Explaining diffie hellman algorithm and rail fence cipher


Question1) A root digital certificate is typically issued by who?

1. Registration authority
2. Certificate authority
3. Any individual
4. X800 standards commitee
5. A secure directory system that uses LDAP

Question2) The number of different keys used in symmetric encryption is_________

Question3) Select the correct answer. The Diffie Hellman algorithm is used for what?

1. Public key encryption.
2. Symmetric encryption
3. Message Authentication
4. Key Exchange
5. Message digest generation

Question4) When creating a digital envelope which of the following steps are done.

A. The message is encrypted using a one time random symmetric key
B. The one time random symmetric key is encrypted by using the receivers private key
C. The one time random key is made a public key
D. The message is encrypted by using a one time random asymmetric key
E. The one time random symmetric key is encrypted with the receivers public key

1. A, E
2. A, C
3. B, E
4. C, D
5. A, D

Question5) Select the best answer that defines Security Risk

1. Threat of attack coupled with security breach
2. Threat of attack and vulnerability to attack
3. Vulnerability to attack coupled with an active attack
4. Threat of active and passive attack

Question6) Using a Playfair cipher what is the plaintext for the following ciphertext. RNNEQLDKPCNRMI The keyword you should use is "MONEY". You are being asked to decrypt this message.

Question7) With a symmetric block cipher the relationship with key size, security and performance is what?

A. The larger the key the more secure the algorithm
B. The larger the key size the slower encryption/decryption performance.
C. The larger the key the easier to perform cryptanalysis
D. The smaller the key the more secure the encryption/decryption
E. The larger the key the faster the encryption/decryption performance.

1. A, C
2. A, B
3. A, B, C
4. C, D
5. B, C

Question8) A Security Mechanism is an implementation of a specific program, process or device that is designed to detect, prevent, or recover from a security attack.

• True
• False

Question9) Match the cryptology mechanism with what type it is.

    DES                                                                        Answer
    AES                                                              A. Symmetric stream encryption
    Diffie Hellman                                                 B. Mode of operation                
    Cipher block chaining                                      C. Hashing algorithm                                                                        
    Cipher feedback                                              D. Key exchange
    RC4                                                               E. Symmetric block encryption
    Electronic codebook
    SHA1
    3DES
    MD5

Question10) A Security Service protects against specific threats according to the categorization of security threats in the X.503 architecture.

• True
• False

Question11) Assuming only asymmetric encryption is being used for communication between two parties. How many different keys are in play for sending one message from person A to person B? Assume person B reads the message.

1. 2
2. 1
3. Cannot determine
4. At least three

Question12)

Select the best answer. If the sender uses the recipients public key to encrypt a message what functionality is provided:

1) Message integrity
2) Message confidentiality
3) Message authentication
4) Message authentication and message confidentiality
5) none of the choices

Question13) Using a rail fence cipher with a depth of 3 encrypt the following message:

The party is at Fenway in October

Question14) The sender of the message in Digital signature encrypts the message digest using what?

1. The secret key.
2. Receivers public key.
3. Senders private key.
4. Symmetric key.
5. MAC value.

Question15) A digital certificate is what?

1. A notarized document certifying your identity.
2. A mail message sent with a Digital Signature from any third party that certifies the identity of a person or an entity.
3. Secret keys (among other information) used for symmetric encryption.
4. Public key (among other information) used for asymmetric encryption.
5. A mail message from a registration authority (RA).

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Data Structure & Algorithms: Explaining diffie hellman algorithm and rail fence cipher
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