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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. Uses the D-H algorithm to come to agreement over a public network.






2. 'defines the mode of communication - creation - and management of security associations.'






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






4. 'The sending device decrypts the data with the second key - which is also 56 bits in length.'






5. Provides authentication and encryption of the payload.






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






7. No additional Layer 3 header is created. The original Layer 3 header is used.






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






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






10. 'key lengths are 128 - 192 - or 256 bits to encrypt blocks of equal length.'






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






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






13. Main disadvantage of asymmetric algorithms is that they are slow.






14. Used in IPsec for two discreet purposes:






15. '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.'






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






17. This mode does not support identity protection or protection against clogging attacks and spoofing.






18. Common key size is 1024 bits.






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


20. DoS attacks are more probable with this mode.






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






22. You use this encryption method by keeping one key private and giving the other key to anyone in the public Internet. It does not matter who has your public key; it is useless without the private key.






23. 'Digital signatures. Peer X encrypts a hash value with his private key and then sends the data to Peer Y. Peer Y obtains Peer X






24. It also provides protection for ISAKMP peer identities with encryption.






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






26. The receiving device then encrypts the data with the second key.






27. 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.






28. Uses protocol number 51.






29. 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.






30. The DES algorithm that performs 3 times sequentially.






31. IPSEC tunnels data through IP using one of two protocols?






32. 'MACs with hash algorithms -'






33. The receiving device decrypts the data with the third key.






34. '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.'






35. Used for integrity checks on peer and data sent by peer and for authentication checks.






36. ' is defined in RFC 3174. has as output a 160-bit value -'






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






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






39. RFC 2631 on the workings of the key generation/exchange process.






40. Uses protocol number 50.






41. Hybrid protocol that defines the mechanism to derive authenticated keying material and negotiation of security associations (SA).






42. IPSEC performs this function by using a sequence field in the IPsec header combined with integrity checks.






43. 'is a more secure version of MD5 - and hash-based message authentication codes (HMAC) provides further security with the inclusion of a key-based hash.'






44. Key exchange for IPSEC






45. 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.






46. 'group 5 identifies a 1536-bit key - provides for highest security but is the slowest of all groups.'






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






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






49. Act of encapsulating a packet within another packet.






50. 'Created by NIST in 1994 - is the algorithm used for digital signatures but not for encryption.'