Package com.privatechain.crypto

Class HashUtil

java.lang.Object

com.privatechain.crypto.HashUtil

public final class HashUtil
extends Object

Utility class providing cryptographic hash functions used throughout the blockchain.

All methods return lowercase hexadecimal strings. BouncyCastle is registered lazily on first use so that the JVM does not pay the registration cost when the class is loaded but no hash is computed (FR-CRYPTO-01 – FR-CRYPTO-03).

Supported algorithms

• sha256(String) / sha256(byte[]) — NIST SHA-256
• sha3_256(String) / sha3_256(byte[]) — Keccak / NIST SHA-3-256
• doubleSha256(String) / doubleSha256(byte[]) — SHA-256(SHA-256(x)), the double-hash used in Bitcoin-style block and transaction IDs

Thread safety

All methods create fresh MessageDigest instances for each call so they are safe to use from multiple threads simultaneously.

 String blockHash = HashUtil.sha256("index|prevHash|merkleRoot|timestamp");
 String txId      = HashUtil.doubleSha256(rawBytes);
 

Since:

1.0.0

See Also:

• ECDSASignatureUtil
• MerkleTree

Method Summary

Modifier and Type	Method	Description
static String	doubleSha256(byte[] data)	Computes SHA-256(SHA-256(data)) on a byte array.
static String	doubleSha256(String input)	Computes SHA-256(SHA-256(input)) on a UTF-8–encoded string.
static String	sha256(byte[] data)	Computes the SHA-256 hash of a byte array.
static String	sha256(String input)	Computes the SHA-256 hash of a UTF-8–encoded string.
static String	sha3_256(byte[] data)	Computes the SHA-3-256 hash of a byte array.
static String	sha3_256(String input)	Computes the SHA-3-256 hash of a UTF-8–encoded string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

sha256

public static String sha256(String input)

Computes the SHA-256 hash of a UTF-8–encoded string.

Parameters:

input - the string to hash (non-null)

Returns:

lowercase 64-character hex string

Throws:

NullPointerException - if input is null

sha256

public static String sha256(byte[] data)

Computes the SHA-256 hash of a byte array.

Parameters:

data - the data to hash (non-null)

Returns:

lowercase 64-character hex string

Throws:

NullPointerException - if data is null

sha3_256

public static String sha3_256(String input)

Computes the SHA-3-256 hash of a UTF-8–encoded string.

SHA-3-256 (Keccak) is used in Ethereum-compatible address derivation and as an alternative to SHA-256 in hash-proof generation.

Parameters:

input - the string to hash (non-null)

Returns:

lowercase 64-character hex string

Throws:

NullPointerException - if input is null

sha3_256

public static String sha3_256(byte[] data)

Computes the SHA-3-256 hash of a byte array.

Parameters:

data - the data to hash (non-null)

Returns:

lowercase 64-character hex string

Throws:

NullPointerException - if data is null

doubleSha256

public static String doubleSha256(String input)

Computes SHA-256(SHA-256(input)) on a UTF-8–encoded string.

Double-hashing is used in Bitcoin-style transaction and block IDs to provide additional collision resistance.

Parameters:

input - the string to hash (non-null)

Returns:

lowercase 64-character hex string

Throws:

NullPointerException - if input is null

doubleSha256

public static String doubleSha256(byte[] data)

Computes SHA-256(SHA-256(data)) on a byte array.

Parameters:

data - the data to hash (non-null)

Returns:

lowercase 64-character hex string

Throws:

NullPointerException - if data is null