I am trying to encrypt third party passwords and decrypt when I needed. I wonder if there are any standard solution to mix password with a random salt for each password independently similarly how BCrypt does it?
Thanks for any help!
There is PBKDF2 which is the password based key derivation function used in the Password Based Encryption (PBE) standards, also known as PKCS#5 and standardized in RFC 2898. Both Java and .NET contain implementations of this scheme out of the box.
Related
We are currently implementing our authorization to a restricted resource by encrypting specific information and the password given to create a token using AES/CBC/PKCS5Padding encryption with a 128bit private key known only to the server.
Inside this token we place
hash of password(sha-512 and a random salt of 64 bytes)
expiry date
valid flag (boolean)
creation date timestamp
The server then encrypts this information using its private key and passes it to the client.
The client requests the restricted resource and presents this token to the server which decrypts it and validates the contents to provide access to a restricted resource.
We wish to do it this way to avoid keeping information regarding issued tokens on our server to avoid potential resource limitations.
Since I am not a security expert any help showing possible vulnerabilities or why this is a bad idea would be much appreciated.
Just send the hashed version for comparison.
Just using a hash function is not sufficient and just adding a salt does little to improve the security. Instead iterate over an HMAC with a random salt for about a 100ms duration and save the salt with the hash. Use functions such as PBKDF2 (aka Rfc2898DeriveBytes), password_hash/password_verify, Bcrypt and similar functions. The point is to make the attacker spend a lot of time finding passwords by brute force. Protecting your users is important, please use secure password methods.
See Toward Better Password Requirements by Jim Fenton.
[DRAFT NIST Special Publication 800-63B Digital Authentication Guideline](
https://pages.nist.gov/800-63-3/sp800-63b.html)
NIST’s new password rules – what you need to know:
https://nakedsecurity.sophos.com/2016/08/18/nists-new-password-rules-what-you-need-to-know/ by Sophos
I hear about all these websites getting hacked with sql injections and stuff. What's preventing them from encrypting the hashes with a 32 character string? If I were a hacker and I managed to get the database and I came across encrypted hashes I would not be able to do anything with the database as I do not know the encryption algorithm and the key.
As long as the key being stored securly everyones account would be safe.
Your idea of encrypting the hashes will indeed improve the security of the users password, but you should understand what exactly you are solving with this measure and what not.
First and most important, encryption on passwords is usually frowned upon, because it is a weak protection. If an attacker has the key, he can instantly discover all passwords. So the encryption does not relieve you from properly hash passwords with a slow algorithm like BCrypt, SCrypt, PBKDF2 or Argon2.
But your question was about encrypting the hashes. There is a case where even properly hashed and salted passwords can be recovered easily. If the user has choosen a very weak password, a dictionary attack will reveal them very fast anyway. If the hashes are encrypted though, the attacker needs the key, before he can start with the dictionary. This leads us to the following situation:
Encrypting the hashes will protect weak passwords, as long as the key stays secret. This is always the case when the attacker has no privileges on the server, examples are SQL-injection, disregarded servers, backups, ... I tried to describe this at the end of my tutorial about safely storing passwords.
I have a .net application that stores hashed passwords in a sql server database.
The passwords are hashed using a salt that gets stored in the database with the hashed passwords.
As an extra layer of security, I hash the hashed password with another sitewide secret key that is not stored on the database server for security reasons. As the system is load balanced, where should I store the sitewide secret key? Store a copy of it in the config of each of my .net applications (same value on all servers).
Second question is, what is the recommended hashing mechanism for storing passwords?
I tend to use bcrypt storing passwords. The .NET implementation of it is BCrypt.NET as it doesn't come in the .NET framework at this point. You do not want to use a general purpose hash function like MD5. Another common algorithm is PBKDF2, but I have not personally used it in .NET.
I'm encrypting some data that needs to stay on the client, and so will the Salt, Key and IV. Is there a standard way of handling this data on the client to prevent people from discovering it and encryption your data?
I can think of plenty of things to obscure them, but there must be an industry standard way of dealing with this issue.
There's no additional security risk if the IV and salt are known. IV's are safe to store in the clear, and salts are to help prevent precomputation and rainbow tables.
So you're really just talking about the key. There's a couple solutions, each with it's own tradeoffs. In your question, you only mention you need to encrypt data on the client. Does the client not need to decrypt?
If this is a Windows client, you can use the Data Protection API to protect the key under the users credentials.
Protect the key with a passphrase. If you don't mind entering a passphrase each time the client needs the key, this can offer reasonable protection, and it's supported in most cryptosystems like OpenPGP.
If the client only needs to encrypt, you can use a hybrid approach with public keys (like OpenPGP). In this case, you only store the public key on the client, and the private key somewhere safe. When you encrypt data, you'll generate a random symmetric key, and encrypt that under the client's public key. Now if someone compromises the machine, they won't be able to decrypt any of the session keys.
Use specialized hardware like a hardware security module or smart card. This is the most expensive route, but depending on your threat model might be viable.
Given a site that uses the default ASP.NET Membership Provider and the membership password format is configured to use hashing and the hash algorithm is SHA1 (the default; same one used by LinkedIn) and assuming the membership database is breached, are there any additional steps that can be taken to further mitigate exploitation of said data?
From quickly looking at the membership schema, passwords seem to utilize a salt key. Is this measure sufficient?
To make things short: for storing passwords, you should never go with MD5, SHA1, SHA256, SHA512, SHA-3, etc... bcrypt is the only safe way to store a password.
Here is the why of the affirmation above:
Since my question a while back
Is this the way to salt and store a Password in Db?
I started to use BCrypt as my password hashing code, and from what I keep reading, even if you get hold of the users table, it is pretty difficult from that get the plain text of the storage password.
I use this in my Custom Membership Provider so I get to host my own passwords.
From the blog post:
Why BCrypt? Most popular password storage schemes are based on fast hashing algorithms such as MD5 and SHA-1. BCrypt is a computationally expensive adaptive hashing scheme which utilizes the Blowfish block cipher. It is ideally suited for password storage, as its slow initialization time severely limits the effectiveness of brute force password cracking attempts. How much overhead it adds is configurable (that's the adaptive part), so the computational resources required to test a password candidate can grow along with advancements in hardware capabilities.
From codahale.com you can also read How to safely store a password as well...
By the way, BCrypt project is on Codeplex