hi my friend told me he can install and hide one app (spy app) on my phone, and that app can send all messages come out from my phone to him (leak my conversation even the secret chat) , is that right ? I hope you can understand me (English not good). and as i know signal private messenger should be full encrypted (end to end )
With physical access to your android or computer, an attacker(friend?) can do almost anything. On older iPhones it's a bit harder, on new models almost imposible, without knowing your credentials. If the attacker is an nation side hacker, your lost.
If you are asking if Signal is safer compared than other messaging apps, the answer is yes. But if your device already has malware, then as with nearly all cybersecurity matters, physical access to either device or user or both changes things considerably. Signal is SECURE.
how could I know if someone install and hide spy apps in my phone? is there any app can search for that and find it ? thanks for helping
Short answer: no If you are concerned about someone spies your conversations, I recommend to use Tails Linux live, on and prior UEFI Notebook, or PC, that has no hard disk.. https://tails.boum.org
I meant: There is no way to find out, if your android is compromised, or not. That's why I recommended Trails live on an older PC, best with BIOS, not UEFI.
