void AESInit(AESInfo_t *aesInfoP) { unsigned char i; unsigned char *pExpandKey;//扩展密钥 unsigned char Rcon[4] = {0x01, 0x00, 0x00, 0x00}; switch (aesInfoP->type) { case AES128: aesInfoP->Nr = 10; aesInfoP->Nk = 16; break; case AES192: aesInfoP->Nr = 12; aesInfoP->Nk = 24; break; case AES256: aesInfoP->Nr = 14; aesInfoP->Nk = 32; break; default: aesInfoP->Nr = 10; aesInfoP->Nk = 16; break; } //拓展密匙 memcpy(aesInfoP->expandKey, aesInfoP->key, 4 * aesInfoP->Nk);//第一个是原始密匙， pExpandKey = &aesInfoP->expandKey[4*aesInfoP->Nk]; //拓展密匙AES128:10个、AES192:12个、AES256:14个 for (i = aesInfoP->Nk; i < Nb*(aesInfoP->Nr + 1); pExpandKey += 4, i++) { memcpy(pExpandKey, pExpandKey - 4, 4); if (0 == i % aesInfoP->Nk) { RShiftWord(pExpandKey); SubstituteBytes(pExpandKey, 4, SBox); XorBytes(pExpandKey, Rcon, 4); Rcon[0] = GfMultBy02(Rcon[0]); } else if (6 < aesInfoP->Nk && i % aesInfoP->Nk == Nb) { SubstituteBytes(pExpandKey, 4, SBox); } XorBytes(pExpandKey, pExpandKey - 4 * aesInfoP->Nk, 4); } } 解释每段代码的意思

这段代码是AES加密算法的初始化函数，主要作用是填充AESInfo_t结构体的各项参数，并生成扩展密钥。具体解释如下：

void AESInit(AESInfo_t *aesInfoP) {
    unsigned char i;
    unsigned char *pExpandKey;  // 指向扩展密钥的指针
    unsigned char Rcon[4] = {0x01, 0x00, 0x00, 0x00};  // 轮常数数组

    switch (aesInfoP->type) {
        case AES128:
            aesInfoP->Nr = 10;  // 轮数
            aesInfoP->Nk = 16;  // 密钥长度（字节）
            break;
        case AES192:
            aesInfoP->Nr = 12;
            aesInfoP->Nk = 24;
            break;
        case AES256:
            aesInfoP->Nr = 14;
            aesInfoP->Nk = 32;
            break;
        default:
            aesInfoP->Nr = 10;
            aesInfoP->Nk = 16;
            break;
    }

    // 拓展密匙
    memcpy(aesInfoP->expandKey, aesInfoP->key, 4 * aesInfoP->Nk);  // 复制原始密钥到扩展密钥的前Nk个字节
    pExpandKey = &aesInfoP->expandKey[4*aesInfoP->Nk];  // 指向扩展密钥的第Nk个字节（即原始密钥之后）

    for (i = aesInfoP->Nk; i < Nb*(aesInfoP->Nr + 1); pExpandKey += 4, i++) {
        memcpy(pExpandKey, pExpandKey - 4, 4);  // 复制前一个4字节到当前位置

        if (0 == i % aesInfoP->Nk) {  // 每Nk个字节进行一次特殊处理
            RShiftWord(pExpandKey);  // 字节循环左移一位
            SubstituteBytes(pExpandKey, 4, SBox);  // 字节替换
            XorBytes(pExpandKey, Rcon, 4);  // 字节异或轮常数

            Rcon[0] = GfMultBy02(Rcon[0]);  // 计算下一个轮常数
        } else if (6 < aesInfoP->Nk && i % aesInfoP->Nk == Nb) {  // 对于AES-256而言，每4*Nk个字节进行一次特殊处理
            SubstituteBytes(pExpandKey, 4, SBox);  // 字节替换
        }

        XorBytes(pExpandKey, pExpandKey - 4 * aesInfoP->Nk, 4);  // 与前Nk个字节异或
    }
}

上述代码中，Nb表示列数，对于AES而言，Nb=4。而SBox和GfMultBy02是AES算法中使用的两个表格和一个算法，用于字节替换和轮常数计算。具体实现细节可以参考AES算法的原理和流程。