Welcome to the Deciphering File Formats MCQs Page

Dive deep into the fascinating world of Deciphering File Formats with our comprehensive set of Multiple-Choice Questions (MCQs). This page is dedicated to exploring the fundamental concepts and intricacies of Deciphering File Formats, a crucial aspect of Reverse Engineering. In this section, you will encounter a diverse range of MCQs that cover various aspects of Deciphering File Formats, from the basic principles to advanced topics. Each question is thoughtfully crafted to challenge your knowledge and deepen your understanding of this critical subcategory within Reverse Engineering.

Check out the MCQs below to embark on an enriching journey through Deciphering File Formats. Test your knowledge, expand your horizons, and solidify your grasp on this vital area of Reverse Engineering.

Note: Each MCQ comes with multiple answer choices. Select the most appropriate option and test your understanding of Deciphering File Formats. You can click on an option to test your knowledge before viewing the solution for a MCQ. Happy learning!

Deciphering File Formats MCQs | Page 6 of 9

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Q51.

What is the purpose of cryptographic hashing algorithms?

To create long messages

To create a predetermined hash value

To identify specific messages

To write the hash value into a global variable

Discuss

Answer: (b).To create a predetermined hash value Explanation:Cryptographic hashing algorithms are used to create a predetermined hash value from a message.

Q52.

What are the two basic properties of cryptographic hashes?

The hash is extremely likely to produce the same hash value for different messages

It is extremely likely that there would ever be two different messages that produce the same hash

It is extremely unlikely to create a message that will generate a predetermined hash value

Both b and c

Discuss

Answer: (d).Both b and c Explanation:Two basic properties of cryptographic hashes are that it is extremely unlikely that there would ever be two different messages that produce the same hash and that it is virtually impossible to create a message that will generate a predetermined hash value.

Q53.

Which cryptographic hashing algorithm is used by Cryptex?

MD5

SHA-256

SHA-1

AES

Discuss

Answer: (a).MD5 Explanation:Cryptex is using the MD5 hashing algorithm to hash unknown, nontextual data, and writing the result into a global variable.

Q54.

What is the length of an SHA hash?

128 bits

160 bits

256 bits

512 bits

Discuss

Answer: (b).160 bits Explanation:An SHA hash is 160 bits long, as opposed to MD5 hashes which are 128 bits long.

Q55.

What is the purpose of the CryptDeriveKey API?

To generate cryptographic session keys derived from a base data value.

To calculate an additional MD5 hash from the SHA hash.

To encrypt and decrypt data using the same key.

To store the SHA hash directly in the file header.

Discuss

Answer: (a).To generate cryptographic session keys derived from a base data value. Explanation:The purpose of the CryptDeriveKey API is to generate cryptographic session keys derived from a base data value.

Q56.

Why does Cryptex calculate an additional MD5 hash from the SHA hash?

To detect whether the supplied password was correct or incorrect.

To store the SHA hash directly in the file header.

To encrypt and decrypt data using the same key.

To calculate the encryption key for 3DES algorithm.

Discuss

Answer: (a).To detect whether the supplied password was correct or incorrect. Explanation:Cryptex calculates an additional MD5 hash from the SHA hash to detect whether the supplied password was correct or incorrect.

Q57.

Why doesn't Cryptex store the SHA hash directly in the file header?

Because it is impossible to extract the original plaintext password from the SHA hash value.

Because it would make it incredibly easy to decrypt Cryptex archives.

Because someone would be able to covert the MD5 hash value to an equivalent SHA hash value.

Because it is virtually guaranteed to be mathematically impossible to obtain the original data from the MD5 hash value.

Discuss

Answer: (b).Because it would make it incredibly easy to decrypt Cryptex archives. Explanation:Cryptex doesn't store the SHA hash directly in the file header because it would make it incredibly easy to decrypt Cryptex archives.

Q58.

Why does Cryptex calculate the MD5 password-verification hash from the SHA hash value and not directly from the plaintext password?

Because it is impossible to obtain the original data from the MD5 hash value stored in the header.

Because someone would be able to covert the MD5 hash value to an equivalent SHA hash value.

Because the plaintext password might not be available at the time of verification.

Because it is virtually guaranteed to be mathematically impossible to obtain the original data from the SHA hash value.

Discuss

Answer: (b).Because someone would be able to covert the MD5 hash value to an equivalent SHA hash value. Explanation:Cryptex calculates the MD5 password-verification hash from the SHA hash value and not directly from the plaintext password because of the (admittedly remote) possibility that someone would be able to covert the MD5 hash value to an equivalent SHA hash value and effectively obtain the decryption key.

Q59.

What is the CryptDeriveKey API used for?

Generating cryptographic session keys derived from a base data value

Generating a 160-bit SHA hash calculated from the plaintext password

Storing the SHA hash in the file header

Detecting whether the supplied password was correct or incorrect

Discuss

Answer: (a).Generating cryptographic session keys derived from a base data value Explanation:According to Microsoft’s documentation, CryptDeriveKey “generates cryptographic session keys derived from a base data value.”

Q60.

Why does Cryptex calculate an additional hash (using the MD5 algorithm) from the SHA hash and store the result in the file header?

To use as a key for encrypting and decrypting the data

To store the unique password identification

To make it incredibly easy to decrypt Cryptex archives

To detect whether the supplied password was correct or incorrect

Discuss

Answer: (b).To store the unique password identification Explanation:When an archive is opened, the supplied password is hashed twice (once using SHA and once using MD5), and the MD5 result is compared against the one stored in the archive header. If they match, the password is correct. Cryptex calculates an additional hash from the SHA value and stores that as the unique password identification.

Page 6 of 9

Low Level Software 🔒

Windows Fundamentals 🔒

Reversing Tools 🔒

Auditing Program Binaries 🔒

Reversing Malware 🔒

Antireversing Techniques 🔒

Breaking Protections 🔒

Reversing .NET 🔒

Deciphering Code Structures 🔒

Deciphering Program Data 🔒

Welcome to the Deciphering File Formats MCQs Page

Deciphering File Formats MCQs | Page 6 of 9

Explore more Topics under Reverse Engineering

Introduction to Reverse Engineering

Beyond the Documentation

Piracy and Copy Protection

Decompilation

Understanding Compiled Arithmetic

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