feat: added hash utils

server/src/main/kotlin/org/ccoin/utils/HashUtils.kt

@@ -0,0 +1,80 @@
+package org.ccoin.utils
+
+import java.security.MessageDigest
+import java.security.SecureRandom
+
+object HashUtils {
+    private val secureRandom = SecureRandom()
+    
+    /** Computes SHA-256 hash of a byte array */
+    fun sha256(data: ByteArray): ByteArray = MessageDigest.getInstance("SHA-256").digest(data)
+    
+    /** Computes SHA-256 hash of a string and returns hex string */
+    fun sha256Hex(input: String): String = sha256(input.toByteArray()).toHexString()
+    
+    /** Computes double SHA-256 hash (like Bitcoin) */
+    fun doubleSha256(data: ByteArray): ByteArray = sha256(sha256(data))
+    
+    /** Computes double SHA-256 hash and returns hex string */
+    fun doubleSha256Hex(input: String): String = doubleSha256(input.toByteArray()).toHexString()
+    
+    /** Converts byte array to hex string */
+    fun ByteArray.toHexString(): String = joinToString("") { "%02x".format(it) }
+    
+    /** Converts hex string to byte array */
+    fun String.hexToByteArray(): ByteArray {
+        require(length % 2 == 0) { "Hex string must have even length" }
+        return chunked(2).map { it.toInt(16).toByte() }.toByteArray()
+    }
+    
+    /** Validates if string is valid hex */
+    fun isValidHex(hex: String): Boolean = hex.all { it.isDigit() || it.lowercaseChar() in 'a'..'f' }
+    
+    /** Generates a random hash for testing purposes */
+    fun generateRandomHash(): String {
+        val randomBytes = ByteArray(32)
+        secureRandom.nextBytes(randomBytes)
+        return randomBytes.toHexString()
+    }
+    
+    /** Computes hash with salt for additional security */
+    fun hashWithSalt(input: String, salt: String): String = sha256Hex("$input:$salt")
+    
+    /** Generates a random salt */
+    fun generateSalt(length: Int = 16): String {
+        val saltBytes = ByteArray(length)
+        secureRandom.nextBytes(saltBytes)
+        return saltBytes.toHexString()
+    }
+    
+    /** Computes HMAC-SHA256 */
+    fun hmacSha256(key: String, message: String): String {
+        val keyBytes = key.toByteArray()
+        val messageBytes = message.toByteArray()
+        
+        val blockSize = 64
+        val adjustedKey = when {
+            keyBytes.size > blockSize -> sha256(keyBytes)
+            keyBytes.size < blockSize -> keyBytes + ByteArray(blockSize - keyBytes.size)
+            else -> keyBytes
+        }
+        
+        val outerPad = ByteArray(blockSize) { (adjustedKey[it].toInt() xor 0x5c).toByte() }
+        val innerPad = ByteArray(blockSize) { (adjustedKey[it].toInt() xor 0x36).toByte() }
+        
+        val innerHash = sha256(innerPad + messageBytes)
+        val finalHash = sha256(outerPad + innerHash)
+        
+        return finalHash.toHexString()
+    }
+    
+    /** Validates hash format (64 character hex string for SHA-256) */
+    fun isValidSha256Hash(hash: String): Boolean = hash.length == 64 && isValidHex(hash)
+    
+    /** Computes checksum for data integrity */
+    fun computeChecksum(data: String): String = sha256Hex(data).take(8)
+    
+    /** Validates data against checksum */
+    fun validateChecksum(data: String, checksum: String): Boolean = computeChecksum(data) == checksum
+}
+