Discussion on Hashing and Message Digest
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HashingandMessageDigest.pptxFundamentals of Cryptography Week 6
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Agenda
Week 6 Overview
Reading
Lecture
Discussion Question
Hashing and Message Digests
Week 7 Pre-view
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Week 6 Overview
Reading – Chapter 5 – Hashing and Message Digests (Course Text)
Lecture – You are watching/listening to it now!
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Discussion Question 5
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Peer Response(s): Peer Response(s) are due by Sunday (11:59:59pm ET)
Primary Task Response:
Please provide a detailed response to the below to include specific details and examples.
Primary Response: Primary Discussion Response is due by Wednesday (11:59:59pm Eastern Time Zone (ET))
Hashing & Message Digests
Hashing should not be confused with the previous forms of encryption that we have discussed. Although they share similarities, there are many differences. Please discuss both the similarities and differences between the previous encryption methods we have discussed and hashing. In addition, what is a message digest and what would we use it for?
Discussion Question 5
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- Read the responses from your peers and offer a constructive critique or additional information that adds substantively to the discussions.
Peer Response
- Remember, a response that simply states that their post was good or that you liked it is not considered substantive.
- You should contribute to the learning via your posts and responses.
- Be sure to acknowledge any outside sources you use.
Categories of Cryptosystems
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Organization of Cryptosystems
Two-Way Cryptography
Symmetric
Asymmetric
Steganography
Message Integrity Controls
Stream
Block
Factoring the Product of Large Primes
Discreet Logarithms
Message Integrity Controls (MIC)
MICs detect alterations (whether intentional or accidental) to a message during transmission
A MIC is a special value that is calculated based on the message contents and added to the message to be sent
Intentional Change
Accidental Change
CBC-MAC
Digital Signature
HMAC
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Hash Function Characteristics
Produces a “condensed representation” of the original message
Should be a one-way function
Non-linear relationship between hashes
Should derive the hash using the whole, original message
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Common Hash Functions
Message Digest 2, 4, 5, 6
Secure Hash Algorithm (SHA) 1, 2, 3
HAVAL
RIPEMD
Tiger
WHIRLPOOL
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Digital Signatures
What are digital signatures?
Message
Message
Alice
Bob
Hash
Digest
Digest
Digest
Digital
Signature
Hash
Verified
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Message
Message
Digital
Signature
Alice’s Private Key
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Uses of Digital Signatures
E-commerce
Non-repudiation of origin
Integrity of message
Software distribution
Trusted time stamp
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Example of a Complex Hybrid System
E
E
D
D
Alice
Bob
E
Alice’s Private Key
D
Alice’s Public Key
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H
D
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Digest
Digest
Digest
Digest
Digest
Bob’s Public Key
Bob’s Private Key
Digital Signature
Message
Message
Bob’s Public Key
Bob’s Private Key
CT(k)
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Summary
Fundamentals of Hashing
Hashing is known as one-way encryption
Hashing produces a message digest or hash
Hashing produces a fixed-length output no matter the length or size of the input
Purpose of Hashing
Hashing is designed to verify the integrity of a message
Hashing can assist a receiving party detect changes in a document or other piece of information that may otherwise remain unknown
Hashing is not a way to preserve the confidentiality of a message
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Summary
Applications of Hashing
Hashing is used in digital signatures
Hashing is used to verify the status of certain files, such as key system files or other data
Hashing is used to verify items, such as the status of antivirus updates or other types of files
Types of Hashing Algorithms
Hashing algorithms are known to the public and can be scrutinized
Hashing algorithms are used to determine how the creation and evolution of a has will be done
Algorithms that are in use today include SHA, MD5, and others
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Summary
Key Concepts of Hashing
Hashing algorithms will always generate the same length message digest for every input
Hash algorithms are embedded in many software applications
Hashing is designed to create powerful non-reversible digests
Key Terms and Terminology
Hashes are the output of a hashing algorithm
Hashes are sometimes also known as message digests
Collisions refer to two or more different inputs that generate the same output
High numbers of collisions indicate a weak or poorly written algorithm
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Week 7 Overview
Reading – Read/review/memorize the cryptography terminology flash cards.
Lecture
Week 7 Assignment
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Questions?
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Symmetric Key
Symmetric Key
