SHA 3 algorithm introduction, diagram, design

Title: SHA-3 Algorithm
Presented by: soha khan

Cryptographic Hash Functions
It is an algorithm that takes an input (often called a
message) and returns a fixed-size string of bytes. The
output, typically a ‘digest’, is unique (in theory) to each
unique input. Even a tiny alteration to the input will
produce a completely different output.

Properties of Hash function
 Deterministic: For a given input, the output (hash) will always be
the same.
 Fast to compute: For any given data, the hash can be quickly
computed.
 Irreversible: It should be computationally difficult to regenerate the
original input value given the hash output.
 Collision-resistant: It should be computationally difficult to find two
different inputs that produce the same output.
 Avalanche effect: A tiny change in the input should produce such
a drastic change in output that the new hash appears uncorrelated
with the old hash.

Background History
 The SHA-3 algorithm is also known as the Keccak algorithm
 The development of SHA-3 began as a response to
vulnerabilities identified in earlier hash functions, including its
predecessors like SHA-1 and SHA-2. In 2007, the U.S. National
Institute of Standards and Technology (NIST) announced a
public competition to develop a new cryptographic hash function.
This competition drew a myriad of submissions from
cryptographers worldwide. In 2012, the Keccak algorithm was
selected as the winner, and by 2015, it was standardized and
named SHA-3.

History ( Keccak Team)
Bertone, Daemen, Peters, and Gill van was announced as the
SHA-3 winner on October 2, 2012.

SHA-3 Introduction
 SHA-3 (Secure Hash Algorithm 3) is the latest member of the
SHA family of standards, released by NIST on August 5, 2015.
 Unlike its predecessors (SHA-1 and SHA-2), SHA-3 uses the
sponge construction, specifically the Keccak-f permutation,
providing a different approach to processing data.
 SHA-3 supports variable output lengths of 224, 256, 384, or 512
bits, offering adaptability based on specific cryptographic
requirements.
 Designed to address potential weaknesses in earlier hash
functions, SHA-3 aims to provide a high level of security against
various types of cryptographic attacks.
 The hash value is typically represented in hexadecimal form. A
base-16 numerical system using digits 0-9 and letters A - F,
where each digit represents four binary digits (bits).

SHA 3 variants
You can select the desired SHA-3 variant based on the level
of security and length of the hash value you need for your
specific application.
1. SHA3-224: Produces a 224-bit hash value.

Design
 SHA-3 uses the sponge construction, in which data is "absorbed" into
the sponge, then the result is "squeezed" out. In the absorbing phase,
message blocks are XORed into a subset of the state, which is then
transformed as a whole using a permutation function f. In the "squeeze"
phase, output blocks are read from the same subset of the state,
alternated with the state transformation function f. The size of the part
of the state that is written and read is called the "rate" (denoted r), and
the size of the part that is untouched by input/output is called the
"capacity" (denoted c). The capacity determines the security of the
scheme. The maximum security level is half the capacity.
 Given an input bit string N, a padding function {pad}, a permutation
function f that operates on bit blocks of width b, a rate r, and an output
length d, we have capacity c= b-r and the sponge construction
Z =sponge [ f, pad, r ] (N, d), yielding a bit string Z of length d

Diagram
 The sponge construction for hash functions. Pi are input, Zi are hashed
output. The unused "capacity" c should be twice the desired resistance
to collision or preimage attacks.

SHA 3 algorithm introduction, diagram, design

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