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Book 3 SANS 301 Questions and Answers Fully Solved
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Exam of 10 pages for the course SANS at SANS (Book 3 SANS 301)
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Book 3 SANS 301Cryptography - answerart of private communication in a public environment
not that the definition does not contain the word "encryption"
some cryptographic methods simply hide the message; they don't encipher it in any way
plaintext - answerhuman readable- has not been encrypted.
encryption - answertransform readable to nonreadable.
decryption - answertransform nonreadable back to original readable.
Key - answera numeric value of a given length expressed in bits. The changing part of
the encryption algorithm that you must protect
Keyspace - answerthe range of values that can be used to construct a key given a
particular length.
algorithm - answerpublic knowledge set of rules behind cryptography
cryptanalysis - answerart and science of breaking cryptography
called cryptanalytic attack
Why do you provide cryptography? - answerconfidentiality - information kept private and
secure
integrity - data not modified, deleted or added
availability- systems available to whom requires them
authenticity- providing verification or identities
accountability- assurance by recording identities and activities
nonrepudiation - answerthe person that sent a message cannot deny doing so
steganography - answerthe art and science of hiding information by embedding
messages within other, seemingly harmless messages
today it's hiding messages inside a picture, movie, or similar type of file.
cryptography vs. steganography - answercryptography is scrambled
steganography- hidden
, steghide - answera tool to put text inside of a message
if the message is first encrypted, can it be discovered? - answerno
encryption vs. steganography - answerencryption- provides confidentiality of
communication. it does not provide for secrecy of communication like steganography
does.
using encryption itself- people cannot tell what you are saying but you can tell you are
talking privately.
transposition - answertransposes the order of letters (or of groups of letters or of whole
words in some cases).
it's a type of cryptography.
also known as obfuscation and permutation
Scytale - answerA tool used to perform a transposition cipher, consisting of a cylinder
with a strip of parchment wound around it on which is written a message
means staff in Greek.
another example of transposition
column shift - answeran example of transposition
substitution ciphers - answerreplace the letters of a message using some formula. some
replace letters with other letters.
some replace letters with numbers
monoalphabetic ciphers - answerworks by the simple expediency of replacing the
plaintext alphabet with a ciphertext alphabet. any number of methods for creating the
ciphertext alphabet are employed.
best example if Atbash/ would turn the alphabet backwards. instead of ABC it was ZYX.
Caesar Cipher - answera technique for encryption that shifts the alphabet by some
number of characters. rotates by 3 positions
alphabet is rotated...aka rotational substitution cipher.
ROT 13 - answerRotate all charachters 13 letters through the alphabet ( A becomes N,
B becomes O ... ) - Mono-Alphabet Substitution Cipher
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