Count SHA1 of NSData

I need to count SHA1 checksum of NSData object. How c开发者_如何学编程an I do it?

Thanks in advance!

---

There is a SHA1 function in the openssl lib (link with -lcrypto linker option):

#include <openssl/sha.h>

NSMutableData *hashData = [NSMutableData dataWithLength:SHA_DIGEST_LENGTH];
SHA1([input bytes], [input length], [hashData mutableBytes]);