diff --git a/internal/api/handlers_test.go b/internal/api/handlers_test.go
index 247f025..9d82ed5 100644
--- a/internal/api/handlers_test.go
+++ b/internal/api/handlers_test.go
@@ -107,4 +107,3 @@ func TestHandlers(t *testing.T) {
 		}
 	})
 }
-
diff --git a/internal/security/security.go b/internal/security/security.go
index cd2607b..6170759 100644
--- a/internal/security/security.go
+++ b/internal/security/security.go
@@ -3,6 +3,7 @@ package security
 import (
 	"bytes"
 	"context"
+	"crypto/rand"
 	"crypto/sha256"
 	"encoding/hex"
 	"fmt"
@@ -92,13 +93,29 @@ func GetRequestFingerprint(r *http.Request, s *stats.Service) string {
 
 	ua := r.Header.Get("User-Agent")
 	chUA := r.Header.Get("Sec-CH-UA")
+	chPlatform := r.Header.Get("Sec-CH-UA-Platform")
+	chMobile := r.Header.Get("Sec-CH-UA-Mobile")
 
 	hash := sha256.New()
+	hash.Write([]byte("v2|"))
 	hash.Write([]byte(ipStr))
 	hash.Write([]byte("|"))
 	hash.Write([]byte(ua))
 	hash.Write([]byte("|"))
 	hash.Write([]byte(chUA))
+	hash.Write([]byte("|"))
+	hash.Write([]byte(chPlatform))
+	hash.Write([]byte("|"))
+	hash.Write([]byte(chMobile))
+
+	if r.TLS != nil {
+		hash.Write([]byte(fmt.Sprintf("|%d|%d", r.TLS.Version, r.TLS.CipherSuite)))
+	}
+
+	if cookie, err := r.Cookie("_ss_uid"); err == nil {
+		hash.Write([]byte("|"))
+		hash.Write([]byte(cookie.Value))
+	}
 
 	fingerprint := hex.EncodeToString(hash.Sum(nil))
 
@@ -182,6 +199,24 @@ func SecurityMiddleware(s *stats.Service, bb *BotBlocker) func(http.Handler) htt
 			start := time.Now()
 			path := strings.ToLower(r.URL.Path)
 			ua := r.UserAgent()
+
+			if _, err := r.Cookie("_ss_uid"); err != nil {
+				uid := make([]byte, 16)
+				if _, err := rand.Read(uid); err == nil {
+					uidStr := hex.EncodeToString(uid)
+					http.SetCookie(w, &http.Cookie{
+						Name:     "_ss_uid",
+						Value:    uidStr,
+						Path:     "/",
+						Expires:  time.Now().Add(365 * 24 * time.Hour),
+						HttpOnly: true,
+						Secure:   r.TLS != nil || r.Header.Get("X-Forwarded-Proto") == "https",
+						SameSite: http.SameSiteLaxMode,
+					})
+					r.AddCookie(&http.Cookie{Name: "_ss_uid", Value: uidStr})
+				}
+			}
+
 			fingerprint := GetRequestFingerprint(r, s)
 
 			ctx := context.WithValue(r.Context(), FingerprintKey, fingerprint)
diff --git a/internal/security/security_test.go b/internal/security/security_test.go
index 69af34c..640cf4f 100644
--- a/internal/security/security_test.go
+++ b/internal/security/security_test.go
@@ -59,36 +59,41 @@ func TestThrottledReader(t *testing.T) {
 func TestGetRequestFingerprint(t *testing.T) {
 	statsService := stats.NewService("test-hashes.json")
 
-	// IPv4
+	// Same IP, same headers
 	req1 := httptest.NewRequest("GET", "/", nil)
 	req1.RemoteAddr = "1.2.3.4:1234"
+	req1.Header.Set("User-Agent", "Mozilla/5.0")
+	req1.Header.Set("Sec-CH-UA", `"Google Chrome";v="123"`)
 	f1 := GetRequestFingerprint(req1, statsService)
 
 	req2 := httptest.NewRequest("GET", "/", nil)
 	req2.RemoteAddr = "1.2.3.4:5678"
+	req2.Header.Set("User-Agent", "Mozilla/5.0")
+	req2.Header.Set("Sec-CH-UA", `"Google Chrome";v="123"`)
 	f2 := GetRequestFingerprint(req2, statsService)
 	if f1 != f2 {
-		t.Error("fingerprints should match for same IPv4")
+		t.Error("fingerprints should match for same parameters")
 	}
 
-	// X-Forwarded-For
+	// Different UID cookie
 	req3 := httptest.NewRequest("GET", "/", nil)
-	req3.Header.Set("X-Forwarded-For", "5.6.7.8, 1.2.3.4")
+	req3.RemoteAddr = "1.2.3.4:1234"
+	req3.Header.Set("User-Agent", "Mozilla/5.0")
+	req3.Header.Set("Sec-CH-UA", `"Google Chrome";v="123"`)
+	req3.AddCookie(&http.Cookie{Name: "_ss_uid", Value: "uid1"})
 	f3 := GetRequestFingerprint(req3, statsService)
 	if f1 == f3 {
-		t.Error("fingerprints should differ for different IPs")
+		t.Error("fingerprints should differ with different UID cookies")
 	}
 
-	// IPv6 masking
+	// Different Client Hint
 	req4 := httptest.NewRequest("GET", "/", nil)
-	req4.RemoteAddr = "[2001:db8::1]:1234"
+	req4.RemoteAddr = "1.2.3.4:1234"
+	req4.Header.Set("User-Agent", "Mozilla/5.0")
+	req4.Header.Set("Sec-CH-UA", `"Brave";v="123"`)
 	f4 := GetRequestFingerprint(req4, statsService)
-
-	req5 := httptest.NewRequest("GET", "/", nil)
-	req5.RemoteAddr = "[2001:db8::2]:1234"
-	f5 := GetRequestFingerprint(req5, statsService)
-	if f4 != f5 {
-		t.Error("fingerprints should match for same IPv6 /64 prefix")
+	if f1 == f4 {
+		t.Error("fingerprints should differ with different Client Hints")
 	}
 }
 
@@ -116,13 +121,23 @@ func TestSecurityMiddleware(t *testing.T) {
 		t.Errorf("expected 403 for forbidden pattern, got %d", rr.Code)
 	}
 
-	// Test normal request
+	// Test normal request and cookie setting
 	req = httptest.NewRequest("GET", "/api/software", nil)
 	rr = httptest.NewRecorder()
 	handler.ServeHTTP(rr, req)
 	if rr.Code != http.StatusOK {
 		t.Errorf("expected 200 for normal request, got %d", rr.Code)
 	}
+	cookieFound := false
+	for _, c := range rr.Result().Cookies() {
+		if c.Name == "_ss_uid" {
+			cookieFound = true
+			break
+		}
+	}
+	if !cookieFound {
+		t.Error("expected _ss_uid cookie to be set")
+	}
 }
 
 func TestIsPrivateIP_Extended(t *testing.T) {