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Provide internal ARC4 implementation
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Now you can build bittorrent support without without external
libraries, meaning you can skip libnettle, libgmp, libgcrypt, GnuTLS and
OpenSSL on OSX (for now).
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nmaier committed Sep 24, 2013
1 parent e854463 commit 99f170b
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Showing 6 changed files with 149 additions and 25 deletions.
7 changes: 4 additions & 3 deletions configure.ac
Original file line number Diff line number Diff line change
Expand Up @@ -518,12 +518,13 @@ fi
if test "x$have_libnettle" = "xyes" ||
test "x$have_libgcrypt" = "xyes" ||
test "x$have_openssl" = "xyes"; then
have_rc4=yes
AM_CONDITIONAL([USE_INTERNAL_ARC4], false)
else
AC_DEFINE([USE_INTERNAL_ARC4], [1], [Define to 1 if internal ARC4 support is enabled.])
AM_CONDITIONAL([USE_INTERNAL_ARC4], true)
fi


if test "x$enable_bittorrent" = "xyes" &&
test "x$have_rc4" = "xyes" &&
test "x$enable_message_digest" = "xyes"; then
AC_DEFINE([ENABLE_BITTORRENT], [1],
[Define to 1 if BitTorrent support is enabled.])
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24 changes: 4 additions & 20 deletions src/ARC4Encryptor.h
Original file line number Diff line number Diff line change
Expand Up @@ -36,31 +36,15 @@
#define D_ARC4_ENCRYPTOR_H

#include "common.h"
#ifdef HAVE_LIBNETTLE

#ifdef USE_INTERNAL_ARC4
# include "InternalARC4Encryptor.h"
#elif HAVE_LIBNETTLE
# include "LibnettleARC4Encryptor.h"
#elif HAVE_LIBGCRYPT
# include "LibgcryptARC4Encryptor.h"
#elif HAVE_OPENSSL
# include "LibsslARC4Encryptor.h"
#else

// provide empty implementation to compile sources without both libgcrypt and
// openssl installed
namespace aria2 {

class ARC4Encryptor {
public:
ARC4Encryptor() {}

~ARC4Encryptor() {}

void init(const unsigned char* key, size_t keyLength) {}

void encrypt(size_t len, unsigned char* out, const unsigned char* in);
};

} // namespace aria2

#endif

#endif // D_ARC4_ENCRYPTOR_H
73 changes: 73 additions & 0 deletions src/InternalARC4Encryptor.cc
Original file line number Diff line number Diff line change
@@ -0,0 +1,73 @@
/* <!-- copyright */
/*
* aria2 - The high speed download utility
*
* Copyright (C) 2013 Nils Maier
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations
* including the two.
* You must obey the GNU General Public License in all respects
* for all of the code used other than OpenSSL. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you
* do not wish to do so, delete this exception statement from your
* version. If you delete this exception statement from all source
* files in the program, then also delete it here.
*/
/* copyright --> */

#include "InternalARC4Encryptor.h"

namespace aria2 {

ARC4Encryptor::~ARC4Encryptor()
{
for (auto& c : state_) c = 0;
i = j = 0;
}
void ARC4Encryptor::init(const unsigned char* key, size_t keyLength)
{
j = 0;
for (auto& c : state_) c = j++;

j = 0;
for (i = 0; i < sizeof(state_); ++i) {
j = (j + state_[i] + key[i % keyLength]) & 0xff;
auto tmp = state_[i];
state_[i] = state_[j];
state_[j] = tmp;
}
i = j = 0;
}

void ARC4Encryptor::encrypt(size_t len, unsigned char* out,
const unsigned char* in)
{
for (auto c = 0; c < len; ++c) {
i = (i + 1) & 0xff;
j = (j + state_[i]) & 0xff;
auto sj = state_[i];
auto si = state_[i] = state_[j];
state_[j] = sj;
out[c] = in[c] ^ state_[(si + sj) & 0xff];
}
}

} // namespace aria2
60 changes: 60 additions & 0 deletions src/InternalARC4Encryptor.h
Original file line number Diff line number Diff line change
@@ -0,0 +1,60 @@
/* <!-- copyright */
/*
* aria2 - The high speed download utility
*
* Copyright (C) 2013 Nils Maier
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* In addition, as a special exception, the copyright holders give
* permission to link the code of portions of this program with the
* OpenSSL library under certain conditions as described in each
* individual source file, and distribute linked combinations
* including the two.
* You must obey the GNU General Public License in all respects
* for all of the code used other than OpenSSL. If you modify
* file(s) with this exception, you may extend this exception to your
* version of the file(s), but you are not obligated to do so. If you
* do not wish to do so, delete this exception statement from your
* version. If you delete this exception statement from all source
* files in the program, then also delete it here.
*/
/* copyright --> */
#ifndef D_INTERNAL_ARC4_ENCRYPTOR_H
#define D_INTERNAL_ARC4_ENCRYPTOR_H

#include "common.h"

namespace aria2 {

class ARC4Encryptor {
private:
unsigned char state_[256];
unsigned i, j;

public:
ARC4Encryptor() {}
~ARC4Encryptor();

void init(const unsigned char* key, size_t keyLength);

// Encrypts data in in buffer to out buffer. in and out can be the
// same buffer.
void encrypt(size_t len, unsigned char* out, const unsigned char* in);
};

} // namespace aria2

#endif // D_INTERNAL_ARC4_ENCRYPTOR_H
4 changes: 4 additions & 0 deletions src/Makefile.am
Original file line number Diff line number Diff line change
Expand Up @@ -337,6 +337,10 @@ if USE_INTERNAL_BIGNUM
SRCS += InternalDHKeyExchange.cc InternalDHKeyExchange.h bignum.h
endif

if USE_INTERNAL_ARC4
SRCS += InternalARC4Encryptor.cc InternalARC4Encryptor.h
endif

if USE_INTERNAL_MD
SRCS += InternalMessageDigestImpl.cc sha1.c md5.c
endif # USE_WINDOWS_MD
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6 changes: 4 additions & 2 deletions test/ARC4Test.cc
Original file line number Diff line number Diff line change
Expand Up @@ -37,14 +37,16 @@ void ARC4Test::testEncrypt()

unsigned char encrypted[LEN];
unsigned char decrypted[LEN];

enc.encrypt(LEN, encrypted, key);
CPPUNIT_ASSERT(memcmp(key, encrypted, LEN) != 0);
dec.encrypt(LEN, decrypted, encrypted);

CPPUNIT_ASSERT(memcmp(key, decrypted, LEN) == 0);

// once more
enc.encrypt(LEN, encrypted, key);
CPPUNIT_ASSERT(memcmp(key, encrypted, LEN) != 0);
dec.encrypt(LEN, decrypted, encrypted);

CPPUNIT_ASSERT(memcmp(key, decrypted, LEN) == 0);
}

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