It is essential to store passwords in a way that prevents them from being obtained by an attacker even if the application or database is compromised. The majority of modern languages and frameworks provide built-in functionality to help store passwords safely.
After an attacker has acquired stored password hashes, they are always able to brute force hashes offline. As a defender, it is only possible to slow down offline attacks by selecting hash algorithms that are as resource intensive as possible.
This cheat sheet provides guidance on the various areas that need to be considered related to storing passwords. In short:
- Use Argon2id with a minimum configuration of 15 MiB of memory, an iteration count of 2, and 1 degree of parallelism.
- If Argon2id is not available, use scrypt with a minimum CPU/memory cost parameter of (2^16), a minimum block size of 8 (1024 bytes), and a parallelization parameter of 1.
- For legacy systems using bcrypt, use a work factor of 10 or more and with a password limit of 72 bytes.
- If FIPS-140 compliance is required, use PBKDF2 with a work factor of 310,000 or more and set with an internal hash function of HMAC-SHA-256.
- Consider using a pepper to provide additional defense in depth (though alone, it provides no additional secure characteristics).
Hashing vs Encryption¶
Hashing and encryption both provide ways to keep sensitive data safe. However, in almost all circumstances, passwords should be hashed, NOT encrypted.
Hashing is a one-way function (i.e., it is impossible to "decrypt" a hash and obtain the original plaintext value). Hashing is appropriate for password validation. Even if an attacker obtains the hashed password, they cannot enter it into an application's password field and log in as the victim.
Encryption is a two-way function, meaning that the original plaintext can be retrieved. Encryption is appropriate for storing data such as a user's address since this data is displayed in plaintext on the user's profile. Hashing their address would result in a garbled mess.
In the context of password storage, encryption should only be used in edge cases where it is necessary to obtain the original plaintext password. This might be necessary if the application needs to use the password to authenticate with another system that does not support a modern way to programmatically grant access, such as OpenID Connect (OIDC). Where possible, an alternative architecture should be used to avoid the need to store passwords in an encrypted form.
For further guidance on encryption, see the Cryptographic Storage Cheat Sheet.
How Attackers Crack Password Hashes¶
Although it is not possible to "decrypt" password hashes to obtain the original passwords, it is possible to "crack" the hashes in some circumstances.
The basic steps are:
- Select a password you think the victim has chosen (e.g.
- Calculate the hash
- Compare the hash you calculated to the hash of the victim. If they match, you have correctly "cracked" the hash and now know the plaintext value of their password.
This process is repeated for a large number of potential candidate passwords. Different methods can be used to select candidate passwords, including:
- Lists of passwords obtained from other compromised sites
- Brute force (trying every possible candidate)
- Dictionaries or wordlists of common passwords
While the number of permutations can be enormous, with high speed hardware (such as GPUs) and cloud services with many servers for rent, the cost to an attacker is relatively small to do successful password cracking especially when best practices for hashing are not followed.
Strong passwords stored with modern hashing algorithms and using hashing best practices should be effectively impossible for an attacker to crack. It is your responsibility as an application owner to select a modern hashing algorithm.
Password Storage Concepts¶
A salt is a unique, randomly generated string that is added to each password as part of the hashing process. As the salt is unique for every user, an attacker has to crack hashes one at a time using the respective salt rather than calculating a hash once and comparing it against every stored hash. This makes cracking large numbers of hashes significantly harder, as the time required grows in direct proportion to the number of hashes.
Salting also protects against an attacker pre-computing hashes using rainbow tables or database-based lookups. Finally, salting means that it is impossible to determine whether two users have the same password without cracking the hashes, as the different salts will result in different hashes even if the passwords are the same.
Modern hashing algorithms such as Argon2id, bcrypt, and PBKDF2 automatically salt the passwords, so no additional steps are required when using them.
A pepper can be used in addition to salting to provide an additional layer of protection. The purpose of the pepper is to prevent an attacker from being able to crack any of the hashes if they only have access to the database, for example, if they have exploited a SQL injection vulnerability or obtained a backup of the database.
One of several peppering strategies is to hash the passwords as usual (using a password hashing algorithm) and then HMAC or encrypt the hashes with a symmetrical encryption key before storing the password hash in the database, with the key acting as the pepper. Peppering strategies do not affect the password hashing function in any way.
- The pepper is shared between stored passwords, rather than being unique like a salt.
- Unlike a password salt, the pepper should not be stored in the database.
- Peppers are secrets and should be stored in "secrets vaults" or HSMs (Hardware Security Modules).
- Like any other cryptographic key, a pepper rotation strategy should be considered.
The work factor is essentially the number of iterations of the hashing algorithm that are performed for each password (usually, it's actually
2^work iterations). The purpose of the work factor is to make calculating the hash more computationally expensive, which in turn reduces the speed and/or increases the cost for which an attacker can attempt to crack the password hash. The work factor is typically stored in the hash output.
When choosing a work factor, a balance needs to be struck between security and performance. Higher work factors will make the hashes more difficult for an attacker to crack but will also make the process of verifying a login attempt slower. If the work factor is too high, this may degrade the performance of the application and could also be used by an attacker to carry out a denial of service attack by making a large number of login attempts to exhaust the server's CPU.
There is no golden rule for the ideal work factor - it will depend on the performance of the server and the number of users on the application. Determining the optimal work factor will require experimentation on the specific server(s) used by the application. As a general rule, calculating a hash should take less than one second.
Upgrading the Work Factor¶
One key advantage of having a work factor is that it can be increased over time as hardware becomes more powerful and cheaper.
The most common approach to upgrading the work factor is to wait until the user next authenticates and then to re-hash their password with the new work factor. This means that different hashes will have different work factors and may result in hashes never being upgraded if the user doesn't log back into the application. Depending on the application, it may be appropriate to remove the older password hashes and require users to reset their passwords next time they need to login in order to avoid storing older and less secure hashes.
Password Hashing Algorithms¶
There are a number of modern hashing algorithms that have been specifically designed for securely storing passwords. This means that they should be slow (unlike algorithms such as MD5 and SHA-1, which were designed to be fast), and how slow they are can be configured by changing the work factor.
Websites should not hide which password hashing algorithm they use. If you utilize a modern password hashing algorithm with proper configuration parameters, it should be safe to state in public which password hashing algorithms are in use and be listed here.
The main three algorithms that should be considered are listed below:
Argon2 is the winner of the 2015 Password Hashing Competition. There are three different versions of the algorithm, and the Argon2id variant should be used, as it provides a balanced approach to resisting both side-channel and GPU-based attacks.
Rather than a simple work factor like other algorithms, Argon2id has three different parameters that can be configured. Argon2id should use one of the following configuration settings as a base minimum which includes the minimum memory size (m), the minimum number of iterations (t) and the degree of parallelism (p).
- m=37 MiB, t=1, p=1
- m=15 MiB, t=2, p=1
Both of these configuration settings are equivalent in the defense they provide. The only difference is a trade off between CPU and RAM usage.
scrypt is a password-based key derivation function created by Colin Percival. While new systems should consider Argon2id for password hashing, scrypt should be configured properly when used in legacy systems.
Like Argon2id, scrypt has three different parameters that can be configured. scrypt should use one of the following configuration settings as a base minimum which includes the minimum CPU/memory cost parameter (N), the blocksize (r) and the degree of parallelism (p).
- N=2^16 (64 MiB), r=8 (1024 bytes), p=1
- N=2^15 (32 MiB), r=8 (1024 bytes), p=2
- N=2^14 (16 MiB), r=8 (1024 bytes), p=4
- N=2^13 (8 MiB), r=8 (1024 bytes), p=8
- N=2^12 (4 MiB), r=8 (1024 bytes), p=15
These configuration settings are equivalent in the defense they provide. The only difference is a trade off between CPU and RAM usage.
The bcrypt password hashing function should be the second choice for password storage if Argon2id is not available or PBKDF2 is required to achieve FIPS-140 compliance.
The work factor should be as large as verification server performance will allow, with a minimum of 10.
bcrypt has a maximum length input length of 72 bytes for most implementations. To protect against this issue, a maximum password length of 72 bytes (or less if the implementation in use has smaller limits) should be enforced when using bcrypt.
An alternative approach is to pre-hash the user-supplied password with a fast algorithm such as SHA-256, and then to hash the resulting hash with bcrypt (i.e.,
bcrypt(base64(hmac-sha256(data:$password, key:$pepper)), $salt, $cost)). This is a dangerous (but common) practice that should be avoided due to password shucking and other issues when combining bcrypt with other hash functions.
PBKDF2 requires that you select an internal hashing algorithm such as an HMAC or a variety of other hashing algorithms. HMAC-SHA-256 is widely supported and is recommended by NIST.
The work factor for PBKDF2 is implemented through an iteration count, which should set differently based on the internal hashing algorithm used.
- PBKDF2-HMAC-SHA1: 720,000 iterations
- PBKDF2-HMAC-SHA256: 310,000 iterations
- PBKDF2-HMAC-SHA512: 120,000 iterations
These configuration settings are equivalent in the defense they provide.
When PBKDF2 is used with an HMAC, and the password is longer than the hash function's block size (64 bytes for SHA-256), the password will be automatically pre-hashed. For example, the password "This is a password longer than 512 bits which is the block size of SHA-256" is converted to the hash value (in hex) fa91498c139805af73f7ba275cca071e78d78675027000c99a9925e2ec92eedd. A good implementation of PBKDF2 will perform this step before the expensive iterated hashing phase, but some implementations perform the conversion on each iteration. This can make hashing long passwords significantly more expensive than hashing short passwords. If a user can supply very long passwords, there is a potential denial of service vulnerability, such as the one published in Django in 2013. Manual pre-hashing can reduce this risk but requires adding a salt to the pre-hash step.
Upgrading Legacy Hashes¶
For older applications built using less secure hashing algorithms such as MD5 or SHA-1, these hashes should be upgraded to modern password hashing algorithms as described above. When the user next enters their password (usually by authenticating on the application), it should be re-hashed using the new algorithm. It would also be good practice to expire the users' current password and require them to enter a new one so that any older (less secure) hashes of their password are no longer useful to an attacker.
However, this approach means that old (less secure) password hashes will be stored in the database until the user logs in. Two main approaches can be taken to avoid this dilemma.
One method is to expire and delete the password hashes of users who have been inactive for an extended period and require them to reset their passwords to login again. Although secure, this approach is not particularly user-friendly. Expiring the passwords of many users may cause issues for support staff or may be interpreted by users as an indication of a breach.
An alternative approach is to use the existing password hashes as inputs for a more secure algorithm. For example, if the application originally stored passwords as
md5($password), this could be easily upgraded to
bcrypt(md5($password)). Layering the hashes avoids the need to know the original password; however, it can make the hashes easier to crack. These hashes should be replaced with direct hashes of the users' passwords next time the user logs in.
Assume that whatever password hashing method is selected will have to be upgraded in the future. Ensure that upgrading your hashing algorithm is as easy as possible. For a transition period, allow for a mix of old and new hashing algorithms. Using a mix of hashing algorithms is easier if the password hashing algorithm and work factor are stored with the password using a standard format, for example, the modular PHC string format.
Ensure your hashing library is able to accept a wide range of characters and is compatible with all Unicode codepoints. Users should be able to use the full range of characters available on modern devices, in particular mobile keyboards. They should be able to select passwords from various languages and include pictograms. Prior to hashing the entropy of the user's entry should not be reduced. Password hashing libraries need to be able to use input that may contain a NULL byte.
To protect passwords, experts suggest using a strong and slow hashing algorithm like Argon2 or Bcrypt, combined with salt (or even better, with salt and pepper). (Basically, avoid faster algorithms for this usage.) To verify file signatures and certificates, SHA-256 is among your best hashing algorithm choices.What is Owasp Cheat Sheet Series? ›
The OWASP Cheat Sheet Series was created to provide a concise collection of high value information on specific application security topics. These cheat sheets were created by various application security professionals who have expertise in specific topics.Is SHA-512 still secure? ›
SHA-512 is still a very secure, and trust worthy algorithm that can be safety used in programs currently in development.Which technique is used commonly used for password storage? ›
Commonly used hashing algorithms include Message Digest (MDx) algorithms, such as MD5, and Secure Hash Algorithms (SHA), such as SHA-1 and the SHA-2 family that includes the widely used SHA-256 algorithm.What are four 4 best practices for passwords? ›
- Never reveal your passwords to others. ...
- Use different passwords for different accounts. ...
- Use multi-factor authentication (MFA). ...
- Length trumps complexity. ...
- Make passwords that are hard to guess but easy to remember.
- Complexity still counts. ...
- Use a password manager.
Definition. The Open Web Application Security Project (OWASP) is a nonprofit foundation dedicated to improving software security.What is OWASP checklist? ›
OWASP based Web Application Security Testing Checklist is an Excel based checklist which helps you to track the status of completed and pending test cases.Is the cheat sheet a series? ›
The Cheat Sheet is Sarah's newest addition to her series of fantastic romantic comedies. One of my favorite things about Sarah's stories is how relatable her heroines are.Has SHA-256 been cracked? ›
As we mentioned earlier, no one has been able to crack SHA 256 to date, and it's used in some of the most secure networks in the world.Should I use SHA512 or SHA-256? ›
The reason why SHA-512 is faster than SHA-256 on 64-bit machines is that has 37.5% less rounds per byte (80 rounds operating on 128 byte blocks) compared to SHA- 256 (64 rounds operating on 64 byte blocks), where the operations use 64-bit integer arithmetic.
TL;DR; SHA1, SHA256, and SHA512 are all fast hashes and are bad for passwords. SCRYPT and BCRYPT are both a slow hash and are good for passwords. Always use slow hashes, never fast hashes.What are 3 types password cracking methods? ›
- Phishing. Phishing is when a hacker posing as a trustworthy party sends you a fraudulent email, hoping you will reveal your personal information voluntarily. ...
- Man-in-the-Middle Attack. ...
- Brute Force Attack. ...
- Dictionary Attack. ...
- Credential Stuffing. ...
There are three ways to store passwords for later use in authenticating users: You can store the password itself in plaintext. You can encrypt the password and store the ciphertext. You can create a one-way hash of the password and store that hash in the database.Where is the most secure place to store passwords? ›
The best way to safely generate, store, and keep track of your passwords is to use a password manager app like LastPass. A password manager encrypts your passwords and stores them in a vault locked behind a master password, as well as advanced protective measures like multifactor authentication.What is the hardest encryption to crack? ›
AES 256-bit encryption is the strongest and most robust encryption standard that is commercially available today. While it is theoretically true that AES 256-bit encryption is harder to crack than AES 128-bit encryption, AES 128-bit encryption has never been cracked.What is the most unbreakable encryption? ›
There is only one known unbreakable cryptographic system, the one-time pad, which is not generally possible to use because of the difficulties involved in exchanging one-time pads without their being compromised. So any encryption algorithm can be compared to the perfect algorithm, the one-time pad.Which are 4 key pillars of cryptography? ›
- Confidentiality: keep communication private.
- Integrity: detect unauthorized alteration to communication.
- Authentication: confirm identity of sender.
- Authorization: establish level of access for trusted parties.
- Non-repudiation: prove that communication was received.
I call the above two rules combined as “8 4 Rule” (Eight Four Rule): 8 = 8 characters minimum length. 4 = 1 lower case + 1 upper case + 1 number + 1 special character.What are 5 rules for a strong password? ›
- At least 12 characters (required for your Muhlenberg password)—the more characters, the better.
- A mixture of both uppercase and lowercase letters.
- A mixture of letters and numbers.
- Inclusion of at least one special character, e.g., ! @ # ? ]
And once you finally select a password, its strength needs to observe these parameters: Length of the password – preferably over 12 characters. Complexity of the password – must contain letters (upper and lower case), numbers, and symbols and have a minimum number of each. Contain no repetitive characters.
3. Injection. Injection vulnerabilities can occur when a query or command is used to insert untrusted data into the interpreter via SQL, OS, NoSQL, or LDAP injection.Is OWASP still relevant? ›
There is some merit to these arguments, but the OWASP Top 10 is still the leading forum for addressing security-aware coding and testing. It's easy to understand, it helps users prioritise risk, and its actionable. And for the most part, it focuses on the most critical threats, rather than specific vulnerabilities.What is OWASP methodology? ›
OWASP pen testing describes the assessment of web applications to identify vulnerabilities outlined in the OWASP Top Ten. An OWASP pen test is designed to identify, safely exploit and help address these vulnerabilities so that any weaknesses discovered can be quickly addressed.What is a secure coding checklist? ›
The checklist for secure coding is below: Authentication with secured password. Session Management with complete user details. Access Control and manage with proper verification of user. File Uploading would be specific to the context of the page.How do I use OWASP? ›
Running an Automated Scan
Start ZAP and click the Quick Start tab of the Workspace Window. Click the large Automated Scan button. In the URL to attack text box, enter the full URL of the web application you want to attack. Click the Attack.
A book series can be two books or 50 books and counting. It all depends on what type of story you're telling and how long it takes you to tell that story.Is The Cheat Sheet dual perspective? ›
Just as Sarah's other RomComs 𝙏𝙃𝙀 𝘾𝙃𝙀𝘼𝙏 𝙎𝙃𝙀𝙀𝙏 is a dual perspective book and it doesn't take long before it is revealed Nathan would move heaven and earth for Bree.How do you structure a cheat sheet? ›
Group similar information into sections. Once you've identified all the information you need for your cheat sheet, organize that information into categories. You should group together similar pieces of information so the cheat sheet is easy to read. Scan the items on your list and see what information groups together.Can NSA break SHA 256? ›
It is a cryptographically secure hash function. There is NO WAY to recover the original data from the hash alone. There is just not enough bits available. So, no, NSA cannot recover the original data from the SHA256 hash.Can you brute-force SHA256? ›
First developed in 1993 the SHA256 algorithm, as far back as 2005 the it was considered insecure against "well funded attackers". The increase in computing power has allowed brute calculations of SHA256 into the billions per second with common consumer hardware.
AES 256 is virtually impenetrable using brute-force methods. While a 56-bit DES key can be cracked in less than a day, AES would take billions of years to break using current computing technology. Hackers would be foolish to even attempt this type of attack. Nevertheless, no encryption system is entirely secure.Why is SHA-1 no longer secure? ›
It is supposed to be unique and non-reversible. If a weakness is found in a hash function that allows for two files to have the same digest, the function is considered cryptographically broken, because digital fingerprints generated with it can be forged and cannot be trusted.Why is Sha 3 not used? ›
The number one reason why the world didn't move to SHA-3 is because almost none of the world's software or hardware supported it.Which is better AES or SHA? ›
AES: It is a symmetric cryptography, i.e. it uses same key for both encryption and decryption. SHA: It is a hash algorithm, i.e. one way encryption. So that it gives no way for decryption.Why is SHA-256 not secure? ›
For example, a 512-bit string of data would be transformed into a 256-bit string through SHA-256 hashing. In cryptographic hashing, the hashed data is modified in a way that makes it completely unreadable. It would be virtually impossible to convert the 256-bit hash mentioned above back to its original 512-bit form.Which is better AES 256 or SHA-256? ›
The main difference between AES and SHA is that AES suits in symmetric key shape and offers a longer key (safer) than DES. It offers message encryption, a lot quicker than uneven keys including RSA. at the same time as SHA hashing is used to generate message digest to affirm message integrity.Which is better SHA-256 or MD5? ›
The SHA-256 algorithm returns hash value of 256-bits, or 64 hexadecimal digits. While not quite perfect, current research indicates it is considerably more secure than either MD5 or SHA-1. Performance-wise, a SHA-256 hash is about 20-30% slower to calculate than either MD5 or SHA-1 hashes.Which tool is best for password cracking? ›
- Burp Suite.
- John the Ripper.
Is Python good for hacking? Python ranks as the number one popular programming language in the world, according to 2022 Tiobe Index data. It's also a popular language with hackers because it provides powerful and easy-to-use libraries enabling them to work quickly.What are the three rules for passwords? ›
- Rule 1 – Use more than eight characters. ...
- Rule 2 – Always use different passwords for different platforms. ...
- Rule 3 – Use a password manager. ...
- Password policies for businesses. ...
- Training your staff.
- What Is the Most Secure Way to Keep Passwords? Using a password manager is the best way to keep your passwords out of the hands of cybercriminals.
- How Can I Securely Store My Passwords for Free? Many password managers include free plans and free trials. Bitwarden is the best free password manager on the market.
- Use a mix of alphabetical and numeric characters.
- Use a mixture of upper- and lowercase; passwords are case sensitive.
- Use symbols if the system allows (spaces shouldn't be used as some applications may trim them away)
You can enable Advanced Encryption Standard (AES) password encryption so that your passwords are more secure in your configuration files and properties files for the server environment. Currently, WebSphere® Application Server supports AES-128 encryption.What is the most secure password hashing algorithm? ›
To the time of writing, SHA-256 is still the most secure hashing algorithm out there. It has never been reverse engineered and is used by many software organizations and institutions, including the U.S. government, to protect sensitive information.Which algorithm is used to encrypt password? ›
Passwords are encrypted by the MD5 hash algorithm before they are stored in the directory. Passwords are encrypted by the SHA-1 encrypting algorithm before they are stored in the directory.Can AES 256 be cracked? ›
AES 256 is virtually impenetrable using brute-force methods. While a 56-bit DES key can be cracked in less than a day, AES would take billions of years to break using current computing technology. Hackers would be foolish to even attempt this type of attack.Is RSA or AES better? ›
The Advance Encryption Standard (AES) cipher text method is a more accurate and elegant cryptographic method. According to testing results and the text files used, it has been concluded that the AES algorithm outperforms the Data Encryption Standard (DES) and RSA algorithms [6,7].What is the strongest password manager? ›
- Best Overall: LastPass.
- Best for Extra Security Features: Dashlane.
- Best Multi-Device Platform: LogMeOnce.
- Best Free Option: Bitwarden.
- Best for New Users: RememBear.
- Best for Families: 1Password.
- Best Enterprise-Level Manager: Keeper.
SHA 256 converts data into fixed-length, virtually irreversible hash values, and is mainly used to verify the authenticity data. As we mentioned earlier, no one has been able to crack SHA 256 to date, and it's used in some of the most secure networks in the world.What are the 3 types of encryption keys? ›
Symmetric, or secret key encryption, uses a single key for both encryption and decryption. Symmetric key encryption is used for encrypting large amounts of data efficiently. 256-bit AES keys are symmetric keys. Asymmetric, or public/private encryption, uses a pair of keys.
AES 256-bit encryption is the strongest and most robust encryption standard that is commercially available today.