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#if !defined( HSS_DERIVE_H_ )
#define HSS_DERIVE_H_
#include "common_defs.h"
/*
* This defines what seed generation logic we use
* Note that changing these parameters will change the mapping
* between private keys.
*
* 0 -> We generate seeds using the process defined in Appendix A of the draft
* 1 -> We use a side channel resistant process, never using any single secret
* seed in more than a defined number of distinct hashes
*/
#define SECRET_METHOD 1
/*
* If we're using the side channel resistant method, this defines the max
* number of times we'll use a single secret. Note that this is the log2
* of the max number of times, and so 3 means 'no more than 8 times'
*/
#define SECRET_MAX 4 /* Never use a seed more than 16 times */
#if SECRET_MAX > 31
#error The code is not designed for a SECRET_MAX that high
#endif
#define SECRET_MAX_MASK (((merkle_index_t)1 << SECRET_MAX) - 1)
struct seed_derive {
const unsigned char *I;
const unsigned char *master_seed;
merkle_index_t q;
unsigned j;
#if SECRET_METHOD == 1
unsigned q_levels, j_levels;
merkle_index_t r_mask;
unsigned j_mask;
#define MAX_Q_HEIGHT ((MAX_MERKLE_HEIGHT + SECRET_MAX - 1) / SECRET_MAX)
#define MAX_J_HEIGHT (( 9 + SECRET_MAX - 1) / SECRET_MAX)
/* '9' is the number of bits a maximum 'p' can take up */
unsigned j_value[MAX_J_HEIGHT]; /* these are the values we insert */
/* into the hash. The lower SECRET_MAX bits are which child of */
/* the parent it is; the higher bits indicate the parents' */
/* identities */
unsigned char q_seed[MAX_Q_HEIGHT][SEED_LEN];
unsigned char j_seed[MAX_Q_HEIGHT][SEED_LEN];
#endif
};
bool hss_seed_derive_init( struct seed_derive *derive,
param_set_t lm, param_set_t ots,
const unsigned char *I, const unsigned char *seed );
/* This sets the internal 'q' value */
/* If we've already have a 'q' value set, it'll try to minimize the number */
/* of hashes done */
/* Once you've done that, you'll need to reset the 'h' */
void hss_seed_derive_set_q( struct seed_derive *derive, merkle_index_t q );
/* This sets the internal 'j' value */
void hss_seed_derive_set_j( struct seed_derive *derive, unsigned j );
#define NUM_ARTIFICIAL_SEEDS 3 /* 3 seeds are listed below */
/* These are the j values used when we're deriving the I/seed values */
/* for child Merkle trees */
#define SEED_CHILD_SEED (~1)
#define SEED_CHILD_I (SEED_CHILD_SEED + 1)
/* This is the j value used when we're asking for the randomizer C */
/* for signing a message */
#define SEED_RANDOMIZER_INDEX (~2)
/* This generates the current seed. If increment_j is set, this will set */
/* up for the next j value */
void hss_seed_derive( unsigned char *seed, struct seed_derive *derive,
bool increment_j );
/* This needs to be called when we done with a seed_derive */
/* That structure contains keying data, this makes sure those are cleaned */
void hss_seed_derive_done( struct seed_derive *derive );
#endif /* HSS_DERIVE_H_ */