/* crypto/kdf/kdf_x9_63.c */
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#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <openssl/kdf.h>

#ifdef CPU_BIGENDIAN
#define cpu_to_be16(v) (v)
#define cpu_to_be32(v) (v)
#else
#define cpu_to_be16(v) ((v << 8) | (v >> 8))
#define cpu_to_be32(v) ((cpu_to_be16(v) << 16) | cpu_to_be16(v >> 16))
#endif

static void *x963_kdf(const EVP_MD *md, const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	EVP_MD_CTX ctx;
	uint32_t counter = 1;
	uint32_t counter_be;
	unsigned char dgst[EVP_MAX_MD_SIZE];
	unsigned int dgstlen;
	unsigned char *pout = out;
	size_t rlen = *outlen;
	size_t len;

	EVP_MD_CTX_init(&ctx);

	while (rlen > 0) {
		counter_be = cpu_to_be32(counter);
		counter++;

		EVP_DigestInit(&ctx, md);
		EVP_DigestUpdate(&ctx, in, inlen);
		EVP_DigestUpdate(&ctx, &counter_be, sizeof(counter_be));
		EVP_DigestFinal(&ctx, dgst, &dgstlen);

		len = dgstlen <= rlen ? dgstlen : rlen;
		memcpy(pout, dgst, len);
		rlen -= len;
		pout += len;
	}

	EVP_MD_CTX_cleanup(&ctx);
	return out;
}

static void *x963_md5kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_md5(), in, inlen, out, outlen);
}

static void *x963_rmd160kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_ripemd160(), in, inlen, out, outlen);
}

static void *x963_sha1kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_sha1(), in, inlen, out, outlen);
}

static void *x963_sha224kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_sha224(), in, inlen, out, outlen);
}

static void *x963_sha256kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_sha256(), in, inlen, out, outlen);
}

static void *x963_sha384kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_sha384(), in, inlen, out, outlen);
}

static void *x963_sha512kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_sha512(), in, inlen, out, outlen);
}

static void *x963_whirlpoolkdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_whirlpool(), in, inlen, out, outlen);
}

static void *x963_sm3kdf(const void *in, size_t inlen,
	void *out, size_t *outlen)
{
	return x963_kdf(EVP_sm3(), in, inlen, out, outlen);
}

KDF_FUNC KDF_get_x9_63(const EVP_MD *md)
{
	if (md == EVP_md5()) {
		return x963_md5kdf;

	} else if (md == EVP_ripemd160()) {
		return x963_rmd160kdf;

	} else if (md == EVP_sha1()) {
		return x963_sha1kdf;

	} else if (md == EVP_sha224()) {
		return x963_sha224kdf;

	} else if (md == EVP_sha256()) {
		return x963_sha256kdf;

	} else if (md == EVP_sha384()) {
		return x963_sha384kdf;

	} else if (md == EVP_sha512()) {
		return x963_sha512kdf;

	} else if (md == EVP_whirlpool()) {
		return x963_whirlpoolkdf;

	} else if (md == EVP_sm3()) {
		return x963_sm3kdf;
	}

	return NULL;
}