (!len)
	    return;
	encrypt_one_block(Iv);
	piv = Iv;
	Counter = 0;
    }

    /* now counter == 0 */
    while (len >= 16) {
	for (i = 16; i--;)
	    *block++ ^= *piv++;
	piv = Iv;
	encrypt_one_block(Iv);
	len -= 16;
    }

    /* still Counter == 0, len < 16 */
    while (len) {
	*block++ ^= *piv++;
	--len;
	++Counter;
    }
}

/**
 * @brief	encrypt one AES block
 *
 * @param block	the block
 */

static void encrypt_one_block(unsigned char *block)
{
    register int j, t;
    unsigned char table[4][MAXBC];

    /* parse input stream into rectangular array */
    for (j = 0; j < 4; j++)
	for (t = 0; t < 4; t++)
	    table[t][j] = block[4 * j + t] & 0xFF;

    rijndaelEncrypt(table, 128, 128, *roundkeys);

    /* parse rectangular array into output ciphertext bytes */
    for (j = 0; j < 4; j++)
	for (t = 0; t < 4; t++)
	    block[4 * j + t] = table[t][j];
}