SHA 256 | SHA 256 Algorithm Explanation | How SHA 256 Algorithm Works | Cryptography | Simplilearn

Summary

This video delves into Secure Hash Algorithms (SHA), crucial for secure communication in the digital age. It explains hashing's role in scrambling data irreversibly and the SHA family's evolution from SHA-0 to SHA-3. The script outlines how hashing secures passwords, verifies data integrity, and is integral to digital signatures and SSL handshakes. It also details the SHA algorithm's process, from padding messages to generating digests, emphasizing its security against brute force attacks.

Takeaways

• 📝 Hashing is the process of transforming data into a scrambled format using algorithms to ensure data security.
• 💲 The primary difference between hashing and encryption is that hashing is irreversible, meaning the original data cannot be retrieved from the hash.
• 💵 Hash functions like SHA are crucial for secure communication and data transmission, playing a significant role in modern technology.
• 💲 Websites commonly use hashing to store user passwords securely, preventing plain text passwords from being exposed.
• 💵 Hashing verifies data integrity by comparing hash values before and after data transmission, ensuring the data has not been altered.
• 💲 The SHA (Secure Hash Algorithm) family, developed by NIST and NSA, includes SHA-0, SHA-1, SHA-2, and SHA-3, each with varying bit lengths and security features.
• 💵 SHA-256 and SHA-512 are part of the SHA-2 family, with SHA-256 using 32-bit words and SHA-512 using 64-bit words, offering different levels of security.
• 💲 SHA-3 was chosen after a public competition and differs significantly in structure from the other SHA family members, providing enhanced security.
• 💵 The SHA algorithm involves several steps including padding the message, initializing variables, processing blocks, and iterating through rounds to produce a hash digest.
• 💲 Hash functions are designed to be irreversible and resistant to collisions, making them essential for secure storage and transmission of sensitive data.

Q & A

What is the primary purpose of hashing?

The primary purpose of hashing is to scramble a piece of information or data beyond recognition using hash functions, which are algorithms that perform mathematical operations on the original plain text.

How does hashing differ from encryption?

Hashing differs from encryption in that hashes are irreversible; no decryption key can convert a digest back to its original plain text value.

What is the Secure Hash Algorithm (SHA) family?

The Secure Hash Algorithm family is a set of cryptographic hash functions published by the National Institute of Standards and Technology along with the NSA.

What are the different families of hash functions within the SHA family?

The SHA family includes SHA-0 (160-bit), SHA-1 (160-bit), SHA-2 (with functions like SHA-256 and SHA-512), and SHA-3 (also known as Keccak).

How does the SHA algorithm ensure data integrity?

SHA algorithms ensure data integrity by generating a fixed-size hash value (digest) from variable-sized data, which can be compared before and after data transit to verify that the data has not been corrupted.

Why is hashing used for storing passwords?

Hashing is used for storing passwords to prevent plain text passwords from being stored on servers, thereby enhancing security and protecting user privacy in the event of a data breach.

What is the significance of the padding process in the SHA algorithm?

The padding process in the SHA algorithm ensures that the plain text message is compatible with the hash function by making the total number of bits a multiple of 512, which is necessary for the hashing process.

How does the SHA algorithm handle different lengths of plain text?

The SHA algorithm handles different lengths of plain text by padding the message to ensure the total number of bits is a multiple of 512, and then processing the message in 512-bit blocks.

What are the characteristics that SHA family functions must follow while generating a digest?

SHA family functions must ensure that the digest appears random, is irreversible, and that even a slight change in the plaintext triggers a drastic difference in the digest to prevent hash collisions.

How does the SHA algorithm contribute to secure web browsing sessions?

The SHA algorithm contributes to secure web browsing sessions by being part of the SSL handshake process, which involves agreeing on encryption keys and hashing authentication to prepare a secure connection between web browsers and servers.

What are the advantages of using SHA hash algorithms over storing data in plain text?

Using SHA hash algorithms over plain text storage provides advantages such as enhanced security through irreversible hash values, protection against data tampering, and the ability to verify the authenticity of digital signatures.

Outlines

00:00

🔒 Introduction to Hashing and SHA Algorithms

This paragraph introduces the concept of hashing, explaining it as a process to scramble data using hash functions, which are algorithms that perform mathematical operations on plain text to generate a hash value or digest. It differentiates hashing from encryption by emphasizing the irreversibility of hashes. The paragraph also covers the application of hashing in password storage and data integrity verification. It introduces the Secure Hash Algorithms (SHA) family, which includes SHA-0, SHA-1, SHA-2, and SHA-3, and their origins from the National Institute of Standards and Technology (NIST) and the NSA. The paragraph sets the stage for a deeper exploration of hashing and the SHA algorithms.

05:02

🔧 How SHA Hash Functions Work

This paragraph delves into the mechanics of the SHA hash functions, detailing the process of creating a hash digest from plain text. It explains how the input message is prepared by padding bits to make it compatible with the hash function, ensuring the length is a multiple of 512 bits. The paragraph outlines the initialization of chaining variables and the processing of message blocks into 512-bit chunks, which are then further divided into 16 sub-blocks. It describes the four rounds of operations performed on each sub-block, involving 80 iterations with the use of a constant array and a non-linear function. The paragraph also touches on the importance of digest length and the characteristics that a cryptographically secure hash function should possess, such as producing random-looking digests and preventing hash collisions.

10:05

🛡️ Benefits and Applications of SHA Hashing

The final paragraph highlights the advantages of using the SHA hash algorithm. It discusses how hashes are used in digital signatures for document verification, the secure storage of passwords to prevent unauthorized access, and the SSL handshake process for secure web browsing. The paragraph also mentions the role of hash functions in detecting file corruption by comparing hash values before and after data transmission. It concludes by emphasizing the reliability of hash functions to consistently produce the same output for the same input, which aids in ensuring data integrity and security.

Keywords

💡Hashing

Hashing is a process that transforms data into a fixed-size string of characters, which is typically a digest or hash value. In the context of the video, hashing is used to secure data by making it irreversible, ensuring that once data is hashed, it cannot be easily converted back to its original form. This is crucial for applications like password storage, where the original password should not be retrievable from the stored hash.

💡Secure Hash Algorithms (SHA)

The Secure Hash Algorithms (SHA) are a family of cryptographic hash functions published by the National Institute of Standards and Technology (NIST) and NSA. They are designed to take an input (or 'message') and return a fixed-size string of bytes. The video explains that SHA algorithms are used to ensure the security and integrity of data, with different versions like SHA-1, SHA-256, and SHA-512 catering to various security needs.

💡Cryptographic Hash Function

A cryptographic hash function is a special kind of hash function that is designed to be a one-way function, meaning it is infeasible to reverse it. The video emphasizes the importance of cryptographic hash functions in creating secure channels for data transmission, where the hash value appears random and any change in the input data results in a significantly different hash value.

💡Data Integrity

Data integrity refers to the accuracy and consistency of data over its entire life cycle. In the video, hashing is used to verify data integrity by comparing hash values before and after data transmission. If the hash values match, it confirms that the data has not been altered or corrupted during transit.

💡Password Storage

Password storage is a critical aspect of cybersecurity. The script explains how websites use hashing to store user passwords securely. When a user creates an account, their password is hashed and the hash is stored, not the password itself. This protects user privacy and prevents unauthorized access to plain text passwords.

💡Hash Collision

A hash collision occurs when two different inputs produce the same hash output. The video highlights the importance of avoiding hash collisions in cryptographic hash functions, as they can be exploited by attackers. SHA algorithms are designed to minimize the likelihood of collisions to maintain security.

💡Digital Signatures

Digital signatures are a security measure used to verify the authenticity of a document or file. The video mentions that hash algorithms like SHA-256 and SHA-512 play a significant role in creating digital signatures, which use asymmetric encryption to ensure that the document or file has not been tampered with.

💡SSL Handshake

The SSL handshake is a process that establishes a secure connection between a web server and a client, such as a web browser. The video explains that SHA functions are used during the SSL handshake to authenticate and agree on encryption keys, ensuring the confidentiality of data transmitted over the internet.

💡Non-linear Process

A non-linear process in the context of the SHA algorithm refers to the complex mathematical operations that are used to transform the data during the hashing process. The video describes how these operations, which vary with each round of processing, contribute to the security of the hash function by making it resistant to brute force attacks.

💡Padding

Padding is a technique used in the hashing process to ensure that the input data is of the correct length required by the hash function. The video script explains how padding is applied to the data before it is processed by the SHA algorithm, making it a crucial step in preparing the data for hashing.

💡Cryptographically Secure

Cryptographically secure refers to the property of a cryptographic system that makes it very difficult for an attacker to break. The video emphasizes that SHA hash functions are designed to be cryptographically secure by meeting requirements such as being irreversible and resistant to hash collisions.

Highlights

Technology dependency has increased due to advancements in communication and data transmission security.

Cryptography, encryption, and algorithms like DSA, RSA, AES are essential for secure communication.

Today's focus is on the Secure Hash Algorithms (SHA) family, the most advanced hash functions.

Hashing is the process of scrambling data beyond recognition using hash functions.

Hash functions generate a fixed-size string (hash value) from input data, which is irreversible.

Hashing is used for password storage and integrated verification to enhance security.

Websites use hashing to store user passwords securely without plaintext storage.

Hashing ensures data integrity by allowing verification of file contents during transit.

The SHA algorithm is a cryptographic hash function published by NIST and NSA.

SHA has four families: SHA-0, SHA-1, the SHA-2 family (SHA-256 and SHA-512), and SHA-3.

SHA-1 is a 160-bit hash function resembling the MD5 algorithm, designed for digital signatures.

SHA-2 uses different word sizes with SHA-256 using 32-bit words and SHA-512 using 64-bit words.

SHA-3, also known as Keccak, was chosen after a public competition and differs structurally from other SHAs.

Hash functions aim to produce random-looking digests and meet two main security requirements.

The SHA family has characteristics like fixed input text length and irreversible digests.

The SHA algorithm involves multiple steps including padding, initializing variables, and processing blocks.

The process includes 80 rounds of operations using a non-linear function and constant array.

The advantages of SHA include secure password storage, SSL handshake support, and file integrity checks.

SHA ensures data hasn't been tampered with, maintaining the same output for the same input.

Transcripts

we use our wi-fi every day for work and

we use the internet for entertainment

and communication

the dependency on technology is at an

all-time high thanks to the radical

developments and innovation in these

last two decades

a big portion of this belongs to

ensuring secure channels of

communication and data transmission

we have already covered videos on

cryptography encryption and other

algorithms such as the dsa rsa aes etc

today we will be covering the most

advanced hash functions known today

the secure hash algorithms family or sha

let's take a look at the topics to be

covered in today's video

we take a look at what is hashing and

its principles examples and applications

we learn about the origin of the sha

algorithm along with its methodology

there are some distinct characteristics

of the sha family that we cover as well

we take a look at the steps needed to

create hashed values using the sha

algorithm and then finally learn about

the prospective advantages for the same

let's first get acquainted with the

concept of hashing and its applications

hashing is the process of scrambling a

piece of information or data beyond

recognition

we can achieve this using hash functions

which are essentially algorithms that

perform mathematical operations on the

main plain text

the value generated after passing the

plain text information through the hash

function is called as the hash value

digest or in general just hash of the

original data

while this may sound similar to

encryption the major difference is that

hashes are made to be irreversible

no decryption key can convert a digest

back to its original plain text value

however a few hashing algorithms have

been broken down due to the increase in

computational complexity of the new

generation computers and processors

there are new algorithms that still

stand the test of time and are being

used among multiple areas for password

storage integrated verification etc

like we discussed earlier websites use

hashing to store user passwords so how

do they make use of these hashed

passwords

when a user signs up to a new account

the password is then run through the

hash function and the resulting digest

is stored on the servers

so the next time a user logs into the

account the same password he enters is

passed through the hash function again

if the digest matches with the one

stored on the server then he is allowed

to login to the account

this way no plain text password gets

stored preventing both the owner from

snooping on user data and protecting the

user privacy in the unfortunate event of

a data breach or a hack

we also use hashing when it comes to

verifying data integrity

when a user uploads a file onto the

internet he or she can pass the file

through a hash function and upload its

digest as well

when a new user downloads the file for

personal use they can again pass the

file through the same hash function

the digest values are then compared

within the newly generated value and the

value uploaded by the user

if the values match then the data

integrity is verified and the value was

not corrupted in transit

to generate these hash digests from a

standard input we use hash functions

such an example of a hash function is

the sha algorithm

let us learn more about it in our main

focus for the thing

the secure hash algorithm are a family

of cryptographic hash functions that are

published by the national institute of

standards and technology along with the

nsa

it was passed as a federal information

processing standard also known as fips

it has four different families of hash

functions

ssj0 is a 160 bit hash function

published in 1993 and it was closed down

later after an undisclosed significant

flaw

sha-1 is also a 160-bit hash function

which resembles the earlier md5

algorithm this was designed by the nsa

to be a part of the digital signature

algorithm

sga2 is a family of two similar hash

functions with different block sizes

known as the sha-256 and the sha-512

they differ in the word size

ssh-256 uses 32-bit words while sha-512

uses 64-bit words

sha-3 is a hash function properly known

as kcac it was chosen in 2012 after a

public competition among non-nsa

designers

it supports the same hash lengths as

hsj2 and its internal structure differs

significantly from the rest of the sha

family

as we have already iterated the process

is straightforward we pass a plain text

message to the sha hash function which

in turn performs certain mathematical

operations on the clear text to scramble

the data

the 160 bit digest received from this is

going to be radically different from the

plain text

the goal of any hash function is to

produce digests that appear to be random

to be considered cryptographically

secure the hash function should meet two

requirements

first that it is impossible for an

attacker to generate a message that

matches a specific hash value

and second it should be impossible for

an attacker to create two messages

producing the exactly same hash value

even a slight change in the plaintext

should trigger a drastic difference in

the two digest

this goes a long way in preventing hash

collisions which takes place when two

different plane tests have the same

digest

the sha family functions have some

characteristics that they need to follow

while generating the digest

let's go through a few of them

the length of the clear text should be

less than 2 to the power 64 bits in the

case of sha 1 and s h 256

this is essential to keep the plain text

compatible with the hash function and

the size needs to be in comparison area

to keep the digest as random as possible

the length of the hash digest should be

256 bits in the sha-256 algorithm 512

bits in the sha 512 algorithm and so on

bigger digest usually suggests

significantly more calculations at the

cost of speed and space

we typically go for the longest digest

to bolster security but there must be a

definite balance between the speed and

security of a hash function

by design all hash functions of the sha

512 she-256

are irreversible

you should neither get a plain text when

you have the digest beforehand

nor should the digest provide the

original value when you pass it through

the same hash function again

another case of protection is that when

the hash digest is passed into the sha

function for a second time we should get

a completely different digest from the

first instance

this is done to reduce the chance of

brute force attacks

to achieve this level of intricacy there

are a number of steps to be followed

before we receive the digest

let us take a look at the detailed

procedure as to how the sha algorithm

works

the first step is to make the plain text

compatible with the hash function

to do this we need to pad the bits in

the message

when you receive the input string you

have to make sure the size is 64 bit

short of a multiple of 512.

when it comes to padding the bits you

must add one first followed by the

remaining zeros to round out the extra

characters

this prepares our string to have a

length just 64 bits less than any

multiple of 512

here on out we can proceed to the next

step where we have to pad the length

bits

initially in the first step we appended

the message in such a way that the total

number of bits in the message was 64 bit

short from becoming a multiple of 512.

now we add the length of bits in such a

way that the total number of bits in the

message is a perfect multiple of 512

that means 64 bits plus the length of

the original message becomes a multiple

of 512. this becomes a final string that

needs to be hashed

in the next step we have to initialize

this chaining variables

the entire plain text message can now be

broken down into blocks of 512 bits each

unlike other hash algorithms like md5

which use 4 registers or buffers sha

family use 5 buffers of 32 bits each

they are named a b c d and e these

registers go through multiple rounds of

operation but the first iteration has

fixed hexadecimal values as can be seen

in the screen

moving on we have to process each of the

512-bit blocks by breaking each of them

into 16 sub-blocks of 32 bits each

each of them goes through four rounds of

operation that use the entire register

and have the 512-bit block along with

the constant array out of those four

rounds each round has 20 iterations so

in general we have 80 rounds sum total

the constant value of k is an array of

80 elements

of those 80 16 elements are being used

each round so that comes out to 80

rounds for each of those elements

the value of t differs by the number of

rounds as can be seen in the table below

a single formula is necessary to

calculate the output of each round and

iteration

the formula can be b c d e register is

equal to e plus a non-linear process b

along with a circular shift of a plus wt

plus kt

in this formula abcd is the register

value of the chaining variables as we

discussed before

p is the logical process which has a

different formula for each round

s5 is a circular shift by 5 bits

and wt is a 32-bit string derived from

the existing sub-block

this can be calculated depending on the

iteration at hand

kt signifies a single element of the 80

character element array which changes

depending on the particular round at

hand

for the values of wt the first 16 values

are the same as that of the sub blocks

so there is no extra calculation needed

for the next 64 elements the value of wt

can be calculated as shown in the

formula here to better understand this

let's take a look at how each of this

goes in a sequential process we have our

initial register using the 5 words of 32

bits each in the first step we put the

values of a b c and d to the subsequent

register as the output

next we use a non-linear process p that

changes depending on the round and uses

the values of b c and d as input

whatever output is generated from the

non-linear process it is added with the

value of the e register

next the value of a is circular shifted

by 5 bits and is added with the output

generated in the previous step

the next step is adding the value of wt

and the constant element of kt the

current output is then stored in the

register a similarly this iteration is

repeated every round and for each sub

block in the process once all the

registers are complete and all the sub

blocks are joined together to form the

single ciphertext message we will have

our hashed output regarding the

non-linear process p that uses the

values of b c and d as input the formula

changes every round to maintain a

complexity of the program that can

withstand brute force attacks

depending on the round the values are

passed through a logical operation which

is then added with the values of wt kt

and so on

now that we understand how to get our

hash digest from the plain text let us

learn about the advantages we obtain

when using the sha hash algorithm

instead of relying on data in a plain

text format

digital signatures follow asymmetric

encryption methodology to verify the

authenticity of a document or a file

hash algorithms like ssh 256 and the

industry standard sha 512 go a long way

in ensuring the verification of

signatures

passwords need not be stored in a plain

text format which makes them accessible

to hackers and other malicious actors

when using digest the database security

also gets a boost since the size of all

hash values will be the same

in the event of a hack or a breach the

malicious actor will only receive the

hash values with no way to regenerate

the plain text

in this case the plain text would be

user credentials

since the hash functions are

irreversible by design it has become a

compulsion when storing passwords on the

servers

the ssl handshake is a crucial segment

of the web browsing sessions and it's

done using sha functions

it consists of your web browsers and the

web servers agreeing on encryption keys

and hashing authentication to prepare a

secure connection

it relies on a combination of symmetric

and asymmetric algorithms which ensure

the confidentiality of the data

transmitted between a web server and a

web client like the browsers

you can monitor file corruption by

comparing hash values before and after

transit

once the hashes match file integrity

checks are valid and data corruption is

avoided

hash functions will always give the same

output for the same input irrespective

of the iteration parameters

it also helps in ensuring that the data

hasn't been tampered with on route to

the receiver of the message hope you

learned something interesting today if

you have any queries regarding the topic

feel free to ask us in the comments

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