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






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


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






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






5. Used in IPsec for two discreet purposes:






6. 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.






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






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






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






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






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






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






13. '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.'






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






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






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






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






18. IPSEC Encryption is performed by


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






20. 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.






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






22. Integrity checks are done


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






24. Verify whether the data has been altered.






25. More CPU intensive






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






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






28. One of the most popular tunneling protocols is






29. '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.'






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






31. '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.'






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






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






34. The DES algorithm that performs 3 times sequentially.






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






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


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






38. '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






39. 'Encryption - where Peer X uses Peer Y






40. '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.'






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






42. 'in most cases - this mode is preferred with certificates.'






43. '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.'






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






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






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






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






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






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