Function mbedtls_internal_aes_decrypt

lite/src/decryption/mbedtls/aes.cc:762–812

 */
#if !defined(MBEDTLS_AES_DECRYPT_ALT)
int mbedtls_internal_aes_decrypt(mbedtls_aes_context *ctx,
                                 const unsigned char input[16],
                                 unsigned char output[16]) {
    int i;
    uint32_t *RK, X0, X1, X2, X3, Y0, Y1, Y2, Y3;

    RK = ctx->rk;

    GET_UINT32_LE(X0, input, 0);
    X0 ^= *RK++;
    GET_UINT32_LE(X1, input, 4);
    X1 ^= *RK++;
    GET_UINT32_LE(X2, input, 8);
    X2 ^= *RK++;
    GET_UINT32_LE(X3, input, 12);
    X3 ^= *RK++;

    for (i = (ctx->nr >> 1) - 1; i > 0; i--) {
        AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);
        AES_RROUND(X0, X1, X2, X3, Y0, Y1, Y2, Y3);
    }

    AES_RROUND(Y0, Y1, Y2, Y3, X0, X1, X2, X3);

    X0 = *RK++ ^ ((uint32_t)RSb[(Y0)&0xFF]) ^
         ((uint32_t)RSb[(Y3 >> 8) & 0xFF] << 8) ^
         ((uint32_t)RSb[(Y2 >> 16) & 0xFF] << 16) ^
         ((uint32_t)RSb[(Y1 >> 24) & 0xFF] << 24);

    X1 = *RK++ ^ ((uint32_t)RSb[(Y1)&0xFF]) ^
         ((uint32_t)RSb[(Y0 >> 8) & 0xFF] << 8) ^
         ((uint32_t)RSb[(Y3 >> 16) & 0xFF] << 16) ^
         ((uint32_t)RSb[(Y2 >> 24) & 0xFF] << 24);

    X2 = *RK++ ^ ((uint32_t)RSb[(Y2)&0xFF]) ^
         ((uint32_t)RSb[(Y1 >> 8) & 0xFF] << 8) ^
         ((uint32_t)RSb[(Y0 >> 16) & 0xFF] << 16) ^
         ((uint32_t)RSb[(Y3 >> 24) & 0xFF] << 24);

    X3 = *RK++ ^ ((uint32_t)RSb[(Y3)&0xFF]) ^
         ((uint32_t)RSb[(Y2 >> 8) & 0xFF] << 8) ^
         ((uint32_t)RSb[(Y1 >> 16) & 0xFF] << 16) ^
         ((uint32_t)RSb[(Y0 >> 24) & 0xFF] << 24);

    PUT_UINT32_LE(X0, output, 0);
    PUT_UINT32_LE(X1, output, 4);
    PUT_UINT32_LE(X2, output, 8);
    PUT_UINT32_LE(X3, output, 12);

    return (0);
}
#endif /* !MBEDTLS_AES_DECRYPT_ALT */

/*