Complete Guide to PIN Codes: Security & Best Practices
Introduction to PIN Codes
Personal Identification Numbers (PINs) have become an essential part of our daily security routine. From banking to smartphones, PIN codes serve as a simple yet effective first line of defense against unauthorized access to sensitive accounts and devices.
Originally introduced in the 1960s for use with ATM machines, PINs were designed to provide a balance between security and convenience. While passwords are generally more secure due to their complexity, PINs offer quick access when frequent authentication is needed or when typing complex passwords would be impractical.
Despite their simplicity, a randomly generated 6-digit PIN has 1 million possible combinations, making it reasonably secure against brute force attacks when proper attempt limits are in place.
Types of PINs and Their Uses
4-Digit Numeric PINs
The most common PIN format, offering 10,000 possible combinations.
- Bank cards and ATMs
- Smartphone unlock codes
- Credit card verification
- Simple door access systems
6-Digit Numeric PINs
Enhanced security with 1,000,000 possible combinations.
- Modern smartphone security
- Banking applications
- Two-factor authentication
- High-security building access
Alphanumeric PINs
Including letters and numbers dramatically increases security.
- High-security accounts
- Corporate security systems
- Encryption keys
- Military and government systems
Multi-Factor PINs
PINs combined with other authentication methods.
- Banking transactions
- Corporate access
- Healthcare data access
- Critical infrastructure systems
PIN Security Best Practices
Choose Truly Random PINs
Avoid predictable patterns such as:
- Sequential numbers (1234, 6789)
- Repeated digits (1111, 5555)
- Simple patterns (1357, 2468, 1397)
- Years and dates (1990, 0620)
- Randomly generated numbers (8146, 9372)
- Non-sequential combinations (2817, 5940)
- PINs without obvious patterns
Use Different PINs for Different Services
Just like passwords, PIN reuse is a significant security risk. If a criminal obtains one of your PINs, they will try it on all your accounts.
Consider using different PIN codes for:
- Bank cards and financial services
- Mobile devices
- Door codes and physical access
- Vehicle systems
Longer is Stronger
When possible, opt for longer PINs:
Protect Your PIN
- Shield your PIN when entering it in public
- Never share your PIN, even with family members
- Don't store PINs in easily accessible places
- Be aware of shoulder surfers when entering PINs
- Check for skimming devices when using ATMs
Consider Memorable Methods
If you need to create memorable but secure PINs, try these methods:
- Use a pattern on the numeric keypad that only makes sense visually to you
- Convert a word into numbers using the keypad (e.g., "CASH" = 2274)
- Use a mathematical formula that only you know (e.g., your birth year minus your birth month × 2)
- Take digits from multiple important dates and combine them in a specific order
PINs vs. Passwords: When to Use Each
When to Choose a PIN
- When you need frequent, quick access
- On devices with limited input options
- When the system has built-in lockouts after failed attempts
- For secondary authentication (in addition to another method)
When to Choose a Password
- For primary online accounts
- When maximum security is required
- When the system doesn't limit incorrect attempts
- For accounts containing sensitive personal or financial information
Frequently Asked Questions
A 4-digit PIN offers 10,000 possible combinations, which is sufficient security for systems that limit incorrect attempts or implement timeouts after failed attempts. However, for sensitive accounts or systems without such protections, a 6 or 8-digit PIN provides significantly better security.
The best approaches include:
- Using a secure password manager that supports storing PINs
- Creating a system where you derive each PIN based on the service (using a formula only you know)
- For physical storage, consider using a coded or encrypted system rather than writing down the actual PINs
For high-security applications like banking PINs, changing them every 6-12 months is good practice. Change them immediately if:
- You suspect someone has seen you enter it
- You've used your PIN on a suspicious device
- The organization that issued the PIN has experienced a security breach
While biometric authentication (fingerprints, face recognition) is becoming more common, PINs still serve as an essential backup method. Many security systems use multi-factor authentication where biometrics are used in conjunction with PINs rather than replacing them entirely. This provides better security through multiple verification methods.
For low-security applications, this may be acceptable. However, for financial PINs or those protecting sensitive information, it's generally not recommended to allow automatic storage. If you choose to do so, ensure your device is secured with strong protection (password/biometrics) and encrypted storage.