Password Generator

The Evolution of Password Security

Password security has evolved dramatically since the first computer passwords were implemented in the 1960s. Initially, passwords were stored in plaintext and often limited to 8 characters. Today, modern security standards recommend passwords of at least 12 characters, with no arbitrary complexity requirements or mandatory rotation policies.

The National Institute of Standards and Technology (NIST) revised its guidelines in Special Publication 800-63B, moving away from complex composition rules and frequent password changes. Instead, they now emphasize password length, checking against known compromised passwords, and implementing secure hashing algorithms with proper salting techniques.

The Mathematics Behind Password Strength

Password strength is fundamentally a mathematical concept based on entropy, which measures the unpredictability of a password. A password's entropy is calculated as log₂(R^L), where R is the size of the character set and L is the password length.

For example, a 12-character password using only lowercase letters (26 characters) has an entropy of approximately 56 bits (log₂(26^12)). Adding uppercase letters, numbers, and symbols increases the character set to around 94 characters, raising the entropy to approximately 78 bits for the same length.

This exponential relationship explains why password length is more important than complexity. Adding just one character to a password increases its strength more than adding a new character type. A 16-character password using only lowercase letters (75 bits of entropy) is stronger than a 12-character password using all character types (78 bits).

The Psychology of Password Creation

Despite knowing the importance of strong passwords, humans consistently create predictable passwords due to cognitive limitations. We tend to use familiar patterns, substitutions (e.g., 'a' to '@'), and personal references that are easier to remember but also easier to crack.

Research shows that when asked to create "random" passwords, users typically follow predictable patterns: a capitalized word, followed by a number (often a year), and ending with a special character. This knowledge is exploited by password cracking tools that use rule-based transformations on dictionary words.

The cognitive load of managing multiple complex passwords leads to password reuse, which presents a significant security risk. This psychological reality underscores the importance of password managers and multi-factor authentication as complementary security measures.

Best Practices

• Use passphrases: Consider using memorable phrases of 4+ random words instead of traditional passwords
• Implement multi-factor authentication: Even the strongest password is vulnerable if compromised; MFA provides an additional security layer
• Use unique passwords for each service: Password reuse is the most common cause of account compromise
• Employ a password manager: This allows you to use strong, unique passwords without memorizing them
• Check for compromised passwords: Use services like Have I Been Pwned to verify if your passwords have been exposed in data breaches
• Consider passwordless authentication: Where available, options like biometrics or security keys can be more secure than passwords

Common Misconceptions

Many users believe that adding complexity through character substitutions (e.g., replacing 'e' with '3') significantly increases password security. In reality, these substitutions follow predictable patterns and are accounted for in password cracking algorithms. A longer password using regular characters is typically more secure than a shorter one with complex substitutions.

Another misconception is that frequent password changes improve security. Research has shown that mandatory password rotation often leads to weaker passwords as users make minimal changes to remember their new passwords (e.g., adding a number at the end and incrementing it). This is why NIST no longer recommends periodic password changes unless there's evidence of compromise.

Finally, many users believe that "strong password" indicators on websites are reliable measures of password security. In reality, these meters vary widely in their assessment criteria, with many failing to properly evaluate password strength beyond basic composition rules.

Expert verification date: May 2025

Basic Usage

1. Adjust Password Length: Use the slider to set your desired password length (between 4 and 64 characters)
2. Select Character Types: Choose which character types to include in your password:
   • Uppercase letters (A-Z)
   • Lowercase letters (a-z)
   • Numbers (0-9)
   • Symbols (!@#$%^&*)
3. Set Additional Options:
   • Exclude similar characters (i, l, 1, L, o, 0, O) to prevent confusion
   • Exclude ambiguous characters ({}, [], (), /, etc.) that may cause issues in some systems
4. Generate Passwords: Click the "Generate Passwords" button to create new passwords based on your settings
5. Copy to Clipboard: Click the "Copy" button next to any password to save it to your clipboard

Advanced Features

• Multiple Passwords: Generate up to 10 passwords simultaneously for comparison
• Password Strength Indicator: Each password displays a strength rating (Very Weak, Weak, Moderate, Strong, Very Strong)
• Export to PDF: Download a PDF document containing your generated passwords and settings
• Persistent Settings: Your preferences are saved between sessions for convenience

Example Use Cases

Creating a Strong Master Password

1. Set length to at least 16 characters
2. Enable all character types (uppercase, lowercase, numbers, symbols)
3. Generate several options and choose one that's both strong and memorable
4. Consider using a password manager to store this master password securely

Generating Website Credentials

1. Set length to 12-16 characters
2. Check if the website has specific password requirements
3. If the site doesn't accept certain symbols, enable the "Exclude Ambiguous Characters" option
4. Generate and copy your new password
5. Update your password manager with the new credentials

Creating System Administrator Passwords

1. Set maximum length (64 characters) for critical systems
2. Enable all character types
3. Generate multiple options
4. Export to PDF for secure documentation
5. Store in an encrypted password manager

How secure are the passwords generated by this tool?

The passwords generated by this tool use JavaScript's built-in randomization functions to create unpredictable character sequences. When you select multiple character types (uppercase, lowercase, numbers, and symbols) and choose a length of 12 or more characters, the resulting passwords are highly resistant to brute force attacks and dictionary-based cracking attempts.

Are my generated passwords stored anywhere?

No. All password generation happens entirely in your browser. Your passwords and preferences are never sent to any server. The only data stored is your preference settings, which are saved in your browser's local storage for convenience between sessions. Generated passwords are not stored after you leave the page unless you explicitly save them.

What makes a password "strong" according to this tool?

Our strength assessment evaluates passwords based on two primary factors: length and character variety. A password receives points for:

• Length (1 point for 8+ characters, 2 points for 12+ characters)
• Character variety (up to 2 points for using different character types)

The resulting score (0-4) determines the strength rating from "Very Weak" to "Very Strong." This aligns with NIST guidelines that emphasize password length and complexity.

Why would I exclude similar or ambiguous characters?

Excluding similar characters (like i, l, 1, L, o, 0, O) reduces confusion when you need to manually type a password. This is especially useful for passwords you might need to share verbally or write down temporarily.

Excluding ambiguous characters (like {}, [], (), /, etc.) helps avoid issues with systems that may have special handling for these characters, particularly in command-line interfaces, configuration files, or older systems with character limitations.

How many passwords should I generate?

For most purposes, generating 3-5 passwords gives you enough options to choose one that balances security with memorability. For critical systems, generate more options and select the strongest one. Remember that using a different password for each service is more important than the specific password you choose.

Can I use these passwords with a password manager?

Absolutely! In fact, we recommend using a password manager to store your generated passwords securely. This allows you to use longer, more complex passwords without having to memorize them. The "Copy" button makes it easy to transfer your generated passwords directly to your password manager.

How often should I change my passwords?

Current security best practices from NIST no longer recommend regular password changes unless there's evidence of compromise. Instead, focus on creating strong, unique passwords for each service and using multi-factor authentication where available. If a service experiences a data breach, change that password immediately.

Official Standards

• NIST Special Publication 800-63B - Digital Identity Guidelines: Authentication and Lifecycle Management from the National Institute of Standards and Technology, providing comprehensive guidance on password security and management.
• OWASP Authentication Cheat Sheet - The Open Web Application Security Project's guidelines for implementing secure authentication mechanisms, including password security best practices.
• ISO/IEC 27001:2013 - Information security management systems standard that includes requirements for password management and authentication controls.

Academic Sources

• Florêncio, D., Herley, C., & Van Oorschot, P. C. (2014). Password portfolios and the finite-effort user: Sustainably managing large numbers of accounts. Proceedings of the 23rd USENIX Security Symposium. https://www.usenix.org/system/files/conference/usenixsecurity14/sec14-paper-florencio.pdf
• Ur, B., Noma, F., Bees, J., Segreti, S. M., Shay, R., Bauer, L., Christin, N., & Cranor, L. F. (2015). "I added '!' at the end to make it secure": Observing password creation in the lab. Proceedings of the Eleventh Symposium on Usable Privacy and Security (SOUPS). https://www.usenix.org/system/files/conference/soups2015/soups15-paper-ur.pdf
• Habib, H., Colnago, J., Melicher, W., Ur, B., Segreti, S., Bauer, L., Christin, N., & Cranor, L. (2017). Password creation in the presence of blacklists. Proceedings of the Workshop on Usable Security (USEC). https://www.ndss-symposium.org/wp-content/uploads/2017/09/usec2017_01_4_Habib_paper.pdf
• Bonneau, J. (2012). The science of guessing: Analyzing an anonymized corpus of 70 million passwords. IEEE Symposium on Security and Privacy. https://doi.org/10.1109/SP.2012.49

Online Resources

• Have I Been Pwned - A free resource to check if your email or password has been compromised in a data breach, maintained by security researcher Troy Hunt.
• Password Strength Checker by Kaspersky - An interactive tool that evaluates password strength and provides recommendations for improvement.
• Diceware Passphrase - A methodology for creating strong yet memorable passphrases using dice and word lists.
• NIST Password Guidelines Explained - A detailed explanation of the NIST password guidelines and their practical implications.
• Password Manager Reviews by Consumer Reports - Independent reviews of popular password managers to help users choose a secure solution.

Last verified: May 2025