> For the complete documentation index, see [llms.txt](https://docs.cypherock.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cypherock.com/design-decisions/cypherock-x1-hardware-architecture/using-javacards-instead-of-microsd.md).

# Using Javacards instead of MicroSD

There were a few key points that led to the usage of Javacards in comparison to SD Cards: 

1. Users cannot check the genuinity of the SD card because custom logic can not be implemented. 
2. MicroSD cards do not have flexible brute force prevention schemes.
3. Users can not directly communicate with phones through a MicroSD card. Javacards are NFC based and hence can directly communicate.
4. Since SD cards can not encrypt/decrypt data on its own, this inability hinders future product development and features, especially when it comes to working on crypto inheritance. 
5. Javacards are battle tested for decades in the banking industry for developing credit and debit cards whereas Micro SD cards are more generally used for larger storage of non-sensitive information.