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262 lines
7.1 KiB
C
262 lines
7.1 KiB
C
/* arctwo.c
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The cipher described in rfc2268; aka Ron's Cipher 2.
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Copyright (C) 2004 Simon Josefsson
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Copyright (C) 2003 Nikos Mavroyanopoulos
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Copyright (C) 2004 Free Software Foundation, Inc.
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Copyright (C) 2004, 2014 Niels Möller
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This file is part of GNU Nettle.
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GNU Nettle is free software: you can redistribute it and/or
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modify it under the terms of either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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or both in parallel, as here.
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GNU Nettle is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see http://www.gnu.org/licenses/.
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*/
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/* This implementation was written by Nikos Mavroyanopoulos for GNUTLS
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* as a Libgcrypt module (gnutls/lib/x509/rc2.c) and later adapted for
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* direct use by Libgcrypt by Werner Koch and later adapted for direct
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* use by Nettle by Simon Josefsson and Niels Möller.
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*
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* The implementation here is based on Peter Gutmann's RRC.2 paper and
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* RFC 2268.
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*/
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#if HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <assert.h>
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#include "arctwo.h"
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#include "macros.h"
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static const uint8_t arctwo_sbox[] = {
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0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed,
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0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d,
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0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e,
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0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2,
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0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13,
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0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
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0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b,
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0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82,
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0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c,
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0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc,
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0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1,
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0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
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0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57,
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0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03,
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0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7,
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0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7,
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0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7,
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0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
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0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74,
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0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec,
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0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc,
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0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39,
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0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a,
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0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
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0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae,
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0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9,
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0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c,
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0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9,
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0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0,
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0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
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0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77,
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0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad
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};
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#define rotl16(x,n) (((x) << ((uint16_t)(n))) | ((x) >> (16 - (uint16_t)(n))))
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#define rotr16(x,n) (((x) >> ((uint16_t)(n))) | ((x) << (16 - (uint16_t)(n))))
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void
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arctwo_encrypt (struct arctwo_ctx *ctx,
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size_t length, uint8_t *dst, const uint8_t *src)
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{
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FOR_BLOCKS (length, dst, src, ARCTWO_BLOCK_SIZE)
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{
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register unsigned i;
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uint16_t w0, w1, w2, w3;
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w0 = LE_READ_UINT16 (&src[0]);
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w1 = LE_READ_UINT16 (&src[2]);
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w2 = LE_READ_UINT16 (&src[4]);
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w3 = LE_READ_UINT16 (&src[6]);
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for (i = 0; i < 16; i++)
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{
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register unsigned j = i * 4;
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/* For some reason I cannot combine those steps. */
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w0 += (w1 & ~w3) + (w2 & w3) + ctx->S[j];
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w0 = rotl16 (w0, 1);
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w1 += (w2 & ~w0) + (w3 & w0) + ctx->S[j + 1];
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w1 = rotl16 (w1, 2);
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w2 += (w3 & ~w1) + (w0 & w1) + ctx->S[j + 2];
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w2 = rotl16 (w2, 3);
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w3 += (w0 & ~w2) + (w1 & w2) + ctx->S[j + 3];
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w3 = rotl16 (w3, 5);
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if (i == 4 || i == 10)
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{
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w0 += ctx->S[w3 & 63];
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w1 += ctx->S[w0 & 63];
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w2 += ctx->S[w1 & 63];
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w3 += ctx->S[w2 & 63];
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}
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}
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LE_WRITE_UINT16 (&dst[0], w0);
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LE_WRITE_UINT16 (&dst[2], w1);
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LE_WRITE_UINT16 (&dst[4], w2);
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LE_WRITE_UINT16 (&dst[6], w3);
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}
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}
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void
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arctwo_decrypt (struct arctwo_ctx *ctx,
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size_t length, uint8_t *dst, const uint8_t *src)
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{
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FOR_BLOCKS (length, dst, src, ARCTWO_BLOCK_SIZE)
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{
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register unsigned i;
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uint16_t w0, w1, w2, w3;
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w0 = LE_READ_UINT16 (&src[0]);
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w1 = LE_READ_UINT16 (&src[2]);
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w2 = LE_READ_UINT16 (&src[4]);
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w3 = LE_READ_UINT16 (&src[6]);
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for (i = 16; i-- > 0; )
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{
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register unsigned j = i * 4;
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w3 = rotr16 (w3, 5);
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w3 -= (w0 & ~w2) + (w1 & w2) + ctx->S[j + 3];
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w2 = rotr16 (w2, 3);
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w2 -= (w3 & ~w1) + (w0 & w1) + ctx->S[j + 2];
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w1 = rotr16 (w1, 2);
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w1 -= (w2 & ~w0) + (w3 & w0) + ctx->S[j + 1];
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w0 = rotr16 (w0, 1);
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w0 -= (w1 & ~w3) + (w2 & w3) + ctx->S[j];
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if (i == 5 || i == 11)
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{
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w3 = w3 - ctx->S[w2 & 63];
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w2 = w2 - ctx->S[w1 & 63];
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w1 = w1 - ctx->S[w0 & 63];
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w0 = w0 - ctx->S[w3 & 63];
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}
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}
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LE_WRITE_UINT16 (&dst[0], w0);
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LE_WRITE_UINT16 (&dst[2], w1);
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LE_WRITE_UINT16 (&dst[4], w2);
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LE_WRITE_UINT16 (&dst[6], w3);
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}
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}
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void
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arctwo_set_key_ekb (struct arctwo_ctx *ctx,
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size_t length, const uint8_t *key, unsigned ekb)
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{
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size_t i;
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/* Expanded key, treated as octets */
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uint8_t S[128];
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uint8_t x;
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assert (length >= ARCTWO_MIN_KEY_SIZE);
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assert (length <= ARCTWO_MAX_KEY_SIZE);
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assert (ekb <= 1024);
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for (i = 0; i < length; i++)
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S[i] = key[i];
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/* Phase 1: Expand input key to 128 bytes */
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for (i = length; i < ARCTWO_MAX_KEY_SIZE; i++)
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S[i] = arctwo_sbox[(S[i - length] + S[i - 1]) & 255];
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S[0] = arctwo_sbox[S[0]];
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/* Reduce effective key size to ekb bits, if requested by caller. */
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if (ekb > 0 && ekb < 1024)
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{
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int len = (ekb + 7) >> 3;
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i = 128 - len;
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x = arctwo_sbox[S[i] & (255 >> (7 & -ekb))];
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S[i] = x;
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while (i--)
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{
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x = arctwo_sbox[x ^ S[i + len]];
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S[i] = x;
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}
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}
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/* Make the expanded key endian independent. */
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for (i = 0; i < 64; i++)
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ctx->S[i] = LE_READ_UINT16(S + i * 2);
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}
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void
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arctwo_set_key (struct arctwo_ctx *ctx, size_t length, const uint8_t *key)
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{
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arctwo_set_key_ekb (ctx, length, key, 8 * length);
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}
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void
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arctwo_set_key_gutmann (struct arctwo_ctx *ctx,
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size_t length, const uint8_t *key)
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{
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arctwo_set_key_ekb (ctx, length, key, 0);
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}
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void
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arctwo40_set_key (struct arctwo_ctx *ctx, const uint8_t *key)
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{
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arctwo_set_key_ekb (ctx, 5, key, 40);
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}
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void
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arctwo64_set_key (struct arctwo_ctx *ctx, const uint8_t *key)
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{
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arctwo_set_key_ekb (ctx, 8, key, 64);
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}
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void
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arctwo128_set_key (struct arctwo_ctx *ctx, const uint8_t *key)
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{
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arctwo_set_key_ekb (ctx, 16, key, 128);
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}
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void
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arctwo128_set_key_gutmann (struct arctwo_ctx *ctx,
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const uint8_t *key)
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{
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arctwo_set_key_ekb (ctx, 16, key, 1024);
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}
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