small Continued:
have you a short time at you tube?
have phun: https://www.youtube.com/watch?v=Q0VWK4UHcg8
extended:
1st step was done:
i tested an open src bootloader named 'rboot'
i extended open src Bootloader with AES256 support in a test (aes256.a)
user firmware is on the SDHC
next step:
- 2) user firmware is encrypted on the SDHC and will decrypt on the fly
- 3) bootloader is on sdhc and esp will boot from sd card without flash ic
- 4)
be surprised!
continued Description and final code will follows later time with a projekt.
best wishes
rudi 
info: opens src bootloader
https://github.com/raburton/esp8266/tree/master/rboot
rBoot is designed to be a flexible open source boot loader, a replacement for
the binary blob supplied with the SDK. It has the following advantages over the
Espressif loader:
- Open source (written in C) 
- Supports up to 256 roms. 
- Roms can be variable size. 
- Able to test multiple roms to find a valid backup (without resetting). 
- Flash layout can be changed on the fly (with care and appropriately linked 
rom images).
- GPIO support for rom selection. 
- Wastes no stack space (SDK boot loader uses 144 bytes). 
- Documented config structure to allow easy editing from user code. 
- Can validate .irom0.text section with checksum. 
Statistics: Posted by rudi — Fri Aug 28, 2015 10:21 pm
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