Add an option for disabling encryption for a cache file name

[hasankose]

This option allows disabling md5 encryption for creation cache file name in DiskStorage.

[onevcat]

@hasan-monument Thanks for it.

The change looks good, but may I know what's the use case of it? The cache folder is visible to your users and storing the files with hashed names would protect privacy, that is especially important when you are trying save files with some personal information (like ID or names) in the URLs.

[hasankose]

I was storing images like id.jpg by overriding this func cachePath(forComputedKey key: String) cause of some decision in our team. Now it is deprecated. If I use cache filename with md5 encryption, I need to re-download again with the new update.

My suggestion is you should give an option to developers for that. Kingfisher also has the resource ImageResource(downloadURL: URL, cacheKey: key), If developers want to use md5 encryption, they can pass the encrypted key with cacheKey or they can use different type encryption than md5.

This is just my suggestion, I respect your decision. Thanks for the review.

[onevcat]

Suggested change

	public var useEncryptionForCacheFileName: Bool = true
	public var usesHashedFileName = true

[onevcat]

Suggested change

	/// Default is `true`, means that md5 encryption will be used for creation the cache file name.
	/// Default is `true`, means that the cache file name will be hashed before storing.

[onevcat]

Suggested change

	if self.config.useEncryptionForCacheFileName {
	if self.config.usesHashedFileName {

[onevcat]

@hasan-monument Thanks for the explaination. I understood your case and I agree that we can provide an option for it.

May I ask you to change the name to usesHashedName, since MD5 is not an encryption but just a digest. It will be more accurate to say "hash".

And it would be great if you can also add some tests for this property too. After that, we can merge and release a new version for it.

Thank you!

[hasankose]

I didn't add a test case for validation md5 string, because I didn't want to import the library CommonCrypto to the file. If the test cases aren't enough, I can add it as well.

[onevcat]

Let’s add it. May you can use kf.md5 from this https://github.com/onevcat/Kingfisher/blob/master/Sources/Utility/String%2BMD5.swift to avoid introducing the library importing.

[hasankose]

Thanks for the hint. Added.