Styjun

I've been struggling with a simple problem for hours now. I am working on a desktop application (a wallet) which needs a seed phrase to operate.
Naturally, the seed needs to be encrypted with a password and stored into a config file. I've found Jasypt which enables me to encrypt a String easily but apparently Jaspyt's PBEStringencryptor is supposed to be unsafe/deprecated. Since there's only one password, salting it wouldn't make any sense (would it?).
I've found many other methods on stackoverflock but I keep saying experts showing up and claiming how unsecure method x is.

To sum up my question: since I am only dealing with a single seed phrase, would using Jasypt's Stringencryptor be sufficient or should I use a different method?

The reason you are struggling to find a secure solution is probably that there is no secure solution that works in general.

Let me restate the problem that I think you are trying to solve:

1. Your application needs a "secret" to operate.


2. You cannot trust the user. (If you could, then you could in theory get the user to supply the secret each time they use the system.)


3. 
   

   You cannot rely on operating system access control to keep the "secret" safe, because of one or more of the following:

   
   
   
   • the operating system is inadequate or buggy
   
   
   • you don't trust the operators / administrators
   
   
   • you can't be sure that the system hasn't been hacked, or
   
   
   • the system is not physically secured. (If someone can get undetected physical access to the hardware for long enough, they can circumvent OS security.)
   
   

Given the above assumptions, there is no secure solution. No matter what your application code does, it is possible for someone with sufficient OS-level privilege (assigned properly, or acquired nefariously) to watch what your code is doing and intercept the secret.

So what is the solution?

• If you can assume that the platform is secure and the operators are trusted, there are technical ways to keep the secret secure ... from a non-privileged user.




• There are mitigations for some kinds of security attacks. For example, you could use a Hardware Security Module to hold the secret so that it doesn't need to be stored in the file system.




• Otherwise ... run the software on your (secure) infrastructure rather than the user's PC or your customer's servers.

seed needs to be encrypted with a password and stored into a config file..

Seems you are correct, the most reasonable way to encrypt the seed would be using some sort of password based encryption (PBE..).

Since there's only one password, salting it wouldn't make any sense (would it?).

you are storing the encrypted seed value itself, so in this case you may be ok with some application-wide static salt

PBEStringencryptor is supposed to be unsafe/deprecated.
would using Jasypt's Stringencryptor be sufficient

I am not aware of Jasyp being unsecure, it depends more on used parameters (any reference?). I usually use pure Java with standard PBKDF2 a few examples. However, Jasyp makes encryption done properly without deeper knowledge. The problem with cryptography is that it's easy to completely break security just using wrong set of parameters or using it wrong way. If you are just starting, using PBEStringencryptor may be safer option.

Someone mentioned using a hardware module (e. g. smartcard, TPM,.. ), could be safer, but less portable

I'am not an Java developer but as per described, what I would do in your case is to use asymmetric encryption of your seed with the desired password before storing it into a config file.

You could use Rivest Shamir Adleman (RSA), Elliptic Curve Cryptography (ECC) to name a few algorithms.

Cheers