diff --git a/src/lib/security/logger.test.ts b/src/lib/security/logger.test.ts
new file mode 100644
index 0000000..19d9a6b
--- /dev/null
+++ b/src/lib/security/logger.test.ts
@@ -0,0 +1,49 @@
+import { SecurityLogger, SecurityEventType } from './logger';
+
+describe('Security Logging System', () => {
+  let logger: SecurityLogger;
+
+  beforeEach(() => {
+    logger = new SecurityLogger();
+  });
+
+  test('should log security events', () => {
+    logger.logEvent({
+      type: SecurityEventType.CAPTCHA_FAILED,
+      ip: '192.168.1.1',
+      email: 'test@example.com',
+      details: { reason: 'Invalid answer' },
+    });
+
+    const logs = logger.getRecentLogs(10);
+    expect(logs.length).toBe(1);
+    expect(logs[0].type).toBe(SecurityEventType.CAPTCHA_FAILED);
+  });
+
+  test('should detect suspicious activity', () => {
+    for (let i = 0; i < 6; i++) {
+      logger.logEvent({
+        type: SecurityEventType.CAPTCHA_FAILED,
+        ip: '192.168.1.2',
+        email: 'suspicious@example.com',
+        details: {},
+      });
+    }
+
+    const suspiciousIPs = logger.getSuspiciousIPs();
+    expect(suspiciousIPs).toContain('192.168.1.2');
+  });
+
+  test('should clear old logs', () => {
+    logger.logEvent({
+      type: SecurityEventType.RATE_LIMIT_EXCEEDED,
+      ip: '192.168.1.3',
+      details: {},
+    });
+
+    logger.clearOldLogs(0);
+
+    const logs = logger.getRecentLogs(10);
+    expect(logs.length).toBe(0);
+  });
+});
diff --git a/src/lib/security/logger.ts b/src/lib/security/logger.ts
new file mode 100644
index 0000000..f53c908
--- /dev/null
+++ b/src/lib/security/logger.ts
@@ -0,0 +1,107 @@
+export enum SecurityEventType {
+  CAPTCHA_FAILED = 'captcha_failed',
+  CAPTCHA_EXPIRED = 'captcha_expired',
+  RATE_LIMIT_EXCEEDED = 'rate_limit_exceeded',
+  MALICIOUS_CONTENT = 'malicious_content',
+  XSS_ATTEMPT = 'xss_attempt',
+  SQL_INJECTION_ATTEMPT = 'sql_injection_attempt',
+  SUSPICIOUS_IP = 'suspicious_ip',
+  BLOCKED_REQUEST = 'blocked_request',
+}
+
+export interface SecurityEvent {
+  type: SecurityEventType;
+  timestamp: number;
+  ip?: string;
+  email?: string;
+  userAgent?: string;
+  details?: Record<string, any>;
+}
+
+export interface SuspiciousActivity {
+  ip: string;
+  eventCount: number;
+  lastSeen: number;
+  eventTypes: SecurityEventType[];
+}
+
+class InMemorySecurityLogger {
+  private events: SecurityEvent[] = [];
+  private ipActivity = new Map<string, number>();
+
+  logEvent(event: Omit<SecurityEvent, 'timestamp'>): void {
+    const fullEvent: SecurityEvent = {
+      ...event,
+      timestamp: Date.now(),
+    };
+
+    this.events.push(fullEvent);
+
+    if (event.ip) {
+      const currentCount = this.ipActivity.get(event.ip) || 0;
+      this.ipActivity.set(event.ip, currentCount + 1);
+    }
+
+    console.log(`[Security] ${event.type}:`, event);
+  }
+
+  getRecentLogs(limit: number = 100): SecurityEvent[] {
+    return this.events.slice(-limit);
+  }
+
+  getSuspiciousIPs(threshold: number = 5): string[] {
+    const suspicious: string[] = [];
+    for (const [ip, count] of this.ipActivity.entries()) {
+      if (count >= threshold) {
+        suspicious.push(ip);
+      }
+    }
+    return suspicious;
+  }
+
+  clearOldLogs(daysToKeep: number = 30): void {
+    const cutoffTime = Date.now() - (daysToKeep * 24 * 60 * 60 * 1000);
+    this.events = this.events.filter(event => event.timestamp > cutoffTime);
+  }
+
+  getActivityByIP(ip: string): number {
+    return this.ipActivity.get(ip) || 0;
+  }
+
+  clear(): void {
+    this.events = [];
+    this.ipActivity.clear();
+  }
+}
+
+export class SecurityLogger {
+  private logger: InMemorySecurityLogger;
+
+  constructor() {
+    this.logger = new InMemorySecurityLogger();
+  }
+
+  logEvent(event: Omit<SecurityEvent, 'timestamp'>): void {
+    this.logger.logEvent(event);
+  }
+
+  getRecentLogs(limit?: number): SecurityEvent[] {
+    return this.logger.getRecentLogs(limit);
+  }
+
+  getSuspiciousIPs(threshold?: number): string[] {
+    return this.logger.getSuspiciousIPs(threshold);
+  }
+
+  clearOldLogs(daysToKeep?: number): void {
+    this.logger.clearOldLogs(daysToKeep);
+  }
+
+  getActivityByIP(ip: string): number {
+    return this.logger.getActivityByIP(ip);
+  }
+
+  clear(): void {
+    this.logger.clear();
+  }
+}