Free SSCP Questions Attempt

As session key is a symmetric key that is used to encrypt messages between two users. A session key is only good for one communication session between users.

For example , If Tanya has a symmetric key that she uses to encrypt messages between Lance and herself all the time , then this symmetric key would not be regenerated or changed. They would use the same key every time they communicated using encryption. However , using the same key repeatedly increases the chances of the key being captured and the secure communication being compromised. If , on the other hand , a new symmetric key were generated each time Lance and Tanya wanted to communicate , it would be used only during their dialog and then destroyed. if they wanted to communicate and hour later , a new session key would be created and shared.

The other answers are not correct because :

Public Key can be known to anyone.

Private Key must be known and used only by the owner.

Secret Keys are also called as Symmetric Keys, because this type of encryption relies on each user to keep the key a secret and properly protected.

REFERENCES:

SHON HARRIS , ALL IN ONE THIRD EDITION : Chapter 8 : Cryptography , Page : 619-620

Wireless Transport Layer Security (WTLS) is a communication protocol that allows wireless devices to send and receive encrypted information over the Internet. S-WAP is not defined. WSP (Wireless Session Protocol) and WDP (Wireless Datagram Protocol) are part of Wireless Access Protocol (WAP).

Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 4: Cryptography (page 173).

All other properties above apply to the Rijndael algorithm, chosen as the AES standard to replace DES.

The AES algorithm is capable of using cryptographic keys of 128, 192, and 256 bits to encrypt and decrypt data in blocks of 128 bits. Rijndael was designed to handle additional block sizes and key lengths, however they are not adopted in the AES standard.

IDEA cipher algorithm operates on 64-bit plaintext blocks and uses a 128 bit key.

Reference(s) used for this question:

http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf

and

http://en.wikipedia.org/wiki/Advanced_Encryption_Standard

While a digital signature binds a document to the possessor of a particular key, a digital timestamp binds a document to its creation at a particular time.

Trusted timestamping is the process of securely keeping track of the creation and modification time of a document. Security here means that no one — not even the owner of the document — should be able to change it once it has been recorded provided that the timestamper's integrity is never compromised.

The administrative aspect involves setting up a publicly available, trusted timestamp management infrastructure to collect, process and renew timestamps or to make use of a commercially available time stamping service.

A modern example of using a Digital Timestamp is the case of an industrial research organization that may later need to prove, for patent purposes, that they made a particular discovery on a particular date; since magnetic media can be altered easily, this may be a nontrivial issue. One possible solution is for a researcher to compute and record in a hardcopy laboratory notebook a cryptographic hash of the relevant data file. In the future, should there be a need to prove the version of this file retrieved from a backup tape has not been altered, the hash function could be recomputed and compared with the hash value recorded in that paper notebook.

According to the RFC 3161 standard, a trusted timestamp is a timestamp issued by a trusted third party (TTP) acting as a Time Stamping Authority (TSA). It is used to prove the existence of certain data before a certain point (e.g. contracts, research data, medical records,...) without the possibility that the owner can backdate the timestamps. Multiple TSAs can be used to increase reliability and reduce vulnerability.

The newer ANSI ASC X9.95 Standard for trusted timestamps augments the RFC 3161 standard with data-level security requirements to ensure data integrity against a reliable time source that is provable to any third party. This standard has been applied to authenticating digitally signed data for regulatory compliance, financial transactions, and legal evidence.

Digital TimeStamp

The following are incorrect answers:

Network Time Protocol (NTP) is used to achieve high accuracy time synchronization for computers across a network.

A Certification Authority (CA) is the entity responsible for the issuance of digital certificates.

A Digital Signature provides integrity and authentication but does not bind a document to a specific time it was created.

Reference used for this question:

http://en.m.wikipedia.org/wiki/File:Trusted_timestamping.gif

and

http://en.wikipedia.org/wiki/Trusted_timestamping