[Q] What exactly is different about Safestrap than other recoveries?

[MaliciousBanjo]

I haven't flashed a new ROM in quite a while and I've been quite happy with TWRP for quite some time now.
I've started looking around again, and there seems to be a lot of push for Safestrap Recovery-oriented ROMs.

What exactly is it? From what I've gathered, it's a recovery that doesn't directly interact with a bootloader, so you can still have a recovery even if your bootloader is locked?

If that's true, why is it necessary, especially for the Galaxy S4? I'm running the ATT version and unlocked the bootloader with no problems over a year ago.

 

[jmjoyas]

The boot loader has never been unlocked on the ATT S4. The initial ones (MDB &MDL) had a bug that Loki exploited and allowed for replacing the kernel and recovery.
That bug got fixed in MF3.
Safestrap recovery doesn't replace the stock recovery and is available during the normal boot itself.
People with newer firmware on ATT S4 have no choice but to use safestrap.

 

[RockRatt]

With MDB or MDL bootloader you used the loki bootloader bypass. YOUR bootloader IS STILL LOCKED down, but the LOKI BYPASS allowed us to run twrp. Loki is what allowed for using twrp. With twrp you can flash ANY Roms, modems, KERNELS. Pretty much can flash anything as long as you Loki the kernel. You can run AOSP based Roms like CM, AOKP, Etc.

For those that got there phone AFTER MF3 bootloader and Newer the exploit that allowed LOKI and TWRP was fixed. Those users are stuck using Touchwiz based Roms that run the stock ATT kernel and can ONLY use safestrap recovery. Safestrap recovery can ONLY flash Touchwiz based Roms (except maybe a small few converted Roms like google based Roms that can use the stock ATT kernel). As safestrap CANNOT flash modified kernels, so no custom kernels to undervolt/over volt/ etc. This also means no AOSP based Roms for the most part.