#ifndef XMSS_COMMONS_H
#define XMSS_COMMONS_H

#include <stdint.h>
#include "params.h"

/**
 * Converts the value of 'in' to 'len' bytes in big-endian byte order.
 */
void ull_to_bytes(unsigned char *out, unsigned int outlen,
                  unsigned long long in);

/**
 * Converts the inlen bytes in 'in' from big-endian byte order to an integer.
 */
unsigned long long bytes_to_ull(const unsigned char *in, unsigned int inlen);

/**
 * Computes the leaf at a given address. First generates the WOTS key pair,
 * then computes leaf using l_tree. As this happens position independent, we
 * only require that addr encodes the right ltree-address.
 */
void gen_leaf_wots(const xmss_params *params, unsigned char *leaf,
                   const unsigned char *sk_seed, const unsigned char *pub_seed,
                   uint32_t ltree_addr[8], uint32_t ots_addr[8]);

/**
 * Used for pseudo-random key generation.
 * Generates the seed for the WOTS key pair at address 'addr'.
 *
 * Takes n-byte sk_seed and returns n-byte seed using 32 byte address 'addr'.
 */
void get_seed(const xmss_params *params, unsigned char *seed,
              const unsigned char *sk_seed, uint32_t addr[8]);

/**
 * Computes a leaf node from a WOTS public key using an L-tree.
 * Note that the WOTS public key is destroyed.
 */
void l_tree(const xmss_params *params,
            unsigned char *leaf, unsigned char *wots_pk,
            const unsigned char *pub_seed, uint32_t addr[8]);

/**
 * Computes the randomized message hash.
 */
void hash_message(const xmss_params *params, unsigned char *mhash,
                  const unsigned char *R, const unsigned char *root,
                  unsigned long long idx,
                  const unsigned char *m, unsigned long long mlen);

/**
 * Verifies a given message signature pair under a given public key.
 * Note that this assumes a pk without an OID, i.e. [root || PUB_SEED]
 */
int xmss_core_sign_open(const xmss_params *params,
                        unsigned char *m, unsigned long long *mlen,
                        const unsigned char *sm, unsigned long long smlen,
                        const unsigned char *pk);

/**
 * Verifies a given message signature pair under a given public key.
 * Note that this assumes a pk without an OID, i.e. [root || PUB_SEED]
 */
int xmssmt_core_sign_open(const xmss_params *params,
                          unsigned char *m, unsigned long long *mlen,
                          const unsigned char *sm, unsigned long long smlen,
                          const unsigned char *pk);
#endif