title: Are CC_MD5() and CC_SHA1() available in iOS 4?
body: <p>I am looking to make use of MD5 or SHA-1 in my iOS application targeted at iOS 4 and later. I use the CC_MD5() and CC_SHA1() functions from CommonCrypto/CommonDigest.h. It seems to work fine on an iPhone running iOS 4.1 and in the iPhone 4.0 simulator, but I am concerned because the functions are declared as follows in the iOS 5 SDK that comes with XCode 4.2:</p>
  
  <pre><code>extern unsigned char *CC_MD5(const void *data, CC_LONG len, unsigned char *md)
  __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_5_0);
  
  extern unsigned char *CC_SHA1(const void *data, CC_LONG len, unsigned char *md)
  __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_5_0);
  </code></pre>
  
  <p>This seems to indicate that the functions are only available with iOS 5 and later.</p>
  
  <p>Are these functions allowed in an iOS 4 application, and if so, is there any official reference to document that fact?</p>