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






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






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






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

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5. '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






6. '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






7. Uses protocol number 50.






8. More CPU intensive






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






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






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






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






13. 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.






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






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






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






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






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






19. '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.'






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






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






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






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






24. Provides authentication and encryption of the payload.






25. 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.






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

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27. One of the most popular tunneling protocols is






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






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






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






31. 'MACs with hash algorithms -'






32. A






33. Uses protocol number 51.






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






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






36. '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.'






37. DoS attacks are more probable with this mode.






38. '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.'






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






40. Act of encapsulating a packet within another packet.






41. 'Encryption - where Peer X uses Peer Y






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






43. '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.'






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






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






46. The DES algorithm that performs 3 times sequentially.






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






48. IPSEC Encryption is performed by

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






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