Both Security Framework and Common Crypto rely on the corecrypto library to provide implementations of low level cryptographic primitives. This is also the library submitted for validation of compliance with U.S. Federal Information Processing Standards (FIPS) 140-2 Level 1. Although corecrypto does not directly provide programming interfaces for developers and should not be used by iOS or OS X apps, the source code is available to allow for verification of its security characteristics and correct functioning.