Start nacl.ffi.libsodium with the low level hashing functions

nacl/ffi/libsodium.py

+"""
+CFFI interface to libsodium the library
+"""
+from cffi import FFI
+
+ffi = FFI()
+
+ffi.cdef(
+    # Low Level Hashing functions
+    """
+        static const int crypto_hash_BYTES;
+        static const int crypto_hash_sha256_BYTES;
+        static const int crypto_hash_sha512_BYTES;
+
+        int crypto_hash(unsigned char *out, const unsigned char *in, unsigned long long inlen);
+        int crypto_hash_sha256(unsigned char *out, const unsigned char *in, unsigned long long inlen);
+        int crypto_hash_sha512(unsigned char *out, const unsigned char *in, unsigned long long inlen);
+    """
+)
+
+lib = ffi.verify("#include <sodium.h>", libraries=["sodium"])