Chapter 8 1. Explain how cryptography and cryptanalysis provide a sophisticated
ID: 3754397 • Letter: C
Question
Chapter 8 1. Explain how cryptography and cryptanalysis provide a sophisticated approach to security 2. Explain how the science of encryption, known as cryptology encompasses cryptography and cryptanalysis. 3. Explain how today many common IT tools use embedded encryption technologies to protect sensitive information within applications. 4. Explain how a plaintext can be encrypted through one of two methods, the bit stream method or the block cipher method. 5. Explain how in a substitution cipher, you substitute one value for another. | 6. Describe a type of substitution based on a monoalphabetic 7. Explain that hash functions are mathematical algorithms used to 8. Describe how symmetric encryption uses the same key, also substitution only uses one alphabet. confirm the identity of a specific message and confirm that the content has not been changed. known as a secret key, to encrypt and decrypt a message. 9. Explain how symmetric encryption methods can be extremely efficient, requiring minimal processing to either encrypt or decrypt the message. 10. Explain how asymmetric encryption is a category of encryption techniques also known as public-key encryption.Explanation / Answer
ANSWRE NO 1:
a)Cryptography includes major techniques for security such as
a)microdots,
b) merging words with images,
c) and other ways to hide information in storage or transit.
b)Cryptography is also associated with Plain text (encryption) to cipher text(decryption) coversion for secured data.
Sophisticated security approaches:
a)Confidentiality (the information cannot be understood by anyone)
b)Integrity (the information cannot be altered in storage or transit)
c)Non-repudiation (the creator/sender of the information cannot deny ata later stage)
d) Authentication (the sender and receiver can confirm each others identity and the origin)
ANSWER NO:2
If one wants to keep information secret,there are two possible strategies:
a) hide the existence of the information,
b) make the information unintelligible.
Cryptography is the process of making art and science of keeping information secure from unintended audiences, of encrypting it.
Conversely, cryptanalysis is the art and science of breaking the encoded data.
cryptology is the branch of mathematics which encompassing both cryptography and cryptanalysis.
ANSWER NO:3
a)Today in modernising technology field,The web and many other IT needs uses modern communication systems where hybrid approach is needed.
b)As because public key encryption is not very computationally efficient compared to symmetric key encryption.
c)IT industry uses embedded encryption technologies.On the web, the relatively slower public key cryptography is used
initially to establish a secure connection between costumer and a website.
d)Then will use with a secure channel in place, the faster symmetric system can be used to share a key and then scramble the data passing back and forth.
e)End-to-end encryption helps in reducing this scrambling problem by having the message making software apply directly.
ANSWER NO:4
A bit stream cipher is a symmetric key cipher which helps to encrypt the plaintext which are combined with a pseudorandom cipher digit stream (keystream).
In a bit stream cipher, each plaintext digit is encrypted one at a time with the corresponding digit of the keystream, to give a digit of the ciphertext bitstream.
Since encryption of each plaintext stream digit is dependent on the present state of the cipher, it is also known as state cipher.
In practice, a digit is typically a bit and it is done by the combining operation of an exclusive-or (XOR).
ANSWER NO:5
a)A substitution cipher is a method of encrypting by which units of plaintext are replaced with ciphertext
b)The "units" may be single letters, pairs of letters, triplets of letters,values, mixtures of the above
c)The receiver deciphers the value by performing the reverse substitution cipher.
ANSWER NO:6
There are a number of different types of substitution cipher.They are
a)simple substitution cipher
b)monoalphabetic cipher
c)polyalphabetic cipher
Monoalphabetic cipher:Eg:california is the word to encrypt
Resulting sequence in monoalpahabetic where oly one alphabet changes:
ADQZCBPYFHUIGTLESNMXOJVRKW (21543786)
ANSWER NO:7
a)A hashing function are mathematical algorithms used to identify the goal to generate a safe hash
b)Hash is a value computed from a base input number to confirm and using a hashing function.
c)The hash value is a summary of the original data.
d)It is impossible to restore the original input without knowing what was the starting data.
e)This is how it confirms that the content cannot be changed
ANSWER NO:8
a)Symmetric-key encryption ueses the same key as security key are algorithms for cryptography that use the same cryptographic keys
for both encryption of plaintext and decryption of ciphertext.The keys may be identical or there may be a simple transformation to go between the two keys.
b)The keys,represent a shared secret between two or more parties that can be used to maintain a private information link.
c)This requirement that both parties have access to the secret key is the diadvantage that, in comparison to public-key encryption
(also known as asymmetric key encryption).
ANSWER NO:9
a)Size of cryptogram: symmetric encryption does not increase the size of the cryptogram (asymptotically).so it requires minimal processing for both encryption and decryption
b)Performance on a modern CPU with hardware AES support, encryption or decryption speed is over 2000 megabyte/second (per core) which is highly efficient
c)Symmetric encryption is generally
a)faster than asymmetric encryption
b)encryption can be done with larger amounts of data.
c)The time difference will increase linearly as the amount of data
ANSWER NO:10
a)Asymmetric encryption, is the cryptographic system that uses pairs of keys:
a)public keys which may be disseminated widely,
b)and private keys which are known only to the owner.
This accomplishes two functions:
a)authentication, where the public key verifies that a holder of the paired private key sent the message, and
b)encryption, where only the paired private key holder can decrypt the message encrypted with the public key.
Hence it accompolishes public key functions it is known as public key cryptography and it is one of the encryption techniques.
Hope this helps you.All the best
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