Write from cybok knownledge book page 338 :: Historically, there have been four traditional
modes of operation to turn a block cipher into an encryption algorithm. These were ECB, CBC, OFB and
CFB modes. In recent years, the CTR mode has also been added to this list. Among these, only CBC mode
(given in Figure 10.2) and CTR mode (given in Figure 10.3) are used widely within current systems
On their own, however, CBC and CTR modes only provide IND-CPA security. This is far weaker than the
‘gold standard’ of security, namely IND-CCA (discussed earlier).
Write from wiki :: In cryptography, forward secrecy (FS), also known as perfect forward
secrecy (PFS), is a feature of specific key agreement protocols that gives assurances that session
keys will not be compromised even if long-term secrets used in the session key exchange are
compromised. For HTTPS the long-term secret is typically the private signing key of the server.
Forward secrecy protects past sessions against future compromises of keys or passwords. By
generating a unique session key for every session a user initiates, the compromise of a single
session key will not affect any data other than that exchanged in the specific session protected by
that particular key. This by itself is not sufficient for forward secrecy which additionally requires that a
long-term secret compromise does not affect the security of past session keys.
What is station to station protocol ?
In a two-party authenticated key exchange, the legitimate parties can
compute a secret key, while at the same time being certain about the
authenticity of the parties with whom they exchange a key. The
scheme must, in particular, be secure against a man-in-the-middle
attack
.
A popular authenticated version of the Diffie–Hellman key exchange
protocol
is the Station-to-Station protocol
. It was proposed by Diffie–
van Oorschot–Wiener
