+/**
+ * get_fingerprint - Given a public key returns the fingerprint.
+ * @publickey: The key to calculate the id for.
+ * @fingerprint: The fingerprint (must be at least 20 bytes of space).
+ * @len: The length of the returned fingerprint.
+ *
+ * This function returns the fingerprint for a given public key. As Type 3
+ * fingerprints are 16 bytes and Type 4 are 20 the len field indicates
+ * which we've returned.
+ */
+unsigned char *get_fingerprint(struct openpgp_packet *packet,
+ unsigned char *fingerprint,
+ size_t *len);
+