-extern bool digest_open_by_name(struct digest *, const char *name, int maclength);
-extern bool digest_open_by_nid(struct digest *, int nid, int maclength);
-extern bool digest_open_sha1(struct digest *, int maclength);
-extern void digest_close(struct digest *);
-extern bool digest_create(struct digest *, const void *indata, size_t inlen, void *outdata);
-extern bool digest_verify(struct digest *, const void *indata, size_t inlen, const void *digestdata);
-extern int digest_get_nid(const struct digest *);
-extern size_t digest_length(const struct digest *);
-extern bool digest_active(const struct digest *);
-