Cryptography - SHA Algorithm

Quiz

SHA stands for secure hashing algorithm. Data and certificates are hashed using SHA, a modified version of MD5. A hashing algorithm compresses the input data into a smaller, incomprehensible form using bitwise operations, modular additions, and compression functions. You can be asking if hashing can be hacked or decoded. Hashing is one-way, meaning that once data is hashed, a brute force attack is needed to break the resulting hash digest. This is the primary difference between hashing and encryption.

Check out the below image to find out how the SHA algorithm works. Even in the event that a single character changes in the message, SHA is intended to provide a unique hash.

Hashing two similar but distinct messages, like "Heaven" and "heaven is different," is one example. All that differs, however, is one small and one capital letter.

SHAs also help to identify any alterations made to the original message. A user can determine whether a single letter has been altered by comparing the hash digests to the original ones, as they will differ significantly. The deterministic nature of SHA is one of their key features. This means that any computer or user can reproduce the hash digest as long as they know the hash algorithm that was used. One of the reasons that all SSL certificates on the Internet must have been hashed using a SHA-2 method is because of the finite nature of SHAs.

Types of SHA

SHA stands for Secure Hash Algorithm family of cryptographic hash functions. Every SHA type is distinct and comes in a range of numbers. Here are a few common types −

SHA-1 − This was the first version of SHA. It is currently believed to be less secure as a result of these weaknesses.
SHA-2 − This includes several hash algorithms with different digest sizes, such as SHA-224, SHA-256, SHA-384, and SHA-512. They are more secure than SHA-1 and are frequently used.
SHA-3 − The newest member of the SHA family, it was created using different methods than SHA-1 and SHA-2. They include SHA3-224, SHA3-256, SHA3-384, and SHA3-512.

Every kind of SHA generates a unique hash value-a fixed-length character string-from the input data. Among other security-related tasks, these hash values are used in the generation of digital signatures and data integrity verification.

Features of SHA

For cryptography, the Secure Hash Algorithm, or SHA, is useful for several important reasons −

Data Integrity − SHA generates a fixed-size hash result (often 160, 256, 384, or 512 bits) from input data of arbitrary size. Since a small change in the input data would produce a significantly different hash value, it can be used to verify the integrity of data. If the hash values match, this suggests that the input data has not been altered.
Uniqueness − SHA tries to produce unique hash results for a range of inputs. While it is still theoretically possible, modern SHA versions (such SHA-256 and SHA-3) are meant to reduce the probability of two different inputs producing the same hash value (a collision).
Cryptographic Security − Pre-image, second pre-image, collision, and other types of cryptographic attacks are all things that SHA is meant to handle. This means that it will be challenging for an attacker to determine two distinct inputs that result in the same hash value or to reverse-engineer the original input data from its hash value.
Efficiency − SHA algorithms can produce hash values quickly, even for huge amounts of input data, because they are computationally efficient.
Wide Use − SHA is widely used in a number of security applications, like blockchain technology, digital signatures, message authentication codes (MACs), and password hashing.

Implementations

So now we will implement SHA Algorithm using Python, Java and C++ −

Implement using Python

So first we will implement SHA using Python's hashlib library to calculate SHA hashes for a given input string. Here the specific version of SHA can be chosen as per your requirement. The code using Python is as follows −

Example

import hashlib

def calculate_sha(input_data):
   sha_hash = hashlib.sha256()  # Choose different versions sha1(), sha224(), sha384(), etc.
   sha_hash.update(input_data.encode('utf-8'))
   return sha_hash.hexdigest()

input_data = "Hello, Tutorialspoint!"
sha_hash = calculate_sha(input_data)
print("SHA hash:", sha_hash)

Following is the output of the above example −

Input/Output

SHA hash: caba24f8a70cc24277bffcc27aa952723fbf369f315b9657eebf7c7e42b7a1f9

Implement using Java

Now we will implement SHA using Java's MessageDigest library to calculate SHA hashes for a given input string. The code using Java is given below −

Example

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class SHAExample {
   public static void main(String[] args) {
      String input = "Hello, Everyone!";
      try {
         MessageDigest shaDigest = MessageDigest.getInstance("SHA-256"); // Choose different versions like "SHA-1", "SHA-224", "SHA-384", etc.
         byte[] hashBytes = shaDigest.digest(input.getBytes());
         StringBuilder sb = new StringBuilder();
         for (byte b : hashBytes) {
            sb.append(String.format("%02x", b));
         }
         String shaHash = sb.toString();
         System.out.println("SHA hash: " + shaHash);
      } catch (NoSuchAlgorithmException e) {
         e.printStackTrace();
      }
   }
}

Following is the output of the above example −

Input/Output

SHA hash: 06b1f0e2138fdb9f0ae8b37cb7a0c77e9e9af1293aa1bfb4d17e57a36542348c

Future of Hashing

SHA-2 is now the industry standard for hashing algorithms, however SHA-3 may someday overtake it. SHA-3 was released in 2015 by the NIST, which also created SHA-1 and SHA-2. Although, it was never accepted as the industry standard for a number of reasons. When SHA-3 was released, most organisations were already switching from SHA-1 to SHA-2, therefore it made no sense to switch to SHA-3 when SHA-2 was still quite secure.

In addition, this is not exactly correct, SHA-3 was seen as being slower than SHA-2. SHA-3 continues to advance with every year, and while it is slower in software, it is faster in hardware when compared to both SHA-1 and SHA-2.

Avelanche Effect

The hash digest for the original message 'Heaven', hashed with SHA-1, is "06b73bd57b3b938786daed820cb9fa4561bf0e8e." The hash digest for the second 'heaven', similar message hashed using SHA-1 looks like this: "66da9f3b8d9d83f34770a14c38276a69433a535b." We call this phenomenon the avalanche effect. This effect is crucial to cryptography since it means that any modification to the input message might significantly change the result. By doing this, attackers will be prevented from deciphering the original meaning of the hash digest and from informing the message's recipient about any modifications made while it was in transit.

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