Introduction To Cryptography; Encryption - D-Link DFL-1600 User Manual

20.2. Introduction to Cryptography

Another solution is required.
From a connectivity and security perspective, Virtual Private Networks
may still be viewed as "fixed connections" in that they do provide
connectivity between two or more organizations. This is a fact that does
not change even though Cryptography is deployed to implement the
"Virtual" side of the "Private Network".
20.2 Introduction to Cryptography
Cryptography provides a means to create "Virtual Private Networks"
across the Internet with no additional investments in cables, leased lines, or
other connectivity. It is an umbrella expression covering three basic
techniques and benefits:
Confidentiality
No one but the intended recipients is able to intercept and understand
the communication. Confidentiality is accomplished by encryption.
Authentication & Integrity
Proof for the recipient that the communication was actually sent by
the expected sender, and that the data has not been modified in
transit. This is accomplished by authentication, often by use of
cryptographic keyed hashes.
Non-repudiation
Proof that the sender actually sent the data; the sender cannot later
deny having sent it. Non-repudiation is usually a benign side-effect of
authentication.
20.2.1

Encryption

Encryption is a process of encoding sensitive information from plaintext to
unreadable ciphertext through some mathematical algorithms. The
operation of the algorithms is varied and usually parameterized by a large
random number, known as a key. The ciphertext is encrypted by the key
and it needs the same key or a related key to perform the reverse procedure
– decryption, to return to the original plaintext.
The algorithms of Encryption can be categorized into three types –
symmetric, asymmetric, and hybrid encryption.
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