Add SHA-1 hash function implementation for generating secure hashes

Author: karthikyandrapu

src/main/java/com/thealgorithms/hashes/SHA1.java

@@ -0,0 +1,73 @@
+package com.thealgorithms.hashes;
+
+import java.math.BigInteger;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Scanner;
+
+/**
+ * The SHA1 class provides a method to generate the SHA-1 hash for a given string.
+ * SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function that produces
+ * a 160-bit (20-byte) hash value. It is commonly used for data integrity verification,
+ * although it is no longer considered secure for cryptographic purposes.
+ * 
+ * @see <a href="https://en.wikipedia.org/wiki/SHA-1">SHA-1 on Wikipedia</a>
+ */
+public class SHA1 {
+
+    /**
+     * Generates the SHA-1 hash of the input string.
+     *
+     * @param input the string to be hashed
+     * @return the SHA-1 hash as a hexadecimal string
+     */
+    public static String getSha1(String input) {
+        try {
+            // Create a MessageDigest instance for SHA-1
+            MessageDigest md = MessageDigest.getInstance("SHA-1");
+            
+            // Compute the SHA-1 digest of the input string
+            byte[] messageDigest = md.digest(input.getBytes());
+            
+            // Convert the byte array into a BigInteger to get the hash in hexadecimal format
+            BigInteger no = new BigInteger(1, messageDigest);
+            
+            // Convert the BigInteger to a hexadecimal string
+            String hashtext = no.toString(16);
+
+            // Pad with leading zeros to ensure the hash is 32 characters long
+            while (hashtext.length() < 32) {
+                hashtext = "0" + hashtext;
+            }
+            
+            // Return the generated SHA-1 hash
+            return hashtext;
+        } catch (NoSuchAlgorithmException e) {
+            // Handle the case where SHA-1 algorithm is not available
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * The main method that takes user input, computes its SHA-1 hash, and prints the result.
+     *
+     * @param args command-line arguments
+     * @throws NoSuchAlgorithmException if the SHA-1 algorithm is not available
+     */
+    public static void main(String args[]) throws NoSuchAlgorithmException {
+        // Create a Scanner object to read input from the user
+        Scanner scanner = new Scanner(System.in);
+        
+        // Prompt the user to enter a string to hash
+        System.out.print("Enter the string to hash: ");
+        
+        // Read the input string from the user
+        String s = scanner.nextLine();
+        
+        // Compute the SHA-1 hash of the input string and print it
+        System.out.println("Your HashCode Generated by SHA-1 is: " + getSha1(s));
+        
+        // Close the Scanner object
+        scanner.close();
+    }
+}

src/test/java/com/thealgorithms/hashes/SHA1.java

@@ -0,0 +1,73 @@
+package com.thealgorithms.hashes;
+
+import java.math.BigInteger;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Scanner;
+
+/**
+ * The SHA1 class provides a method to generate the SHA-1 hash for a given string.
+ * SHA-1 (Secure Hash Algorithm 1) is a cryptographic hash function that produces
+ * a 160-bit (20-byte) hash value. It is commonly used for data integrity verification,
+ * although it is no longer considered secure for cryptographic purposes.
+ * 
+ * @see <a href="https://en.wikipedia.org/wiki/SHA-1">SHA-1 on Wikipedia</a>
+ */
+public class SHA1 {
+
+    /**
+     * Generates the SHA-1 hash of the input string.
+     *
+     * @param input the string to be hashed
+     * @return the SHA-1 hash as a hexadecimal string
+     */
+    public static String getSha1(String input) {
+        try {
+            // Create a MessageDigest instance for SHA-1
+            MessageDigest md = MessageDigest.getInstance("SHA-1");
+            
+            // Compute the SHA-1 digest of the input string
+            byte[] messageDigest = md.digest(input.getBytes());
+            
+            // Convert the byte array into a BigInteger to get the hash in hexadecimal format
+            BigInteger no = new BigInteger(1, messageDigest);
+            
+            // Convert the BigInteger to a hexadecimal string
+            String hashtext = no.toString(16);
+
+            // Pad with leading zeros to ensure the hash is 32 characters long
+            while (hashtext.length() < 32) {
+                hashtext = "0" + hashtext;
+            }
+            
+            // Return the generated SHA-1 hash
+            return hashtext;
+        } catch (NoSuchAlgorithmException e) {
+            // Handle the case where SHA-1 algorithm is not available
+            throw new RuntimeException(e);
+        }
+    }
+
+    /**
+     * The main method that takes user input, computes its SHA-1 hash, and prints the result.
+     *
+     * @param args command-line arguments
+     * @throws NoSuchAlgorithmException if the SHA-1 algorithm is not available
+     */
+    public static void main(String args[]) throws NoSuchAlgorithmException {
+        // Create a Scanner object to read input from the user
+        Scanner scanner = new Scanner(System.in);
+        
+        // Prompt the user to enter a string to hash
+        System.out.print("Enter the string to hash: ");
+        
+        // Read the input string from the user
+        String s = scanner.nextLine();
+        
+        // Compute the SHA-1 hash of the input string and print it
+        System.out.println("Your HashCode Generated by SHA-1 is: " + getSha1(s));
+        
+        // Close the Scanner object
+        scanner.close();
+    }
+}