#include "config.h"
#include <stdio.h>
#include <string.h>

/**
 * crypto/shachain - compactly-representable chain of 256-bit numbers.
 *
 * This code produces a practically infinite (2^64) chain of 256-bit numbers
 * from a single number, such that you can't derive element N from any element
 * less than N, but can efficiently derive element N from a limited number
 * of elements >= N.
 *
 * License: BSD-MIT
 * Author: Rusty Russell <rusty@rustcorp.com.au>
 *
 * Example:
 *
 * #include <ccan/crypto/shachain/shachain.h>
 * #include <ccan/err/err.h>
 * #include <stdio.h>
 * #include <stdlib.h>
 * #include <string.h>
 *
 * int main(int argc, char *argv[])
 * {
 *	size_t i, j, limit = 10;
 *	struct sha256 seed;
 *
 *	if (argc < 2)
 *		errx(1, "Usage: %s <passphrase> [<num-to-generate>]", argv[0]);
 *	sha256(&seed, argv[1], strlen(argv[1]));
 *	if (argv[2])
 *		limit = atol(argv[2]);
 *
 *	for (i = 0; i < limit; i++) {
 *		struct sha256 v;
 *		shachain_from_seed(&seed, i, &v);
 *		printf("%zu: ", i);
 *		for (j = 0; j < sizeof(v.u.u8); j++)
 *			printf("%02x", v.u.u8[j]);
 *		printf("\n");
 *	}
 *	return 0;
 * }
 */
int main(int argc, char *argv[])
{
	/* Expect exactly one argument */
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		printf("ccan/ilog\n");
		printf("ccan/crypto/sha256\n");
		return 0;
	}

	return 1;
}