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






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






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






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






5. 'MACs with hash algorithms -'






6. '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.'






7. Act of encapsulating a packet within another packet.






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






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

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






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






12. '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.'






13. Key exchange for IPSEC






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






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






16. '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






17. 'Three keys encrypt the data - which results in a 168-bit encryption key. The sending device encrypts the data with the first 56-bit key.'






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






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






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






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






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






23. Used in IPsec for two discreet purposes:






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






25. Provides authentication and encryption of the payload.






26. DoS attacks are more probable with this mode.






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






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






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. '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.'






31. 'group 2 identifies a 1024-bit key - group 2 is more secure - but slower to execute.'






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






33. 'has a Next Protocol field which identifies the next Layer 4 transport protocol in use - TCP or UDP'






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






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






36. 'When using the hash-based key function -'






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






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






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






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






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






42. Uses protocol number 51.






43. Can be implemented efficiently on a wide range of processors and in hardware.






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






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






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






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






48. '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






49. Negotiation of a shared secret key for encryption of the IKE session using the D-H algorithm

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