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






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






3. Used in IPsec for two discreet purposes:






4. Uses protocol number 50.






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






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






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






8. 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.






9. Used in government installs and was created to work with the SHA-1 hash algorithm.






10. 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.






11. Integrity checks are done

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






13. Verify whether the data has been altered.






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






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






16. 'Encryption - where Peer X uses Peer Y






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






18. Uses IKE for key exchange.






19. 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.






20. '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.'






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






22. 'provides everything required to securely connect over a public media - such as the Internet.'






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






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






25. One of the most popular tunneling protocols is






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






27. '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






28. '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.'






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






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






31. Common key size is 1024 bits.






32. 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.






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

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






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






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






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






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






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






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






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






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






44. More CPU intensive






45. A






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






47. The DES algorithm that performs 3 times sequentially.






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






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






50. Key exchange for IPSEC