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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. IPsec implements using a shim header between L2 and L3






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






3. 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.






4. Uses protocol number 50.






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






6. 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.






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






8. '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.'






9. 'Encryption - where Peer X uses Peer Y






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






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






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






13. IPSEC Encryption is performed by


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






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






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






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






18. Does not provide payload encryption.






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






20. Key exchange for IPSEC






21. One of the most popular tunneling protocols is






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






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






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






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






27. '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






28. The DES algorithm that performs 3 times sequentially.






29. Uses protocol number 51.






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






31. Act of encapsulating a packet within another packet.






32. DoS attacks are more probable with this mode.






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






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






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






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






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






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


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






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






41. '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.'






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






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






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






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






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






47. More CPU intensive






48. '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.'






49. Used in IPsec for two discreet purposes:






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