diff -r bf3695fee719 -r 481802342fdf libidav/crypto.h
--- a/libidav/crypto.h	Mon Feb 04 14:11:57 2019 +0100
+++ b/libidav/crypto.h	Mon Feb 04 17:17:48 2019 +0100
@@ -109,8 +109,8 @@
 void aes_encrypter_close(AESEncrypter *enc);
 int aes_encrypter_reset(AESEncrypter  *enc, curl_off_t offset, int origin);
 
-char* aes_encrypt(char *in, size_t len, DavKey *key);
-char* aes_decrypt(char *in, size_t *len, DavKey *key);
+char* aes_encrypt(const char *in, size_t len, DavKey *key);
+char* aes_decrypt(const char *in, size_t *len, DavKey *key);
 
 void dav_get_hash(DAV_SHA_CTX *sha256, unsigned char *buf);