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






2. 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.






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






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






5. '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.'






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






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






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






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

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10. Uses IKE for key exchange.






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






12. Verify whether the data has been altered.






13. DoS attacks are more probable with this mode.






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






15. ID exchange and authentication of D-H key by using the reply to the received nonce or string of bits

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16. 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.






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






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






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






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






21. A






22. 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.






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






24. Common key size is 1024 bits.






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






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






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






28. 'Developed in 1977 by Ronald Rivest - Adi Shamir - and Leonard Adleman (therefore - RSA).'






29. IPsec implements using a shim header between L2 and L3






30. Invented by Ron Rivest of RSA Security (RFC 1321).






31. '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






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






33. 'It is not used for encryption or digital signatures; it is used to obtain a shared secret






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






35. '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.'






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






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






38. Used in IPsec for two discreet purposes:






39. '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






40. Key exchange for IPSEC






41. Uses protocol number 50.






42. IPSEC Encryption is performed by

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43. Provides authentication and encryption of the payload.






44. 'MACs with hash algorithms -'






45. '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.'






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






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






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






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






50. '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.'