Andrew, I've been using your functions successfully and happily for several months now. Something strange occurred a couple of days ago. I opened a file that contains a call to the encryption function, made no changes, and now I can't decrypt the data. The data is being stored in MySQL btw.

I've narrowed it down to the following facts.

1. The data can be encrypted and decrypted on the server prior to storing in MySQL.
2. Decryption fails when the data is retrieved from MySQL.
3. I'm using base64_encode prior to storing in the DB.
4. I'm using base64_decode when retrieving from the DB.
5. Data stored in the DB prior to opening the file is still decryptable using the pre-existing code.
6. Only new data is being affected.
7. I can successfully base64_encode, store, retrieve, and base64_decode data. The issue occurs only when I'm trying to encrypt the data prior to the base64_encode.

The issue seems to be that something is happening upon storing or retrieving the data. I've been trying to figure it out for about 2 days now. What could be happening? I've found some things pointing to character encoding that may be interfering, but I can't seem to figure out exactly how that may ( or may not ) be working against me. I'm hoping that you've seen this and it's a "Known Issue". Any help is appreciated.

This is a fantastically written and referenced article. I've been spending the past couple of days in my downtime just figuring out where to get started with mcrypt, in one fell swoop you gave me a beautiful starting point and the resources to understand it.

Just wanted to say, job well done :)

Glad to hear you sorted it out. Running it through base64 encode provides a nice representation of the raw binary ciphertext that can easily be passed around and stored. I'll wager to say you weren't writing the data to the file in binary mode and an EOL translation occurred.

Update #2:

Just as an aside, it is definitely the download process that is killing the ability to decrypt. I tried downloading a file and then simply moving it manually back to the server (not through an HTTP upload form) and it still died. At least we're narrowing down the problem.

@Andrew,

Thanks for the wicked fast reply. Here's how it goes:

User creates an encrypted file -> an sql dump is performed, that sql file is gzipped, and that gzipped file is encrypted using the following method:


The file is then downloaded using Content-Type: application/force-download and transfer encoding as binary. I'm thinking the problem occurs here because if the exact same sequence is performed but the file isn't downloaded, then decryption works perfect with the class as is. The decryption is performed the exact same way as the encryption (as shown in the code above) except using the decrypt method, obviously. If I try to decrypt a file that was initially downloaded and subsequently uploaded to the server, then it fails at the line where the mac needs to be authenticated (boy did it take me a long time to find that out!).

Any insight you can provide is fantastic. Do you think the problem really lies in application/octet-stream vs application/force-download?

Everything else regarding the encryption method is exactly as it was posted in the cryptastic class function, including no base64 encoding (as shown by my use of the encrypt method above).

Thanks again! I'm going to give the application/octet-stream a shot while I'm waiting to hear back from you.