SHA1 Hash (original) (raw)

SHA-1 Hash

Last Updated : 1 Jun, 2026

SHA-1 (Secure Hash Algorithm 1) is a cryptographic hashing algorithm that generates a fixed 160-bit hash value from input data, mainly used to verify data integrity. It is now considered insecure due to vulnerabilities and has been replaced by stronger hashing standards.

Produces a 160-bit (40-character hexadecimal) hash output
Formerly used as a Federal Information Processing Standard (FIPS)
Broken by collision attacks, making it unsafe for modern security use

SHA-1 Hashing Algorithm Workflow

The diagram illustrates the SHA-1 hashing process, including message padding, word computation, initialization of hash variables (A, B, C, D, E), execution of 80 rounds in four stages (0–19, 20–39, 40–59, 60–79), and final hash value generation.

SHA_1_Algorithm_Block_Diagram

SHA-1 Hash

Working of SHA-1

The block diagram of the SHA-1 algorithm. Here’s a detailed description of each component and process in the diagram:

Process Flow

**Message (M): The original input data that needs to be hashed.
**Message Padding: The message is padded so its length becomes 448 modulo 512, making it ready for block processing.
**Word Computation: The padded message is divided into 512-bit blocks, each split into 16 words, which are then expanded into 80 words.
**Initialization: Five working variables A, B, C, D, and E are initialized with predefined constant values.
**Round Constants: Four constants (K1 to K4) are used across different round ranges (0–19, 20–39, 40–59, 60–79).
**80 Rounds Processing: The algorithm performs 80 iterations, applying logical operations and transformations on A–E using the expanded words and constants.
**Final Addition: The results of the rounds are added to the initial values of A–E to form the intermediate hash.
**Message Digest (MPX): All values are combined to produce the final 160-bit hash output.

Cryptographic Hash Functions in Java

In Java, cryptographic hash values are generated using the MessageDigest class from the java.security package.

**Supported Algorithms: Java supports multiple hashing algorithms, including MD2, MD5, SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512.

Execution Process

Select algorithm using MessageDigest.getInstance()
Input data is processed into a byte array
Byte array is converted using BigInteger
Final output is displayed as a hexadecimal string

Example Inputs and Outputs

**Input: hello world
**Output: 2aae6c35c94fcfb415dbe95f408b9ce91ee846ed
**Input: GeeksForGeeks
**Output: addf120b430021c36c232c99ef8d926aea2acd6b

Example Implementations

**Example 1: Implementation of SHA-1 in Java

Java `

import java.math.BigInteger; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException;

public class GFG { public static String encryptThisString(String input) { try { // getInstance() method is called with algorithm SHA-1 MessageDigest md = MessageDigest.getInstance("SHA-1");

        // digest() method is called
        // to calculate message digest of the input string
        // returned as array of byte
        byte[] messageDigest = md.digest(input.getBytes());

        // Convert byte array into signum representation
        BigInteger no = new BigInteger(1, messageDigest);

        // Convert message digest into hex value
        String hashtext = no.toString(16);

        // Add preceding 0s to make it 40 digits long
        while (hashtext.length() < 40) {
            hashtext = "0" + hashtext;
        }

        // return the HashText
        return hashtext;
    }

    // For specifying wrong message digest algorithms
    catch (NoSuchAlgorithmException e) {
        throw new RuntimeException(e);
    }
}

// Driver code
public static void main(String args[]) throws NoSuchAlgorithmException {
    System.out.println("HashCode Generated by SHA-1 for:");

    String s1 = "GeeksForGeeks";
    System.out.println("\n" + s1 + " : " + encryptThisString(s1));

    String s2 = "hello world";
    System.out.println("\n" + s2 + " : " + encryptThisString(s2));
}

}

Output

HashCode Generated by SHA-1 for:

GeeksForGeeks : addf120b430021c36c232c99ef8d926aea2acd6b

hello world : 2aae6c35c94fcfb415dbe95f408b9ce91ee846ed

**Explanation: This program uses the MessageDigest class to generate a SHA-1 hash for a given string. The resulting hash is converted into a 40-character hexadecimal value and displayed.

**Example 2: Implementation of SHA-1 in PHP

PHP `

"); $myString = "hello world"; echo $myString." : "; echo sha1($myString); echo ("
"); $myString2 = "GeeksForGeeks"; echo $myString2." : "; echo sha1($myString2); ?>

**Output:

HashCode Generated by SHA-1 for:
hello world : 2aae6c35c94fcfb415dbe95f408b9ce91ee846ed
GeeksForGeeks : addf120b430021c36c232c99ef8d926aea2acd6b

**Explanation: This program uses PHP's built-in sha1() function to generate the SHA-1 hash of a string. The generated hash value is then printed on the webpage.

**Example 3: Implementation of SHA-1 in JavaScript

HTML `

sha1 Hash function