Question

Calcula las edades de dos hermanos, sabiendo que la suma de las dos edades es 15 y que el doble de la del mas pequeño mas cinco veces la del mayor es igual a 13.

Answer 1

) Observe traffic on a network can be a safety violaci'on 2. (F) not disclose t'ecnicas used in a security service can achieve higher levels of security 3. (V) Altering the identificaci'on sender of a message without changing the content is an attack on the integrity 4. (F) the non-repudiation service requires confidentiality 5. (F) the service involves negaci'on violaci'on of confidentiality 6. (V ) AES is M'as r'apido RSA 7. (V) the criptoan'alisis to discover possible faults of a criptogr'afico algorithm 8. (V) Encryption is computationally secure if the cost exceeds value break informaci'on 9. (V) If you have a m'aquina capable of performing 1 mill'on decrypted per second, and 20-bit keys are used, demorar'ıa less than two seconds in decrypted un 10. (V) DES message is 'a based on the Feistel structure 11. (V) accepts keys M'as AES 128 bit 12. (F) the block cipher is secure M'as the stream cipher 13. (F) the key sesi'on should be chosen by one of the entities that wish to communicate 14. (V) autenticaci'on service alteraci'on implies that a message is detected 15. (V) can be used to autenticaci'on 16 Blowfish. (F) you can find a summary funci'on criptogr'afico with fixed output property (and finite) do not have collisions size 17. (F) If a secret value is concatenated (I s'olo known transmitter and receiver) to the original message, then it calculates the criptogr'afico summarized and env'ıa, can ensure the integrity 18. (F) to verify the integrity of a message, the receiver calculates the inverse of the summary criptogr' AFICO included in the message 19. (V) MD5 accepts inputs of any size 20. (V) in the attacks on criptogr'afico digest algorithms, so-called colisi'on itself, the attacker simply look for two values ​​m and m 'collide, but both their values ​​known as the summary criptogr'afico 21. (F) HMAC uses criptograf'ıa asim'etrica 22. (V) RSA allows messages encrypted with the key are p'ublica it decrypted with the secret key, and vice versa, that encrypted with the secret can be decrypted with p'ublica 23. (F) the strength of the Diffie-Hellman algorithms is based on the difficulty of the factorization n'umeros discrete 24. (F) over RSA keys 128 bits are now considered safe 1 25. (V) X.509 certificates allow to avoid attacks "man in the middle" in p'ublica criptograf'ıa 26. (V) If a has a certificate signed by the certifying authority AC1 (AC1 << a >>), the B signs it AC2 (AC2 << B >>), and are certified AC3 >> << AC1 and AC2 AC3 <<> >, then A and B can communicate securely using encryption asim'etrico 27. (V) the IPSec protocol allows applications using secure channels without having to be modified or recompiled 28. (V) autentitaci'on service ( AH) IPSec transport mode protects against alterations IP address of the original packet 29. (V) the protocol ISAKMP (Internet Security Association and key Management protocol) allows you to set IPSec encryption keys 30. (F) TLS (transport Layer Security ) allows applications using secure channels without having to be modified or recompiled 31. (F) the SSL Record protocol allows, among others, par'ametros negotiate encryption and autenticaci'on 32. (V) PGP compresses before 33. encrypt (V) keychains system PGP allows a user to have several secret keys 34. (F) currently, in UNIX systems access keys (passwords) is stored encrypted using a secret key to a file system in the / etc / shadow 35. (F) the directory inform'aticos viruses replicate without an anfitri' program