Sha256 Hashes in Groovy

In Groovy, we can compute SHA256 hashes using the built-in java.security.MessageDigest class. SHA256 hashes are frequently used to compute short identities for binary or text blobs. For example, TLS/SSL certificates use SHA256 to compute a certificate’s signature. Here’s how to compute SHA256 hashes in Groovy:

import java.security.MessageDigest

String s = "sha256 this string"

// Create a MessageDigest instance for SHA-256
def digest = MessageDigest.getInstance("SHA-256")

// Update the digest with the byte representation of the string
digest.update(s.getBytes("UTF-8"))

// Get the hash's bytes
byte[] hashBytes = digest.digest()

// Convert the byte array to hexadecimal format
def hexString = hashBytes.encodeHex().toString()

println s
println hexString

Running the program computes the hash and prints it in a human-readable hex format.

$ groovy sha256_hashes.groovy
sha256 this string
1af1dfa857bf1d8814fe1af8983c18080019922e557f15a8a0678ff2b9c8a95c

You can compute other hashes using a similar pattern to the one shown above. For example, to compute SHA512 hashes, you would use MessageDigest.getInstance("SHA-512").

Note that if you need cryptographically secure hashes, you should carefully research hash strength!

In this Groovy example:

1. We import the java.security.MessageDigest class, which provides the functionality for computing hashes.

2. We create a MessageDigest instance for SHA-256 using MessageDigest.getInstance("SHA-256").

3. We update the digest with the byte representation of our string using digest.update(s.getBytes("UTF-8")).

4. We finalize the hash computation and get the result as a byte array using digest.digest().

5. We convert the byte array to a hexadecimal string for readable output.

This approach provides the same functionality as the original example, but uses Groovy’s syntax and the Java security libraries that Groovy can access.