iOS CommonCrypto reference [closed]

Question

I'm trying to find some sort of reference for the Apple's CommonCrypto library, because apparently Apple doesn't have any obvious link for that, and the ones given by Google are outdated, like this one below:

https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man3/Common%20Crypto.3cc.html

Any hints on this? Is there a better library I could use to develop an app with lots of cryptographic features?

Thanks.

Answer 1

There is a good sample project called CryptoCompatibility which you can find and download via Xcode. It is better to learn from it than from just looking at the header files. Just search for it in the Documentation & API Reference window.

Answer 2

Most information they provide are in the header file's commence lines. Hold your Command keyboard button and lift click CommonCrypto/CommonCryptor.h to access it.

/*!
@header     CommonCryptor.h
@abstract   Generic interface for symmetric encryption. 

@discussion This interface provides access to a number of symmetric 
            encryption algorithms. Symmetric encryption algorithms come 
            in two "flavors" -  block ciphers, and stream ciphers. Block
            ciphers process data (while both encrypting and decrypting) 
            in discrete chunks of  data called blocks; stream ciphers 
            operate on arbitrary sized data. 

            The object declared in this interface, CCCryptor, provides
            access to both block ciphers and stream ciphers with the same
            API; however some options are available for block ciphers that
            do not apply to stream ciphers. 

            The general operation of a CCCryptor is: initialize it
            with raw key data and other optional fields with
            CCCryptorCreate(); process input data via one or more calls to
            CCCryptorUpdate(), each of which may result in output data
            being written to caller-supplied memory; and obtain possible
            remaining output data with CCCryptorFinal(). The CCCryptor is
            disposed of via CCCryptorRelease(), or it can be reused (with
            the same key data as provided to CCCryptorCreate()) by calling
            CCCryptorReset(). 

            CCCryptors can be dynamically allocated by this module, or 
            their memory can be allocated by the caller. See discussion for
            CCCryptorCreate() and CCCryptorCreateFromData() for information 
            on CCCryptor allocation.

            One option for block ciphers is padding, as defined in PKCS7;
            when padding is enabled, the total amount of data encrypted
            does not have to be an even multiple of the block size, and 
            the actual length of plaintext is calculated during decryption. 

            Another option for block ciphers is Cipher Block Chaining, known
            as CBC mode. When using CBC mode, an Initialization Vector (IV)
            is provided along with the key when starting an encrypt
            or decrypt operation. If CBC mode is selected and no IV is 
            provided, an IV of all zeroes will be used. 

            CCCryptor also implements block bufferring, so that individual
            calls to CCCryptorUpdate() do not have to provide data whose
            length is aligned to the block size. (If padding is disabled,
            encrypting with block ciphers does require that the *total*
            length of data input to CCCryptorUpdate() call(s) be aligned
            to the block size.)

            A given CCCryptor can only be used by one thread at a time;
            multiple threads can use safely different CCCryptors at the
            same time.              
*/