docs: 添加管理平台标准加密算法 Kotlin 参考实现

docs/工具箱端-授权对接指南/utils/HashUtil.kt

@@ -0,0 +1,18 @@
+package top.tangyh.lamp.filing.utils
+
+import java.io.InputStream
+import java.security.MessageDigest
+
+object HashUtil {
+    fun calculateFileHash(inputStream: InputStream): String {
+        val digest = MessageDigest.getInstance("SHA-256")
+        val buffer = ByteArray(8192)
+        var bytesRead: Int
+
+        while (inputStream.read(buffer).also { bytesRead = it } != -1) {
+            digest.update(buffer, 0, bytesRead)
+        }
+
+        return digest.digest().joinToString("") { "%02x".format(it) }
+    }
+}