Chapter 6: Hashing and Digital Signature Flashcards
is a security method that scrambles a message into a fixed length string without the possibility of turning it back to its original form.
Hash(ing) or Message Digest
is also a basic component of digital signature.
Hash
is a one-way function that takes a message of arbitrary length as input and produces fixed-length bit string as output.
Hash Function
is the possibility of two different messages that would result to the same hash value.
Collision
is a concept under Probability theorem, that states that in a set of randomly chosen people, some pair of them will have the same birthday.
Birthday Paradox
this principle state that if a number of items are put into a set of containers, then at least one container will contain more than one item.
Pigeon Hole Principle
is a mathematical algorithm that maps data of arbitrary size (message) to a bit array of a fixed size.
Cryptographic Hash Function (CHF)
[3] Common Examples of Hash Algorithm
- Message Digest Algorithm (MD5)
- Secured Hash Algorithm 1 (SHA 1)
- Secured Hash Algorithm 2 (SHA 2
a hash function that produces 128-bit hash value for arbitrary length.
Message Digest Algorithm (MD5)
designed the Message Digest Algorithm.
Ronald Rivest (1991)
a cryptographic hash function which takes an input and produces 160-bit(20-byte) hash.
Secured Hash Algorithm 1 (SHA 1)
is a family that consists of six hash function with digests that are 224, 256, 384, or 512 bits.
Secured Hash Algorithm 2 (SHA 2)
[3] Application of Hash Functions
- Password Protection
- Checksum / Integrity Check
- Digital Signature
Desirable Properties of Hash Algorithm
- Randomness
- Avalanche Effect
- Strict Avalanche Criterion
[3] Tests perform to evaluate randomness
o Correlation Test
o Run Test
o Compute for the Mean and Variance and Independence of Probability
[2] Tests performed to evaluate Avalanche Effect
o Confusion Test
o Diffusion Test
test the effect of the key to the ciphertext.
Confusion Test
test the effect of the plaintext to the ciphertext.
Diffusion Test
at least 50%-bit flip in the ciphertext per one bit flip in the input.
Strict Avalanche Criterion
has the same authentication and legally binding function as handwritten signature.
Digital Signature
[3] Advantages of Digital Signature
- Authenticity (signed by real signatory)
- Integrity (document is not altered)
- Non-Repudiation
[3] Major Components of a Digital Signature
- Digital Document / File
- Hash Algorithm
- Encryption Algorithm
the file that is needed to be digitally signed.
Digital Document / File
this is to ensure that the document is not altered.
Hash Algorithm -
