Initial commit: SSH Manager (backend + frontend)

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/main/java/com/sshmanager/service/EncryptionService.java

@@ -0,0 +1,77 @@
+package com.sshmanager.service;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+import javax.crypto.Cipher;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+import java.nio.charset.StandardCharsets;
+import java.security.SecureRandom;
+import java.util.Base64;
+
+@Service
+public class EncryptionService {
+
+    private static final int GCM_IV_LENGTH = 12;
+    private static final int GCM_TAG_LENGTH = 128;
+    private static final String ALGORITHM = "AES/GCM/NoPadding";
+
+    private final byte[] keyBytes;
+
+    public EncryptionService(@Value("${sshmanager.encryption-key}") String base64Key) {
+        this.keyBytes = Base64.getDecoder().decode(base64Key);
+        if (keyBytes.length != 32) {
+            throw new IllegalArgumentException("Encryption key must be 32 bytes (256 bits)");
+        }
+    }
+
+    public String encrypt(String plainText) {
+        if (plainText == null || plainText.isEmpty()) {
+            return null;
+        }
+        try {
+            byte[] iv = new byte[GCM_IV_LENGTH];
+            new SecureRandom().nextBytes(iv);
+
+            SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");
+            GCMParameterSpec gcmSpec = new GCMParameterSpec(GCM_TAG_LENGTH, iv);
+
+            Cipher cipher = Cipher.getInstance(ALGORITHM);
+            cipher.init(Cipher.ENCRYPT_MODE, keySpec, gcmSpec);
+            byte[] encrypted = cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8));
+
+            byte[] combined = new byte[iv.length + encrypted.length];
+            System.arraycopy(iv, 0, combined, 0, iv.length);
+            System.arraycopy(encrypted, 0, combined, iv.length, encrypted.length);
+
+            return Base64.getEncoder().encodeToString(combined);
+        } catch (Exception e) {
+            throw new RuntimeException("Encryption failed", e);
+        }
+    }
+
+    public String decrypt(String encryptedText) {
+        if (encryptedText == null || encryptedText.isEmpty()) {
+            return null;
+        }
+        try {
+            byte[] combined = Base64.getDecoder().decode(encryptedText);
+            byte[] iv = new byte[GCM_IV_LENGTH];
+            byte[] encrypted = new byte[combined.length - GCM_IV_LENGTH];
+            System.arraycopy(combined, 0, iv, 0, iv.length);
+            System.arraycopy(combined, iv.length, encrypted, 0, encrypted.length);
+
+            SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");
+            GCMParameterSpec gcmSpec = new GCMParameterSpec(GCM_TAG_LENGTH, iv);
+
+            Cipher cipher = Cipher.getInstance(ALGORITHM);
+            cipher.init(Cipher.DECRYPT_MODE, keySpec, gcmSpec);
+            byte[] decrypted = cipher.doFinal(encrypted);
+
+            return new String(decrypted, StandardCharsets.UTF_8);
+        } catch (Exception e) {
+            throw new RuntimeException("Decryption failed", e);
+        }
+    }
+}