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CCIE Sec Encryption Ipsec

Subjects : cisco, it-skills, ccie
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. The receiving device decrypts the data with the third key.






2. A






3. One of the most popular tunneling protocols is






4. 'Finally - the receiving devices decrypt the data with the first key.'






5. Common key size is 1024 bits.






6. The sending device encrypts for a final time with another 56-bit key.






7. Benefits are that the preshared authentication can be based on ID versus IP address and the speed of the process.






8. Takes variable-length clear-text data to produce fixed-length hashed data that is unreadable.






9. The DES algorithm that performs 3 times sequentially.






10. 'group 1 identifies a 768-bit key - group 1 is faster to execute - but it is less secure -'






11. Turns clear-text data into cipher text with an encryption algorithm. The receiving station decrypts the data from cipher text into clear text. The encryption key is a shared secret key that encrypts and decrypts messages.






12. 'A 56-bit encryption algorithm - meaning the number of possible keys






13. Used in IPsec for two discreet purposes:






14. Provides authentication and encryption of the payload.






15. Where the original Layer 3 header and payload inside an IPsec packet is encapsulated. Tunnel mode does add overhead to each packet and uses some additional CPU resources.






16. DoS attacks are more probable with this mode.






17. Is a two-phase protocol: The first phase establishes a secure authenticated channel and the second phase is where SAs are negotiated on behalf of the IPsec services.






18. 'algorithm encrypts and decrypts data three times with 3 different keys - effectively creating a 168-bit key.'






19. A variable block- length and key-length cipher.






20. 'establishes ISAKMP SA in three messages -because it negotiates a ISAKMP policy and a DJ nonce exchange together.'






21. Act of encapsulating a packet within another packet.






22. It uses UDP 500 and is defined by RFC 2409.






23. IPSec SAs are negotiated and protected by the existing IPsec SA.






24. Main mode establishes ISAKMP security association in six messages and performs authenticated D-H exchange.






25. 'Message digest algorithms have a drawback whereby a hacker (man in the middle) can intercept a message containing the packet and hash values - then re-create and transmit a modified packet with the same calculated hash to the target destination.'






26. Data integrity is the process of making sure data is not tampered with while it






27. Negotiation of the ISAKMP policy by offering and acceptance of protection suites


28. 'key exchange is vulnerable to a man-in-the-middle attack. You can rectify this problem by allowing the two parties to authenticate themselves to each other with a shared secret key - digital signatures - or public-key certificates.'






29. That authenticate data packets and ensure that data is not tampered with or modified.






30. The protocol of choice for key management and establishing security associations between peers on the Internet.






31. Drawback of this is that the hash is passed unencrypted and is susceptible to PSK crack attacks.






32. 'is a block-cipher algorithm - which means that it performs operations on fixed-length data streams of 64-bit blocks. The key ostensibly consists of 64 bits; however - only 56 are actually used by the algorithm.'






33. 'including Internet Security Association and Key Management Protocol (ISAKMP) - Secure Key Exchange Mechanism for the Internet (SKEME) - and Oakley.'






34. 'produces a 160-bit hash output - which makes it more difficult to decipher.'






35. Provide authentication in Internet Key Exchange (IKE) Phase 2.






36. Integrity checks are done


37. Has a trailer which identifies IPsec information and ESP integrity-check information.






38. 'Encryption - where Peer X uses Peer Y






39. Origin authentication validates the origin of a message upon receipt; this process is done during initial communications.






40. 'The messages are authenticated - and the mechanisms that provide such integrity checks based on a secret key are usually called'






41. More CPU intensive






42. Negotiation of the ISAKMP policy by offering and acceptance of protection suites






43. 'DSA is roughly the same speed as RSA when creating signatures - but 10 to 40 times slower when verifying signatures. Because verification happens more frequently than creation - this issue is worth noting when deploying DSA in any environment.'






44. IPSEC Encryption is performed by


45. You check it by hashing data and appending the hash value to the data as you send it across the network to a peer.






46. 'can be achieved using one of three methods: preshared keys - encrypted nonces - or digital signatures.'






47. 'requires that the sender and receiver have key pairs. By combining the sender






48. 'often called public-key algorithms - do not rely on a randomly generated shared encryption key; instead - they create two static keys. These static keys are completely different - but mathematically bound to each other; what one key encrypts - the o






49. Does not provide payload encryption.






50. Message of arbitrary length is taken as input and produces as output a 128-bit fingerprint or message digest of the input.