End-to-end encryption (E2EE) is the encryption of transmitted data across all transmission stations. Only the communication partners (the respective end points of the communication) can decrypt the message.
When using symmetric encryption, the key to ensure end-to-end encryption must only be known to the end communication partners. When using asymmetric encryption, it must be ensured that the secret key (private key) is exclusively in the possession of the recipient.
The data to be transmitted is encrypted on the sender side and only decrypted again at the receiver. This means that side-channel information, such as that which is partly used to control the transmission process, cannot be encrypted, and, on the other hand, that intermediate stations with knowledge of the transmitted content are eliminated. End-to-end encryption therefore guarantees complete protection of the transmitted data packets and fulfils three important goals of encryption on the Internet: Confidentiality, authenticity and integrity. End-to-end encryption prevents eavesdropping on the message by anyone else, including telecommunications providers, Internet providers and even the provider of the communication services used.