lots of times you have an encrypted tunnel to facebook or your bank or whatever The other person will also have a encrypted tunnel to facebook but facebook is in the middle and can read whatever you type, modify it, do what they want.. in this case the ‘end’ of the encryption is facebook itself
this protects you from everyone else trying to spy on your messages but doesn’t protect you from facebook itself
end to end encryption you have a encrypted tunnel from you to the person you’re messaging, no one in the middle, no one else can read it, you’re protected from everyone even from facebook itself from reading, modifying, using it for AI, submitted it to the CIA, etc..
then again you’re trusting facebook to protecting you from.. facebook and they didn’t just fail to tell you they still gave themselves a backdoor or something
Your computer and and my computer have a cypher that only we know, no one else knows it. Like a secret language. If I write something to you, my computer translates it into nonsense using our cypher so that if anyone else intercepts my message it would just look like garbage. But because your computer knows how to translate my message, it comes through normally for you. Like spies lol
It’s encrypting the messages “end-to-end” meaning the encryption/decryption takes place only in your device and the recipient’s device. This is different from the encryption happening at a middle stage, like for example you send a message, it goes to a central server, gets encrypted, then leaves, reaches another server, gets decrypted, and then reaches it’s destination. This basically means that nobody in between the two devices has access to the messages even if they have the data because it’s encrypted.
When you send most messages over the internet the message is encrypted between you and the server – facebook or whatever. It will then encrypt the message and send it to the person you are chatting with. This leaves a gap where fb can read your messages. End to end encryption is setup so that only you and the other person you are communicating with know what is said.
In addition to the other answers, here’s another perspective. Suppose you are sending a message to me.
Suppose someone wants to snoop on what you are sending. Suppose it is Facebook, or the government, with mega-resources to tap your phone or internet line. This is called a “man in the middle” attack. If they could do that, they could pretend to be me and fool you into thinking that it is indeed me. They read the message, maybe even change critical bits of that info, then send the modified message to me, pretending to be you. I believe the message thinking it is from you.
The only way to prevent this is that you encrypt it in such a way that the only party that can possibly decrypt it is me. Then even if someone managed to snoop your wire, they’ll have a bunch of binary gobbledygook. At most they can prevent the message from reaching me, but they cannot read or alter your message. It is secure from your end to my end.
There are lots of steps that occur when you send a message, it doesn’t just go straight from your device to the person you’re talking with’s device. It stops at the companies servers along the way. This is how you can get the message on several devices, each device downloads them from the companies servers.
Before end-to-end encryption came about the messages would be encrypted by your device, sent to the server and decrypted using a key that only you and the server knew to stop anyone intercepting them en route. They would then be reencrypted by the server and sent to the device the person you are talking to using a key that only they and the server knew. Their device would decrypt the message and show it to them.
The servers would store a copy of this message, encrypted using the key they use to send the message on, or perhaps using a different key only known to the server. But if LEA (law enforcement agencies) ever needed to get the messages, they could get a warrant and demand the company hand over the messages, decrypted. The companies had to comply.
Then end-to-end encryption was implemented. Now when you start a chat with someone the server introduces you to each other and the very first thing your device does is agree a new private key with the other device, and they do this directly without anything going to the servers. Now only your device and the device you are communicating with know the keys to decrypt messages.
Your device encrypts the message using this private key, sends it to the server and the server stores a copy as before, but no matter what they can’t decrypt the message and read the contents as they don’t have the key. They just forward the message on to the other person’s device and it gets decrypted there.
LEA can get a warrant and the companies will had over the encrypted messages, but because they’re encrypted they’re just gibberish. No matter what court order is made, because the company doesn’t have access to the private key needed to decrypt the messages they cannot give LEA what they want.
Basically, if you sent the message directly, any internet middlemen can read what you send, encryption is like making a secret code that only you and your friend know, you type the message in normal human language, the computer changes it to the secret code and then once your friend’s computer receives it, it changes it back to normal text, there is no way for anyone to read your messages except you and your friend.
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