# Secure Hash Algorithm (SHA) in Python

In this tutorial, we will learn about **Secure Hash Algorithms (SHA) in Python.** First, let’s check out the basics.

**The hash function: **Hash function is used in cryptography to secure a message by encoding it. It takes input of any length and maps it into a fixed size. Every message should have a unique hash value. A small change in the message should extensively change the hash value. Further, it goes without saying that the same message should always result in the same hash value.

**Hash algorithms: **There are many cryptographic algorithms available in python. To access it, python has a predefined library known as *hashlib. *To check the algorithms supported by your current interpreter you can use:

hashlib.algorithms_available

Also, you can use:

hashlib.algorithms_guaranteed

This returns all the algorithms supported on any platform. Implementing this in the code gives us,

import hashlib print(hashlib.algorithms_available) print(hashlib.algorithms_guaranteed)

Output:

{'sha512', 'DSA-SHA', 'SHA224', 'sha', 'ecdsa-with-SHA1', 'DSA', 'sha1', 'sha224', 'md5', 'MD5', 'SHA', 'SHA384', 'SHA1', 'whirlpool', 'SHA256', 'RIPEMD160', 'MD4', 'dsaWithSHA', 'sha256', 'dsaEncryption', 'SHA512', 'sha384', 'ripemd160', 'md4'} {'sha512', 'sha1', 'sha256', 'sha224', 'md5', 'sha384'}

Now that we know about hash functions and algorithms, let us look further into the SHA family.

This tutorial might help you: **How to encode a string in MD5 using Python**

## SHA in Python

Started off in 1993, SHA was revised through a number of versions. SHA-0 was withdrawn a long time ago due to detection of many loopholes. Similarly, SHA-1 is also not recommended and hence is not in use anymore. Next, SHA-2 was introduced. Hash functions in SHA-2 are- SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-512/256. Finally, SHA-3 was written and is currently the latest version of SHA.

Version | Size |
---|---|

SHA-1 | 160 bits |

SHA-256, SHA-384, SHA-224 | 32 bits |

SHA-512 | 64 bits |

The above table shows different SHA versions and their block sizes. Keeping these in mind, let us execute SHA in python. For doing so, we need *haslib* library and *hexdigest()* method.

**Haslib library: **This module provides access to many hash algorithms like md5, SHA-1, etc. Hashlib helps in generating message digest of the original message. (Message digest is a cryptographic hash value of the message resulted using hash algorithms). To use this, simply import it using:

import hashlib

**hexdigest() function: **This method returns the hashed message in hexadecimal format. Syntax:

string.hexdigest()

Also, we need to encode the message to binary before hashing. We can do that by simply using *b’string’ *or using the *encode()* function. If we don’t, we might encounter an error like,

`Unicode-objects must be encoded before hashing`

### How to implement Secure Hash Algorithm (SHA) in Python

Let us now check out the python program to implement different SHA algorithms available.

#import the module import hashlib #encode the message text = hashlib.sha1(b'hello') #convert it to hexadecimal format encrypt = text.hexdigest() #print it print(encrypt)

OUTPUT:

9b71d224bd62f3785d96d46ad3ea3d73319bfbc2890caadae2dff72519673ca72323c3d99ba5c11d7c7acc6e14b8c5da0c4663475c2e5c3adef46f73bcdec043

The above code uses SHA-512. Similarly, we can try out different versions of SHA:

import hashlib text1 = hashlib.sha1(b'hello') encrypt1 = text1.hexdigest() print(encrypt1) text2 = hashlib.sha256(b'hello') encrypt2 = text2.hexdigest() print(encrypt2) text3 = hashlib.sha384(b'hello') encrypt3 = text3.hexdigest() print(encrypt3) text4 = hashlib.sha224(b'hello') encrypt4 = text4.hexdigest() print(encrypt4)

OUTPUT:

aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 59e1748777448c69de6b800d7a33bbfb9ff1b463e44354c3553bcdb9c666fa90125a3c79f90397bdf5f6a13de828684f ea09ae9cc6768c50fcee903ed054556e5bfc8347907f12598aa24193

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