AES Decrypt not working in iOS 12 or lower

[DanielGZ95]

Describe the bug
I'm trying to decypt data encrypted using AES-256. The decrypt process works fine on devices with iOS 13 and above. Only the devices with iOS 12 are returning invalid data when I call the decrypt method. The string that I'm trying to decrypt is generated inside a web service.
The strange part is that when I encrypt the data inside of my project, the decrypt process works good. Is there a workaround or a solution that I can apply to my project? I need to support iOS 12.

Reproduce
Steps to reproduce:

Xcode: 12.4
CryptoSwift: 1.3.2

let aes = try AES(key: keyString, iv: ivString, padding: .pkcs5)
let data = NSData(base64Encoded: encryptedString, options: NSData.Base64DecodingOptions(rawValue: 0))!
let dec = try aes.decrypt([UInt8](data)) //On iOS12: This returns corrupted data. iOS 13 works fine.
let decryptedData = Data(dec)
                
let final = String(bytes: decryptedData.bytes, encoding: .utf8) 

[krzyzanowskim]

Can you please check these for me:

1. if it happens in Release build on Simulator
2. if it happens in Release build on Device
3. if it happens in Debug build on Device

[krzyzanowskim]

on top of that, can you please test with CryptoSwift 1.3.8?

[DanielGZ95]

I already tested using CryptoSwift 1.3.8 and still not working.
It happens in debug and release builds. I tested with simulator and using phisical device throught browserstack and in all devices the result is the same.

[krzyzanowskim]

Can you please share a sample Xcode project (with values where you see the issue) I could run on my end and see what's going on?

[DanielGZ95]

Sure, this is a sample app. All the methods that I'm using in my real project are in the AppDelegate. In this project I'm getting the same results. I hope you can help me with this please. And thanks!

CryptoSwiftTest.zip

[DanielGZ95]

Hi @krzyzanowskim did you got some time to check my test project?

[imrankst1221]

@DanielGZ95 did you find any solution regarding this?
@krzyzanowskim fetching same issue version '1.4.1' not working on 12.4 (iPad pro 9.7-inch Simulator).

[DanielGZ95]

@imrankst1221 I stop using this library and I used the native way provided by swift. I based my implementation in this resource https://developer.apple.com/documentation/cryptokit/performing_common_cryptographic_operations