diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6c22a4a..01f6ae4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Change Log
 
+## 1.0.2 (2024-05-)
+
+- feat: add `sid` method
+
 ## 1.0.1 (2024-04-03)
 
 - `machineId`: Fix bug on Windows
diff --git a/README.md b/README.md
index 159b934..f831367 100644
--- a/README.md
+++ b/README.md
@@ -63,6 +63,20 @@ This method returns the same value for every user on the system.
 console.log(await machineId()); // a642d9e1-6063-4da7-8ea8-2298f989d01d
 ```
 
+### `sid (Promise<string>)`
+
+Gets the Secutify Identifier (SID) value for the current user on the device. Throws an error if the value is not obtained.
+
+The SID value is only supported on Windows and macOS. Other OSes throw an error.
+
+Also, the SID value used on macOS is a value created for the directory service. If you don't trust this value, use the `machineId` method instead.
+
+This value can be changed by the user.
+
+```javascript
+console.log(await sid()); // S-1-5-21-406418252-5582013529-1321253100-2001
+```
+
 ## Contribute
 
 You can report issues on [GitHub Issue Tracker](https://github.com/jooy2/machini/issues). You can also request a pull to fix bugs and add frequently used features.
diff --git a/lib/index.ts b/lib/index.ts
index 01efde3..56948e4 100644
--- a/lib/index.ts
+++ b/lib/index.ts
@@ -1,6 +1,8 @@
-import { platform } from 'os';
+import { platform, homedir, userInfo } from 'os';
 import { exec as processExec } from 'child_process';
 
+declare type AnyValueObject = { [key: string]: any };
+
 const execCommand = (platformName: string, command: string): Promise<string> =>
 	new Promise((resolve, reject) => {
 		const execCommandProcess = processExec(
@@ -53,8 +55,76 @@ export default class Machini {
 
 		throw new Error('Failed to get machine id');
 	}
+
+	static async sid(): Promise<string> {
+		const platformName = platform();
+
+		if (platformName === 'win32') {
+			try {
+				const profileLists = await execCommand(
+					platformName,
+					`REG QUERY "HKLM\\SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\ProfileList" /s`
+				);
+
+				const profiles: AnyValueObject = {};
+				const sections = profileLists.split('HKEY_LOCAL_MACHINE\\');
+
+				sections.forEach((section) => {
+					const lines = section
+						.split('\n')
+						.map((line) => line.trim())
+						.filter((line) => line);
+
+					if (lines.length > 0) {
+						const keyName: string = lines[0].split('\\').pop() || 'Unknown';
+						const profileImagePath = lines.find((line) => line.startsWith('ProfileImagePath'));
+
+						if (profileImagePath) {
+							profiles[keyName] = profileImagePath.split('    ').pop() || 'Unknown';
+						}
+					}
+				});
+
+				for (let i = 0; i < Object.keys(profiles).length; i += 1) {
+					const key = Object.keys(profiles)[i];
+					const value = profiles[key];
+
+					if (value === homedir()) {
+						return key;
+					}
+				}
+			} catch (error) {
+				if (error instanceof Error) {
+					throw new Error(error?.message);
+				}
+			}
+
+			throw new Error('Failed to get machine id');
+		}
+
+		if (platformName === 'darwin') {
+			try {
+				const execResult = await execCommand(
+					platformName,
+					`dsmemberutil getsid -U ${userInfo().username}`
+				);
+
+				if (execResult) {
+					return execResult.replace(/\r?\n/g, '');
+				}
+			} catch (error) {
+				if (error instanceof Error) {
+					throw new Error(error?.message);
+				}
+			}
+
+			throw new Error('Failed to get machine id');
+		}
+
+		throw new Error('Not supported on this operating system.');
+	}
 }
 
 export { Machini };
 
-export const { machineId } = Machini;
+export const { machineId, sid } = Machini;
diff --git a/test/index.spec.ts b/test/index.spec.ts
index 203ce13..2e0eaf8 100644
--- a/test/index.spec.ts
+++ b/test/index.spec.ts
@@ -1,13 +1,13 @@
 import assert from 'assert';
-import { machineId } from '../dist';
-
-/*
- * Sample Response:
- * Windows: a642d9e1-6063-4da7-8ea8-2298f989d01d
- * Linux: 5c6ee51d3e514eb4883e4373e320192c
- * macOS: BAC04154-124A-56E1-BFEB-D6D94FE5DBC0
- */
+import { machineId, sid } from '../dist';
+
 describe('Module Test', () => {
+	/*
+	 * Sample Response:
+	 * Windows: a642d9e1-6063-4da7-8ea8-2298f989d01d
+	 * Linux: 5c6ee51d3e514eb4883e4373e320192c
+	 * macOS: BAC04154-124A-56E1-BFEB-D6D94FE5DBC0
+	 */
 	it('machineId', async () => {
 		const mId = await machineId();
 
@@ -26,4 +26,17 @@ describe('Module Test', () => {
 
 		assert.match(mId, regex);
 	});
+
+	// Example: S-1-5-21-406418252-5582013529-1321253100-2001
+	it('sid', async () => {
+		const { platform } = process;
+
+		if (platform !== 'win32' && platform !== 'darwin') {
+			return;
+		}
+
+		const sidResult = await sid();
+
+		assert.match(sidResult, /^S-1-[0-59]-\d{2}-\d{8,10}-\d{8,10}-\d{8,10}-[1-9]\d{3}/);
+	});
 });