Public Key Verschlüsselung
Public Key wird verwendet um zu verschlüsseln
Private Key wird zum entschlüsseln verwendet
Kein Schlüssel wird mit der Nachricht versendet
Typen der Public Key Algorithmen
- Diffie-Hellman: Erfinder der Public Key Verschlüsselung in 1976
- populär durch PGP
- verwendet SHA Hash Algorithmus
- RSA: erstellt durch Rivest, Shamir & Adleman
- Verwendung in PGP, Netscape Browser, etc.
- verwendet MD5 Hash Algorithmus
Notes:
Asymmetric or Public Key:
The encryption and decryption keys are different, but mathematically related
Only since 1976
Used in conjunction with symmetric cryptography
Why use both private & public encryption?
Public key cryptography enables digital signatures. This allows for non-repudiation and authenticity.
Public key cryptography is typically used to encrypt symmetric keys which are then safely exchanged.
Why not public key cryptography for all encryption?
100 to 1000 times slower than symmetric cryptography.
Why not use only symmetric cryptography?
You would need [n*(n-1) / 2] keys to be able to communicate securely to all parties, assuming you had a secure manner to distribute the keys.
The U.S. Department of Commerce license permis to enable 128-bit encryption security between banks and their customers in products that support the secure sockets layer (SSL) or transport layer security (TLS) protocols. Previously, U.S. export laws limited U.S. software products to no more than 64-bit encryption for financial data.
The 128-bit encryption capability is implemented as an extension to the SSL and TLS protocols. TLS is a security protocol overseen by a working group of the Internet Engineering Task Force, an Internet standards body. The extension enables an application to "switch on" 128-bit security when a digital certificate is present on the bank's system. If there is no certificate, the server and client negotiate the strongest common security available to them.