Implement Ende-in-Ende Verschlüsselung (E2EE)
Ende-in-Ende Verschlüsselung ensures nur der communicating parties kann lesen messages — kein intermediary Server holds Entschlüsselung Schlüssel. Lernen der hybrid Verschlüsselung Muster.
- 1
E2EE uses hybrid encryption: a symmetric key (AES) encrypts the message, and the recipient's public key (RSA/ECDSA) encrypts the symmetric key. The server stores only ciphertext. The recipient decrypts the symmetric key with their private key, then decrypts the message.
- 2 AES-Verschlüsseler →
Verschlüsseln the message with a fresh random AES-256 key. This key is generated per message and never reused. The ciphertext is what gets stored and transmitted.
- 3 RSA-Tool →
Verschlüsseln the AES key with the recipient's RSA public key. The recipient's private key is needed to recover the AES key. This is the key encapsulation step.
- 4 HMAC-Generator →
Erzeugen an HMAC over the ciphertext to detect tampering in transit. The recipient verifies the HMAC before attempting decryption.
- 5
For messaging apps, each user has a long-term identity key pair. For forward secrecy, use ephemeral Diffie-Hellman per session: generate a temporary key pair, exchange public keys, derive a shared secret, and discard the ephemeral keys after the session.
Häufige Fragen
- Why hybrid encryption instead of just RSA?
- RSA is slow and has a size limit (plaintext must be smaller than the modulus). AES is fast and handles any size. Hybrid combines the strengths: RSA for key exchange, AES for bulk data.
- Can the server decrypt E2EE messages?
- No — by design. The server only stores ciphertext and encrypted keys. Only the recipient's device has the private key. This is the defining property of E2EE, but it means the server cannot provide search or backup features without client-side decryption.