+const struct ccmode_siv *ccaes_siv_encrypt_mode(void);
+const struct ccmode_siv *ccaes_siv_decrypt_mode(void);
+
+const struct ccmode_siv_hmac *ccaes_siv_hmac_sha256_encrypt_mode(void);
+const struct ccmode_siv_hmac *ccaes_siv_hmac_sha256_decrypt_mode(void);
+
+/*!
+ @function ccaes_unwind
+ @abstract "Unwind" an AES encryption key to the equivalent decryption key.
+
+ @param key_nbytes Length in bytes of both the input and output keys
+ @param key The input AES encryption key
+ @param out The output AES decryption key
+
+ @result @p CCERR_OK iff successful.
+ @discussion Only AES256 (i.e. 32-byte) keys are supported. This function is not necessary in typical AES usage; consult the maintainers before using it.
+*/
+int ccaes_unwind(size_t key_nbytes, const void *key, void *out);
+