diff --git a/src/common/crypto.c b/src/common/crypto.c
index aeef1e3c6b..b9829ecd1a 100644
--- a/src/common/crypto.c
+++ b/src/common/crypto.c
@@ -1635,7 +1635,8 @@ crypto_digest_assign(crypto_digest_t *into,
 /** Given a list of strings in <b>lst</b>, set the <b>len_out</b>-byte digest
  * at <b>digest_out</b> to the hash of the concatenation of those strings,
  * plus the optional string <b>append</b>, computed with the algorithm
- * <b>alg</b>. */
+ * <b>alg</b>.
+ * <b>out_len</b> must be \<= DIGEST256_LEN. */
 void
 crypto_digest_smartlist(char *digest_out, size_t len_out,
                         const smartlist_t *lst, const char *append,
diff --git a/src/or/routerparse.c b/src/or/routerparse.c
index 63f8fab104..87dc608e57 100644
--- a/src/or/routerparse.c
+++ b/src/or/routerparse.c
@@ -683,7 +683,12 @@ router_get_extrainfo_hash(const char *s, size_t s_len, char *digest)
                               "\nrouter-signature",'\n', DIGEST_SHA1);
 }
 
-/** DOCDOC */
+/** Helper: used to generate signatures for routers, directories and
+ * network-status objects.  Given a <b>digest_len</b>-byte digest in
+ * <b>digest</b> and a secret <b>private_key</b>, generate an PKCS1-padded
+ * signature, BASE64-encode it, surround it with -----BEGIN/END----- pairs,
+ * and return the new signature on success or NULL on failure.
+ */
 char *
 router_get_dirobj_signature(const char *digest,
                             size_t digest_len,