I'm working on encrypting sensitive fields in a database, specifically user information like email addresses. I need to ensure that users can't create multiple accounts with the same email, which means I need a way to check for existing accounts without decrypting the information every time. I'm considering storing both an encrypted email and a hash of that email in separate fields. The idea is that when a new user signs up, I can hash the email they input and check if that hash already exists. I'm a bit confused though—if I store the hash, can I still claim the email field is encrypted? Also, is it true that different email addresses could potentially result in the same hash, making this method less reliable?
3 Answers
You're right to think about the implications of storing the hashed emails. If someone knows the hash algorithm and gets access to your database, they may be able to infer some info, especially for limited sets of data like political parties. That's why unique salts can be important. Using a unique salt for each user can add a layer of security as it makes it tougher to reverse even if the hash gets exposed. Still, if the field is encrypted, it's still considered encrypted, but you should also be cautious about how you're using those hashes.
Storing both an encrypted value and a hash is a common practice to index encrypted fields. Just keep in mind that while you can do this, the goal of encryption is to protect data from being read without the proper keys. If an attacker compromises your database, having both a hash and an encrypted value might give them some information—they could potentially brute force or guess hash values if they can match any common plaintext during a lookup.
Right, and always make sure to use secure hashing algorithms. If you're worried about collisions in your use case, consider implementing additional checks or using more robust hash functions.
A hash is not reversible like encryption, which means you can't get back to the original value once you hash it. So, if you're using an encrypted field and have a hash of the original value, the encrypted field still maintains its status as encrypted. It's more like using two different tools for security: hashing for verification and encryption for confidentiality.
However, as you mentioned, there's always a risk of hash collisions (where two different inputs yield the same hash). This isn't a big concern with strong hashes like SHA-256, but it can happen, especially with less secure methods. But if you only need to check for exact matches, hashes work well for that.
Yeah, and keep in mind that if you need to ensure uniqueness (like for emails), checking against a hash makes sense. Just remember that hashing isn't for encryption but serves a different purpose in verification!
Exactly! Using salts greatly increases security but can complicate things like lookups. You could end up needing to hash against many salts to search effectively, so weigh your options carefully.