AES/CFB8 cipher on iOS

Question

I am trying to implement an AES/CFB8 streaming cipher on iOS. I believe that the way to accomplish this is to use the CommonCrypto library provided by Apple.

All of the little documentation I have found only shows block ciphers, so how would one use the library to accomplish an AES/CFB8 stream cipher?

score 0 · Answer 1 · edited Aug 29 '12 at 23:48

0

First of all, you can take a look at the code to encrypt/decrypt here: http://robnapier.net/blog/aes-commoncrypto-564

Secondly, I believe that iOS CommonCrypto uses CBC by default and the only other option is to use kCCOptionECBMode flag to get ECB.

If you are fine with CBC, you can use CommonCrypto. If you need specifically CFB than you may need to integrate some 3rd party encryption library.

edited Aug 29 '12 at 23:48

CodesInChaos

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answered Aug 29 '12 at 21:49

Victor Ronin

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Thanks for the answer, but, sadly, I have to follow a spec (not my own) calling for CFB8. – magmastonealex Aug 30 '12 at 22:09
BTW. You can build CFB on your own based on ECB. Look here: http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher_feedback_.28CFB.29 – Victor Ronin Aug 31 '12 at 03:21

AES/CFB8 cipher on iOS

1 Answers1