/* radare - LGPL - Copyright 2017-2025 - pancake */

#include <r_muta.h>
#include "algo/serpent.h"

static bool serpent_set_key(RMutaSession *ms, const ut8 *key, int keylen, int mode, int direction) {
	free (ms->data);
	ms->data = R_NEW0 (struct serpent_state);
	struct serpent_state *st = ms->data;
	if (!st) {
		return false;
	}
	R_LOG_INFO ("key_length: %d", keylen);
	if ((keylen != 128 / 8) && (keylen != 192 / 8) && (keylen != 256 / 8)) {
		return false;
	}
	st->key_size = keylen * 8;
	R_LOG_INFO ("key_size: %d", st->key_size);
	memcpy (st->key, key, keylen);
	ms->dir = direction;
	return true;
}

static int serpent_get_key_size(RMutaSession *ms) {
	struct serpent_state *st = ms->data;
	return st? st->key_size: 0;
}

#define BLOCK_SIZE 16

static bool update(RMutaSession *ms, const ut8 *buf, int len) {
	// Pad to the block size, do not append dummy block
	const int diff = (BLOCK_SIZE - (len % BLOCK_SIZE)) % BLOCK_SIZE;
	const int size = len + diff;
	const int blocks = size / BLOCK_SIZE;
	int i, j;

	ut8 *const obuf = calloc (4, size / 4);
	if (!obuf) {
		return false;
	}
	ut32 *const ibuf = calloc (4, size / 4);
	if (!ibuf) {
		free (obuf);
		return false;
	}
	ut32 *const tmp = calloc (4, size / 4);
	if (!tmp) {
		free (obuf);
		free (ibuf);
		return false;
	}

	// Construct ut32 blocks from byte stream
	for (j = 0; j < len / 4; j++) {
		ibuf[j] = r_read_le32 (buf + 4 * j);
	}
	if (len & 0x3) {
		ut8 tail[4] = { 0 }; // Zero padding
		memcpy (tail, buf + (len & ~0x3), len & 0x3);
		ibuf[len / 4] = r_read_le32 (tail);
	}

	struct serpent_state *st = ms->data;
	if (!st) {
		R_LOG_ERROR ("No state");
		free (obuf);
		free (ibuf);
		free (tmp);
		return false;
	}
	switch (ms->dir) {
	case R_MUTA_OP_ENCRYPT:
		for (i = 0; i < blocks; i++) {
			// delta in number of ut32
			const int delta = (BLOCK_SIZE * i) / 4;
			serpent_encrypt (st, ibuf + delta, tmp + delta);
		}
		break;
	case R_MUTA_OP_DECRYPT:
		for (i = 0; i < blocks; i++) {
			// delta in number of ut32
			const int delta = (BLOCK_SIZE * i) / 4;
			serpent_decrypt (st, ibuf + delta, tmp + delta);
		}
		break;
	}

	// Construct ut32 blocks from byte stream
	int k;
	for (j = 0; j < size / 4; j++) {
		k = 4 * j;
		obuf[k] = tmp[j] & 0xff;
		obuf[k + 1] = (tmp[j] >> 8) & 0xff;
		obuf[k + 2] = (tmp[j] >> 16) & 0xff;
		obuf[k + 3] = (tmp[j] >> 24) & 0xff;
	}

	r_muta_session_append (ms, obuf, size);
	free (obuf);
	free (ibuf);
	free (tmp);
	return true;
}

static bool end(RMutaSession *ms, const ut8 *buf, int len) {
	return update (ms, buf, len);
}

RMutaPlugin r_muta_plugin_serpent = {
	.type = R_MUTA_TYPE_CRYPTO,
	.implements = "serpent",
	.meta = {
		.name = "serpent-ecb",
		.desc = "Serpent block cipher with Electronic Code Book mode",
		.license = "LGPL-3.0-only",
		.author = "pancake",
	},
	.set_key = serpent_set_key,
	.get_key_size = serpent_get_key_size,
	.update = update,
	.end = end
};

#ifndef R2_PLUGIN_INCORE
R_API RLibStruct radare_plugin = {
	.type = R_LIB_TYPE_CRYPTO,
	.data = &r_muta_plugin_serpent,
	.version = R2_VERSION
};
#endif