Save signatures to server (#5080)

# Description of Changes  --- ## Checklist ### General - [ ] I have read the [Contribution Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md) - [ ] I have read the [Stirling-PDF Developer Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md) (if applicable) - [ ] I have read the [How to add new languages to Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md) (if applicable) - [ ] I have performed a self-review of my own code - [ ] My changes generate no new warnings ### Documentation - [ ] I have updated relevant docs on [Stirling-PDF's doc repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/) (if functionality has heavily changed) - [ ] I have read the section [Add New Translation Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags) (for new translation tags only) ### Translations (if applicable) - [ ] I ran [`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md) ### UI Changes (if applicable) - [ ] Screenshots or videos demonstrating the UI changes are attached (e.g., as comments or direct attachments in the PR) ### Testing (if applicable) - [ ] I have tested my changes locally. Refer to the [Testing Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing) for more details. --------- Co-authored-by: Anthony Stirling <[email protected]>
2026-07-15 11:00:47 +02:00 · 2025-11-29 19:29:06 +00:00
parent fde449e738
commit 651f17f1c6
19 changed files with 1674 additions and 425 deletions
@@ -26,7 +26,7 @@ import lombok.extern.slf4j.Slf4j;

 import stirling.software.SPDF.model.Dependency;
 import stirling.software.SPDF.model.SignatureFile;
-import stirling.software.SPDF.service.SignatureService;
+import stirling.software.SPDF.service.SharedSignatureService;
 import stirling.software.common.annotations.api.UiDataApi;
 import stirling.software.common.configuration.InstallationPathConfig;
 import stirling.software.common.configuration.RuntimePathConfig;
@@ -40,14 +40,14 @@ import stirling.software.common.util.GeneralUtils;
 public class UIDataController {

    private final ApplicationProperties applicationProperties;
-    private final SignatureService signatureService;
+    private final SharedSignatureService signatureService;
    private final UserServiceInterface userService;
    private final ResourceLoader resourceLoader;
    private final RuntimePathConfig runtimePathConfig;

    public UIDataController(
            ApplicationProperties applicationProperties,
-            SignatureService signatureService,
+            SharedSignatureService signatureService,
            @Autowired(required = false) UserServiceInterface userService,
            ResourceLoader resourceLoader,
            RuntimePathConfig runtimePathConfig) {
@@ -25,7 +25,7 @@ import lombok.Setter;
 import lombok.extern.slf4j.Slf4j;

 import stirling.software.SPDF.model.SignatureFile;
-import stirling.software.SPDF.service.SignatureService;
+import stirling.software.SPDF.service.SharedSignatureService;
 import stirling.software.common.configuration.InstallationPathConfig;
 import stirling.software.common.configuration.RuntimePathConfig;
 import stirling.software.common.service.UserServiceInterface;
@@ -37,13 +37,13 @@ import stirling.software.common.util.GeneralUtils;
@Slf4j
 public class GeneralWebController {

-    private final SignatureService signatureService;
+    private final SharedSignatureService signatureService;
    private final UserServiceInterface userService;
    private final ResourceLoader resourceLoader;
    private final RuntimePathConfig runtimePathConfig;

    public GeneralWebController(
-            SignatureService signatureService,
+            SharedSignatureService signatureService,
            @Autowired(required = false) UserServiceInterface userService,
            ResourceLoader resourceLoader,
            RuntimePathConfig runtimePathConfig) {
@@ -1,48 +0,0 @@
-package stirling.software.SPDF.controller.web;
-
-import java.io.IOException;
-
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.http.HttpStatus;
-import org.springframework.http.MediaType;
-import org.springframework.http.ResponseEntity;
-import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.PathVariable;
-import org.springframework.web.bind.annotation.RequestMapping;
-
-import stirling.software.SPDF.service.SignatureService;
-import stirling.software.common.service.UserServiceInterface;
-
-// @Controller // Disabled - Backend-only mode, no Thymeleaf UI
-@RequestMapping("/api/v1/general")
-public class SignatureController {
-
-    private final SignatureService signatureService;
-
-    private final UserServiceInterface userService;
-
-    public SignatureController(
-            SignatureService signatureService,
-            @Autowired(required = false) UserServiceInterface userService) {
-        this.signatureService = signatureService;
-        this.userService = userService;
-    }
-
-    @GetMapping("/sign/{fileName}")
-    public ResponseEntity<byte[]> getSignature(@PathVariable(name = "fileName") String fileName)
-            throws IOException {
-        String username = "NON_SECURITY_USER";
-        if (userService != null) {
-            username = userService.getCurrentUsername();
-        }
-        // Verify access permission
-        if (!signatureService.hasAccessToFile(username, fileName)) {
-            return ResponseEntity.status(HttpStatus.FORBIDDEN).build();
-        }
-        byte[] imageBytes = signatureService.getSignatureBytes(username, fileName);
-        return ResponseEntity.ok()
-                .contentType( // Adjust based on file type
-                        MediaType.IMAGE_JPEG)
-                .body(imageBytes);
-    }
-}
@@ -0,0 +1,84 @@
+package stirling.software.SPDF.controller.web;
+
+import java.io.IOException;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import lombok.extern.slf4j.Slf4j;
+
+import stirling.software.SPDF.service.SharedSignatureService;
+import stirling.software.common.service.PersonalSignatureServiceInterface;
+import stirling.software.common.service.UserServiceInterface;
+
+/**
+ * Unified signature image controller that works for both authenticated and unauthenticated users.
+ * Uses composition pattern: - Core SharedSignatureService (always available): reads shared signatures -
+ * PersonalSignatureService (proprietary, optional): reads personal signatures For authenticated
+ * signature management (save/delete), see proprietary SignatureController.
+ */
+@Slf4j
+@RestController
+@RequestMapping("/api/v1/general")
+public class SignatureImageController {
+
+    private final SharedSignatureService sharedSignatureService;
+    private final PersonalSignatureServiceInterface personalSignatureService;
+    private final UserServiceInterface userService;
+
+    public SignatureImageController(
+            SharedSignatureService sharedSignatureService,
+            @Autowired(required = false) PersonalSignatureServiceInterface personalSignatureService,
+            @Autowired(required = false) UserServiceInterface userService) {
+        this.sharedSignatureService = sharedSignatureService;
+        this.personalSignatureService = personalSignatureService;
+        this.userService = userService;
+    }
+
+    /**
+     * Get a signature image (works for both authenticated and unauthenticated users). -
+     * Authenticated with proprietary: tries personal first, then shared - Unauthenticated or
+     * community: tries shared only
+     */
+    @GetMapping("/signatures/{fileName}")
+    public ResponseEntity<byte[]> getSignature(@PathVariable(name = "fileName") String fileName) {
+        try {
+            byte[] imageBytes = null;
+
+            // If proprietary service available and user authenticated, try personal folder first
+            if (personalSignatureService != null && userService != null) {
+                try {
+                    String username = userService.getCurrentUsername();
+                    imageBytes =
+                            personalSignatureService.getPersonalSignatureBytes(username, fileName);
+                } catch (Exception e) {
+                    // Not found in personal folder or not authenticated, will try shared
+                    log.debug("Personal signature not found, trying shared: {}", e.getMessage());
+                }
+            }
+
+            // If not found in personal (or no personal service), try shared
+            if (imageBytes == null) {
+                imageBytes = sharedSignatureService.getSharedSignatureBytes(fileName);
+            }
+
+            // Determine content type from file extension
+            MediaType contentType = MediaType.IMAGE_PNG; // Default
+            String lowerFileName = fileName.toLowerCase();
+            if (lowerFileName.endsWith(".jpg") || lowerFileName.endsWith(".jpeg")) {
+                contentType = MediaType.IMAGE_JPEG;
+            }
+
+            return ResponseEntity.ok().contentType(contentType).body(imageBytes);
+        } catch (IOException e) {
+            log.debug("Signature not found: {}", fileName);
+            return ResponseEntity.status(HttpStatus.NOT_FOUND).build();
+        }
+    }
+}
@@ -0,0 +1,18 @@
+package stirling.software.SPDF.model.api.signature;
+
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+public class SavedSignatureRequest {
+    private String id;
+    private String label;
+    private String type; // "canvas", "image", "text"
+    private String scope; // "personal", "shared"
+    private String dataUrl; // For canvas and image types
+    private String signerName; // For text type
+    private String fontFamily; // For text type
+    private Integer fontSize; // For text type
+    private String textColor; // For text type
+}
@@ -0,0 +1,22 @@
+package stirling.software.SPDF.model.api.signature;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@NoArgsConstructor
+@AllArgsConstructor
+public class SavedSignatureResponse {
+    private String id;
+    private String label;
+    private String type; // "canvas", "image", "text"
+    private String scope; // "personal", "shared"
+    private String dataUrl; // For canvas and image types (or URL to fetch image)
+    private String signerName; // For text type
+    private String fontFamily; // For text type
+    private Integer fontSize; // For text type
+    private String textColor; // For text type
+    private Long createdAt;
+    private Long updatedAt;
+}
@@ -0,0 +1,308 @@
+package stirling.software.SPDF.service;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
+import java.util.Base64;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.springframework.stereotype.Service;
+import org.springframework.util.StringUtils;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import lombok.extern.slf4j.Slf4j;
+
+import stirling.software.SPDF.model.SignatureFile;
+import stirling.software.SPDF.model.api.signature.SavedSignatureRequest;
+import stirling.software.SPDF.model.api.signature.SavedSignatureResponse;
+import stirling.software.common.configuration.InstallationPathConfig;
+
+@Service
+@Slf4j
+public class SharedSignatureService {
+
+    private final String SIGNATURE_BASE_PATH;
+    private final String ALL_USERS_FOLDER = "ALL_USERS";
+    private final ObjectMapper objectMapper;
+
+    public SharedSignatureService() {
+        SIGNATURE_BASE_PATH = InstallationPathConfig.getSignaturesPath();
+        this.objectMapper = new ObjectMapper();
+    }
+
+    public boolean hasAccessToFile(String username, String fileName) throws IOException {
+        validateFileName(fileName);
+        // Check if file exists in user's personal folder or ALL_USERS folder
+        Path userPath = Paths.get(SIGNATURE_BASE_PATH, username, fileName);
+        Path allUsersPath = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER, fileName);
+
+        return Files.exists(userPath) || Files.exists(allUsersPath);
+    }
+
+    public List<SignatureFile> getAvailableSignatures(String username) {
+        List<SignatureFile> signatures = new ArrayList<>();
+
+        // Get signatures from user's personal folder
+        if (StringUtils.hasText(username)) {
+            Path userFolder = Paths.get(SIGNATURE_BASE_PATH, username);
+            if (Files.exists(userFolder)) {
+                try {
+                    signatures.addAll(getSignaturesFromFolder(userFolder, "Personal"));
+                } catch (IOException e) {
+                    log.error("Error reading user signatures folder", e);
+                }
+            }
+        }
+
+        // Get signatures from ALL_USERS folder
+        Path allUsersFolder = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER);
+        if (Files.exists(allUsersFolder)) {
+            try {
+                signatures.addAll(getSignaturesFromFolder(allUsersFolder, "Shared"));
+            } catch (IOException e) {
+                log.error("Error reading shared signatures folder", e);
+            }
+        }
+
+        return signatures;
+    }
+
+    private List<SignatureFile> getSignaturesFromFolder(Path folder, String category)
+            throws IOException {
+        try (Stream<Path> stream = Files.list(folder)) {
+            return stream.filter(this::isImageFile)
+                    .map(path -> new SignatureFile(path.getFileName().toString(), category))
+                    .toList();
+        }
+    }
+
+    /**
+     * Get a signature from the shared (ALL_USERS) folder. This is always available for both
+     * authenticated and unauthenticated users.
+     */
+    public byte[] getSharedSignatureBytes(String fileName) throws IOException {
+        validateFileName(fileName);
+        Path allUsersPath = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER, fileName);
+        if (!Files.exists(allUsersPath)) {
+            throw new FileNotFoundException("Shared signature file not found");
+        }
+        return Files.readAllBytes(allUsersPath);
+    }
+
+    private boolean isImageFile(Path path) {
+        String fileName = path.getFileName().toString().toLowerCase();
+        return fileName.endsWith(".jpg") || fileName.endsWith(".jpeg") || fileName.endsWith(".png");
+    }
+
+    private void validateFileName(String fileName) {
+        if (fileName.contains("..") || fileName.contains("/") || fileName.contains("\\")) {
+            throw new IllegalArgumentException("Invalid filename");
+        }
+        // Only allow alphanumeric, hyphen, underscore, and dot (for extensions)
+        if (!fileName.matches("^[a-zA-Z0-9_.-]+$")) {
+            throw new IllegalArgumentException("Filename contains invalid characters");
+        }
+    }
+
+    private String validateAndNormalizeExtension(String extension) {
+        String normalized = extension.toLowerCase().trim();
+        // Whitelist only safe image extensions
+        if (normalized.equals("png") || normalized.equals("jpg") || normalized.equals("jpeg")) {
+            return normalized;
+        }
+        throw new IllegalArgumentException("Unsupported image extension: " + extension);
+    }
+
+    private void verifyPathWithinDirectory(Path resolvedPath, Path targetDirectory)
+            throws IOException {
+        Path canonicalTarget = targetDirectory.toAbsolutePath().normalize();
+        Path canonicalResolved = resolvedPath.toAbsolutePath().normalize();
+        if (!canonicalResolved.startsWith(canonicalTarget)) {
+            throw new IOException("Resolved path is outside the target directory");
+        }
+    }
+
+    /** Save a signature as image file */
+    public SavedSignatureResponse saveSignature(String username, SavedSignatureRequest request)
+            throws IOException {
+        validateFileName(request.getId());
+
+        // Determine folder based on scope
+        String scope = request.getScope();
+        if (scope == null || scope.isEmpty()) {
+            scope = "personal"; // Default to personal
+        }
+
+        String folderName = "shared".equals(scope) ? ALL_USERS_FOLDER : username;
+        Path targetFolder = Paths.get(SIGNATURE_BASE_PATH, folderName);
+        Files.createDirectories(targetFolder);
+
+        long timestamp = System.currentTimeMillis();
+
+        SavedSignatureResponse response = new SavedSignatureResponse();
+        response.setId(request.getId());
+        response.setLabel(request.getLabel());
+        response.setType(request.getType());
+        response.setScope(scope);
+        response.setCreatedAt(timestamp);
+        response.setUpdatedAt(timestamp);
+
+        // Extract and save image data
+        String dataUrl = request.getDataUrl();
+        if (dataUrl != null && dataUrl.startsWith("data:image/")) {
+            // Extract base64 data
+            String base64Data = dataUrl.substring(dataUrl.indexOf(",") + 1);
+            byte[] imageBytes = Base64.getDecoder().decode(base64Data);
+
+            // Determine and validate file extension from data URL
+            String mimeType = dataUrl.substring(dataUrl.indexOf(":") + 1, dataUrl.indexOf(";"));
+            String rawExtension = mimeType.substring(mimeType.indexOf("/") + 1);
+            String extension = validateAndNormalizeExtension(rawExtension);
+
+            // Save image file only
+            String imageFileName = request.getId() + "." + extension;
+            Path imagePath = targetFolder.resolve(imageFileName);
+
+            // Verify path is within target directory
+            verifyPathWithinDirectory(imagePath, targetFolder);
+
+            Files.write(
+                    imagePath,
+                    imageBytes,
+                    StandardOpenOption.CREATE,
+                    StandardOpenOption.TRUNCATE_EXISTING);
+
+            // Store reference to image file
+            response.setDataUrl("/api/v1/general/sign/" + imageFileName);
+        }
+
+        log.info("Saved signature {} for user {}", request.getId(), username);
+        return response;
+    }
+
+    /** Get all saved signatures for a user */
+    public List<SavedSignatureResponse> getSavedSignatures(String username) throws IOException {
+        List<SavedSignatureResponse> signatures = new ArrayList<>();
+
+        // Load personal signatures
+        Path personalFolder = Paths.get(SIGNATURE_BASE_PATH, username);
+        if (Files.exists(personalFolder)) {
+            try (Stream<Path> stream = Files.list(personalFolder)) {
+                stream.filter(this::isImageFile)
+                        .forEach(
+                                path -> {
+                                    try {
+                                        String fileName = path.getFileName().toString();
+                                        String id =
+                                                fileName.substring(0, fileName.lastIndexOf('.'));
+
+                                        SavedSignatureResponse sig = new SavedSignatureResponse();
+                                        sig.setId(id);
+                                        sig.setLabel(id); // Use ID as label
+                                        sig.setType("image"); // Default type
+                                        sig.setScope("personal");
+                                        sig.setDataUrl("/api/v1/general/sign/" + fileName);
+                                        sig.setCreatedAt(
+                                                Files.getLastModifiedTime(path).toMillis());
+                                        sig.setUpdatedAt(
+                                                Files.getLastModifiedTime(path).toMillis());
+
+                                        signatures.add(sig);
+                                    } catch (IOException e) {
+                                        log.error("Error reading signature file: " + path, e);
+                                    }
+                                });
+            }
+        }
+
+        // Load shared signatures
+        Path sharedFolder = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER);
+        if (Files.exists(sharedFolder)) {
+            try (Stream<Path> stream = Files.list(sharedFolder)) {
+                stream.filter(this::isImageFile)
+                        .forEach(
+                                path -> {
+                                    try {
+                                        String fileName = path.getFileName().toString();
+                                        String id =
+                                                fileName.substring(0, fileName.lastIndexOf('.'));
+
+                                        SavedSignatureResponse sig = new SavedSignatureResponse();
+                                        sig.setId(id);
+                                        sig.setLabel(id); // Use ID as label
+                                        sig.setType("image"); // Default type
+                                        sig.setScope("shared");
+                                        sig.setDataUrl("/api/v1/general/sign/" + fileName);
+                                        sig.setCreatedAt(
+                                                Files.getLastModifiedTime(path).toMillis());
+                                        sig.setUpdatedAt(
+                                                Files.getLastModifiedTime(path).toMillis());
+
+                                        signatures.add(sig);
+                                    } catch (IOException e) {
+                                        log.error("Error reading signature file: " + path, e);
+                                    }
+                                });
+            }
+        }
+
+        return signatures;
+    }
+
+    /** Delete a saved signature */
+    public void deleteSignature(String username, String signatureId) throws IOException {
+        validateFileName(signatureId);
+
+        // Try to find and delete image file in personal folder
+        Path personalFolder = Paths.get(SIGNATURE_BASE_PATH, username);
+        boolean deleted = false;
+
+        if (Files.exists(personalFolder)) {
+            try (Stream<Path> stream = Files.list(personalFolder)) {
+                List<Path> matchingFiles =
+                        stream.filter(
+                                        path ->
+                                                path.getFileName()
+                                                        .toString()
+                                                        .startsWith(signatureId + "."))
+                                .toList();
+                for (Path file : matchingFiles) {
+                    Files.delete(file);
+                    deleted = true;
+                }
+            }
+        }
+
+        // Try shared folder if not found in personal
+        if (!deleted) {
+            Path sharedFolder = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER);
+            if (Files.exists(sharedFolder)) {
+                try (Stream<Path> stream = Files.list(sharedFolder)) {
+                    List<Path> matchingFiles =
+                            stream.filter(
+                                            path ->
+                                                    path.getFileName()
+                                                            .toString()
+                                                            .startsWith(signatureId + "."))
+                                    .toList();
+                    for (Path file : matchingFiles) {
+                        Files.delete(file);
+                        deleted = true;
+                    }
+                }
+            }
+        }
+
+        if (!deleted) {
+            throw new FileNotFoundException("Signature not found");
+        }
+
+        log.info("Deleted signature {} for user {}", signatureId, username);
+    }
+}
@@ -1,107 +0,0 @@
-package stirling.software.SPDF.service;
-
-import java.io.FileNotFoundException;
-import java.io.IOException;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.stream.Stream;
-
-import org.springframework.stereotype.Service;
-import org.springframework.util.StringUtils;
-
-import lombok.extern.slf4j.Slf4j;
-
-import stirling.software.SPDF.model.SignatureFile;
-import stirling.software.common.configuration.InstallationPathConfig;
-
-@Service
-@Slf4j
-public class SignatureService {
-
-    private final String SIGNATURE_BASE_PATH;
-    private final String ALL_USERS_FOLDER = "ALL_USERS";
-
-    public SignatureService() {
-        SIGNATURE_BASE_PATH = InstallationPathConfig.getSignaturesPath();
-    }
-
-    public boolean hasAccessToFile(String username, String fileName) throws IOException {
-        validateFileName(fileName);
-        // Check if file exists in user's personal folder or ALL_USERS folder
-        Path userPath = Paths.get(SIGNATURE_BASE_PATH, username, fileName);
-        Path allUsersPath = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER, fileName);
-
-        return Files.exists(userPath) || Files.exists(allUsersPath);
-    }
-
-    public List<SignatureFile> getAvailableSignatures(String username) {
-        List<SignatureFile> signatures = new ArrayList<>();
-
-        // Get signatures from user's personal folder
-        if (StringUtils.hasText(username)) {
-            Path userFolder = Paths.get(SIGNATURE_BASE_PATH, username);
-            if (Files.exists(userFolder)) {
-                try {
-                    signatures.addAll(getSignaturesFromFolder(userFolder, "Personal"));
-                } catch (IOException e) {
-                    log.error("Error reading user signatures folder", e);
-                }
-            }
-        }
-
-        // Get signatures from ALL_USERS folder
-        Path allUsersFolder = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER);
-        if (Files.exists(allUsersFolder)) {
-            try {
-                signatures.addAll(getSignaturesFromFolder(allUsersFolder, "Shared"));
-            } catch (IOException e) {
-                log.error("Error reading shared signatures folder", e);
-            }
-        }
-
-        return signatures;
-    }
-
-    private List<SignatureFile> getSignaturesFromFolder(Path folder, String category)
-            throws IOException {
-        try (Stream<Path> stream = Files.list(folder)) {
-            return stream.filter(this::isImageFile)
-                    .map(path -> new SignatureFile(path.getFileName().toString(), category))
-                    .toList();
-        }
-    }
-
-    public byte[] getSignatureBytes(String username, String fileName) throws IOException {
-        validateFileName(fileName);
-        // First try user's personal folder
-        Path userPath = Paths.get(SIGNATURE_BASE_PATH, username, fileName);
-        if (Files.exists(userPath)) {
-            return Files.readAllBytes(userPath);
-        }
-
-        // Then try ALL_USERS folder
-        Path allUsersPath = Paths.get(SIGNATURE_BASE_PATH, ALL_USERS_FOLDER, fileName);
-        if (Files.exists(allUsersPath)) {
-            return Files.readAllBytes(allUsersPath);
-        }
-
-        throw new FileNotFoundException("Signature file not found");
-    }
-
-    private boolean isImageFile(Path path) {
-        String fileName = path.getFileName().toString().toLowerCase();
-        return fileName.endsWith(".jpg")
-                || fileName.endsWith(".jpeg")
-                || fileName.endsWith(".png")
-                || fileName.endsWith(".gif");
-    }
-
-    private void validateFileName(String fileName) {
-        if (fileName.contains("..") || fileName.contains("/") || fileName.contains("\\")) {
-            throw new IllegalArgumentException("Invalid filename");
-        }
-    }
-}