/* See LICENSE file for copyright and license details. */
#include "common.h"
#ifdef SUPPORT_MD2


static const unsigned char S[] = {
	0x29, 0x2e, 0x43, 0xc9, 0xa2, 0xd8, 0x7c, 0x01, 0x3d, 0x36, 0x54, 0xa1, 0xec, 0xf0, 0x06, 0x13,
	0x62, 0xa7, 0x05, 0xf3, 0xc0, 0xc7, 0x73, 0x8c, 0x98, 0x93, 0x2b, 0xd9, 0xbc, 0x4c, 0x82, 0xca,
	0x1e, 0x9b, 0x57, 0x3c, 0xfd, 0xd4, 0xe0, 0x16, 0x67, 0x42, 0x6f, 0x18, 0x8a, 0x17, 0xe5, 0x12,
	0xbe, 0x4e, 0xc4, 0xd6, 0xda, 0x9e, 0xde, 0x49, 0xa0, 0xfb, 0xf5, 0x8e, 0xbb, 0x2f, 0xee, 0x7a,
	0xa9, 0x68, 0x79, 0x91, 0x15, 0xb2, 0x07, 0x3f, 0x94, 0xc2, 0x10, 0x89, 0x0b, 0x22, 0x5f, 0x21,
	0x80, 0x7f, 0x5d, 0x9a, 0x5a, 0x90, 0x32, 0x27, 0x35, 0x3e, 0xcc, 0xe7, 0xbf, 0xf7, 0x97, 0x03,
	0xff, 0x19, 0x30, 0xb3, 0x48, 0xa5, 0xb5, 0xd1, 0xd7, 0x5e, 0x92, 0x2a, 0xac, 0x56, 0xaa, 0xc6,
	0x4f, 0xb8, 0x38, 0xd2, 0x96, 0xa4, 0x7d, 0xb6, 0x76, 0xfc, 0x6b, 0xe2, 0x9c, 0x74, 0x04, 0xf1,
	0x45, 0x9d, 0x70, 0x59, 0x64, 0x71, 0x87, 0x20, 0x86, 0x5b, 0xcf, 0x65, 0xe6, 0x2d, 0xa8, 0x02,
	0x1b, 0x60, 0x25, 0xad, 0xae, 0xb0, 0xb9, 0xf6, 0x1c, 0x46, 0x61, 0x69, 0x34, 0x40, 0x7e, 0x0f,
	0x55, 0x47, 0xa3, 0x23, 0xdd, 0x51, 0xaf, 0x3a, 0xc3, 0x5c, 0xf9, 0xce, 0xba, 0xc5, 0xea, 0x26,
	0x2c, 0x53, 0x0d, 0x6e, 0x85, 0x28, 0x84, 0x09, 0xd3, 0xdf, 0xcd, 0xf4, 0x41, 0x81, 0x4d, 0x52,
	0x6a, 0xdc, 0x37, 0xc8, 0x6c, 0xc1, 0xab, 0xfa, 0x24, 0xe1, 0x7b, 0x08, 0x0c, 0xbd, 0xb1, 0x4a,
	0x78, 0x88, 0x95, 0x8b, 0xe3, 0x63, 0xe8, 0x6d, 0xe9, 0xcb, 0xd5, 0xfe, 0x3b, 0x00, 0x1d, 0x39,
	0xf2, 0xef, 0xb7, 0x0e, 0x66, 0x58, 0xd0, 0xe4, 0xa6, 0x77, 0x72, 0xf8, 0xeb, 0x75, 0x4b, 0x0a,
	0x31, 0x44, 0x50, 0xb4, 0x8f, 0xed, 0x1f, 0x1a, 0xdb, 0x99, 0x8d, 0x33, 0x9f, 0x11, 0x83, 0x14};


static void
process_block(const unsigned char *m, unsigned char *c, unsigned char *x)
{
	unsigned i, j, t;

	for (i = 0; i < 16U; i++) {
		x[i] = m[i];
		x[i + 16U] = m[i] ^ c[i];
	}

	t = 0;
	for (i = 0; i < 18U; i++) {
		for (j = 0; j < 16U; j++)
			t = c[j] ^= S[t];
		for (j = 0; j < 32U; j++)
			t = x[j] ^= S[t];
		t = (t + i) & 0xFFU;
	}
}


LIBHASHSUM_1_NONNULL_
static size_t
process(struct libhashsum_hasher *this, const void *data, size_t bytes)
{
	const unsigned char *m = data;
	size_t off = 0;
	unsigned i, t;

	t = this->state.md2.t;
	for (; bytes - off >= 16U; off += 16U) {
		process_block(&m[off], this->state.md2.sum, this->state.md2.x);
		for (i = 0; i < 16U; i++)
			t = this->state.md2.mz[i] ^= S[m[off + i] ^ t];
	}
	this->state.md2.t = t;

	return off;
}


LIBHASHSUM_1_NONNULL_
static int
finalise_common(struct libhashsum_hasher *this, unsigned char *m, size_t bytes, unsigned extra_bits)
{
	unsigned i, t;

	if (extra_bits) {
		errno = EINVAL;
		return -1;
	}

	memset(&m[bytes], 16 - (int)bytes, 16U - bytes);

	t = this->state.md2.t;
	process_block(m, this->state.md2.sum, this->state.md2.x);
	for (i = 0; i < 16U; i++)
		t = this->state.md2.mz[i] ^= S[m[i] ^ t];
	this->state.md2.t = t;

	process_block(this->state.md2.mz, this->state.md2.sum, this->state.md2.x);

	memset(this->state.md2.x, 0, sizeof(this->state.md2.x));
	memset(this->state.md2.mp, 0, sizeof(this->state.md2.mp));
	memset(this->state.md2.mz, 0, sizeof(this->state.md2.mz));
	this->state.md2.t = 0;

	this->hash_output = this->state.md2.sum;
	return 0;
}


LIBHASHSUM_1_NONNULL_
static int
finalise_const(struct libhashsum_hasher *this, const void *data, size_t bytes, unsigned extra_bits)
{
	const unsigned char *m = data;
	size_t r;

	r = process(this, m, bytes);
	m = &m[r];
	bytes -= r;

	memcpy(this->state.md2.mp, m, bytes + (size_t)(extra_bits > 0U));
	return finalise_common(this, this->state.md2.mp, bytes, extra_bits);
}


LIBHASHSUM_1_NONNULL_
static int
finalise(struct libhashsum_hasher *this, void *data, size_t bytes, unsigned extra_bits, size_t size)
{
	unsigned char *m = data;
	size_t r;

	r = process(this, m, bytes);
	m = &m[r];
	bytes -= r;
	size -= r;

	if (size < 16U) {
		memcpy(this->state.md2.mp, m, bytes + (size_t)(extra_bits > 0U));
		m = this->state.md2.mp;
	}
	return finalise_common(this, m, bytes, extra_bits);
}


int
libhashsum_init_md2_hasher(struct libhashsum_hasher *this)
{
	this->algorithm = LIBHASHSUM_MD2;
	this->algorithm_string = "MD2";
	this->input_block_size = 16U;
	this->hash_size = sizeof(this->state.md2.sum);
	this->hash_output = NULL;
	this->supports_non_whole_bytes = 0;
	this->standard_partial_byte_input_encoding = LIBHASHSUM_UNSUPPORTED;
	this->standard_partial_byte_output_encoding = LIBHASHSUM_UNSUPPORTED;
	this->hash_excess_bits = 0;
	this->process = &process;
	this->finalise_const = &finalise_const;
	this->finalise = &finalise;
	this->stretch = NULL;
	this->destroy = NULL;
	memset(&this->state.md2, 0, sizeof(this->state.md2));
	return 0;
}


#else
int
libhashsum_init_md2_hasher(struct libhashsum_hasher *this)
{
	(void) this;
	errno = ENOSYS;
	return -1;
}
#endif