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keepassx1/src/crypto/twofish.cpp

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/*
* Fast, portable, and easy-to-use Twofish implementation,
* Version 0.3.
* Copyright (c) 2002 by Niels Ferguson.
* (See further down for the almost-unrestricted licensing terms.)
*
* --------------------------------------------------------------------------
* There are two files for this implementation:
* - twofish.h, the header file.
* - twofish.c, the code file.
*
* To incorporate this code into your program you should:
* - Check the licensing terms further down in this comment.
* - Fix the two type definitions in twofish.h to suit your platform.
* - Fix a few definitions in twofish.c in the section marked
* PLATFORM FIXES. There is one important ones that affects
* functionality, and then a few definitions that you can optimise
* for efficiency but those have no effect on the functionality.
* Don't change anything else.
* - Put the code in your project and compile it.
*
* To use this library you should:
* - Call Twofish_initialise() in your program before any other function in
* this library.
* - Use Twofish_prepare_key(...) to convert a key to internal form.
* - Use Twofish_encrypt(...) and Twofish_decrypt(...) to encrypt and decrypt
* data.
* See the comments in the header file for details on these functions.
* --------------------------------------------------------------------------
*
* There are many Twofish implementation available for free on the web.
* Most of them are hard to integrate into your own program.
* As we like people to use our cipher, I thought I would make it easier.
* Here is a free and easy-to-integrate Twofish implementation in C.
* The latest version is always available from my personal home page at
* http://niels.ferguson.net/
*
* Integrating library code into a project is difficult because the library
* header files interfere with the project's header files and code.
* And of course the project's header files interfere with the library code.
* I've tried to resolve these problems here.
* The header file of this implementation is very light-weight.
* It contains two typedefs, a structure, and a few function declarations.
* All names it defines start with "Twofish_".
* The header file is therefore unlikely to cause problems in your project.
* The code file of this implementation doesn't need to include the header
* files of the project. There is thus no danger of the project interfering
* with all the definitions and macros of the Twofish code.
* In most situations, all you need to do is fill in a few platform-specific
* definitions in the header file and code file,
* and you should be able to run the Twofish code in your project.
* I estimate it should take you less than an hour to integrate this code
* into your project, most of it spent reading the comments telling you what
* to do.
*
* For people using C++: it is very easy to wrap this library into a
* TwofishKey class. One of the big advantages is that you can automate the
* wiping of the key material in the destructor. I have not provided a C++
* class because the interface depends too much on the abstract base class
* you use for block ciphers in your program, which I don't know about.
*
* This implementation is designed for use on PC-class machines. It uses the
* Twofish 'full' keying option which uses large tables. Total table size is
* around 5-6 kB for static tables plus 4.5 kB for each pre-processed key.
* If you need an implementation that uses less memory,
* take a look at Brian Gladman's code on his web site:
* http://fp.gladman.plus.com/cryptography_technology/aes/
* He has code for all AES candidates.
* His Twofish code has lots of options trading off table size vs. speed.
* You can also take a look at the optimised code by Doug Whiting on the
* Twofish web site
* http://www.counterpane.com/twofish.html
* which has loads of options.
* I believe these existing implementations are harder to re-use because they
* are not clean libraries and they impose requirements on the environment.
* This implementation is very careful to minimise those,
* and should be easier to integrate into any larger program.
*
* The default mode of this implementation is fully portable as it uses no
* behaviour not defined in the C standard. (This is harder than you think.)
* If you have any problems porting the default mode, please let me know
* so that I can fix the problem. (But only if this code is at fault, I
* don't fix compilers.)
* Most of the platform fixes are related to non-portable but faster ways
* of implementing certain functions.
*
* In general I've tried to make the code as fast as possible, at the expense
* of memory and code size. However, C does impose limits, and this
* implementation will be slower than an optimised assembler implementation.
* But beware of assembler implementations: a good Pentium implementation
* uses completely different code than a good Pentium II implementation.
* You basically have to re-write the assembly code for every generation of
* processor. Unless you are severely pressed for speed, stick with C.
*
* The initialisation routine of this implementation contains a self-test.
* If initialisation succeeds without calling the fatal routine, then
* the implementation works. I don't think you can break the implementation
* in such a way that it still passes the tests, unless you are malicious.
* In other words: if the initialisation routine returns,
* you have successfully ported the implementation.
* (Or not implemented the fatal routine properly, but that is your problem.)
*
* I'm indebted to many people who helped me in one way or another to write
* this code. During the design of Twofish and the AES process I had very
* extensive discussions of all implementation issues with various people.
* Doug Whiting in particular provided a wealth of information. The Twofish
* team spent untold hours discussion various cipher features, and their
* implementation. Brian Gladman implemented all AES candidates in C,
* and we had some fruitful discussions on how to implement Twofish in C.
* Jan Nieuwenhuizen tested this code on Linux using GCC.
*
* Now for the license:
* The author hereby grants a perpetual license to everybody to
* use this code for any purpose as long as the copyright message is included
* in the source code of this or any derived work.
*
* Yes, this means that you, your company, your club, and anyone else
* can use this code anywhere you want. You can change it and distribute it
* under the GPL, include it in your commercial product without releasing
* the source code, put it on the web, etc.
* The only thing you cannot do is remove my copyright message,
* or distribute any source code based on this implementation that does not
* include my copyright message.
*
* I appreciate a mention in the documentation or credits,
* but I understand if that is difficult to do.
* I also appreciate it if you tell me where and why you used my code.
*
* Please send any questions or comments to niels@ferguson.net
*
* Have Fun!
*
* Niels
*/
/*
* DISCLAIMER: As I'm giving away my work for free, I'm of course not going
* to accept any liability of any form. This code, or the Twofish cipher,
* might very well be flawed; you have been warned.
* This software is provided as-is, without any kind of warrenty or
* guarantee. And that is really all you can expect when you download
* code for free from the Internet.
*
* I think it is really sad that disclaimers like this seem to be necessary.
* If people only had a little bit more common sense, and didn't come
* whining like little children every time something happens....
*/
/*
* Version history:
* Version 0.0, 2002-08-30
* First written.
* Version 0.1, 2002-09-03
* Added disclaimer. Improved self-tests.
* Version 0.2, 2002-09-09
* Removed last non-portabilities. Default now works completely within
* the C standard. UInt32 can be larger than 32 bits without problems.
* Version 0.3, 2002-09-28
* Bugfix: use <string.h> instead of <memory.h> to adhere to ANSI/ISO.
* Rename BIG_ENDIAN macro to CPU_IS_BIG_ENDIAN. The gcc library
* header <string.h> already defines BIG_ENDIAN, even though it is not
* supposed to.
*/
/*
* Minimum set of include files.
* You should not need any application-specific include files for this code.
* In fact, adding you own header files could break one of the many macros or
* functions in this file. Be very careful.
* Standard include files will probably be ok.
*/
#include <qstring.h> /* for memset(), memcpy(), and memcmp() */
#include "twofish.h"
/*
* PLATFORM FIXES
* ==============
*
* Fix the type definitions in twofish.h first!
*
* The following definitions have to be fixed for each particular platform
* you work on. If you have a multi-platform program, you no doubt have
* portable definitions that you can substitute here without changing the
* rest of the code.
*/
/*
* Function called if something is fatally wrong with the implementation.
* This fatal function is called when a coding error is detected in the
* Twofish implementation, or when somebody passes an obviously erroneous
* parameter to this implementation. There is not much you can do when
* the code contains bugs, so we just stop.
*
* The argument is a string. Ideally the fatal function prints this string
* as an error message. Whatever else this function does, it should never
* return. A typical implementation would stop the program completely after
* printing the error message.
*
* This default implementation is not very useful,
* but does not assume anything about your environment.
* It will at least let you know something is wrong....
* I didn't want to include any libraries to print and error or so,
* as this makes the code much harder to integrate in a project.
*
* Note that the Twofish_fatal function may not return to the caller.
* Unfortunately this is not something the self-test can test for,
* so you have to make sure of this yourself.
*
* If you want to call an external function, be careful about including
* your own header files here. This code uses a lot of macros, and your
* header file could easily break it. Maybe the best solution is to use
* a separate extern statement for your fatal function.
*/
//#define Twofish_fatal(pmsgx) { MessageBox(GetDesktopWindow(), _T(pmsgx), _T("Twofish Fatal Error"), MB_OK); }
/*
* The rest of the settings are not important for the functionality
* of this Twofish implementation. That is, their default settings
* work on all platforms. You can change them to improve the
* speed of the implementation on your platform. Erroneous settings
* will result in erroneous implementations, but the self-test should
* catch those.
*/
/*
* Macros to rotate a Twofish_UInt32 value left or right by the
* specified number of bits. This should be a 32-bit rotation,
* and not rotation of, say, 64-bit values.
*
* Every encryption or decryption operation uses 32 of these rotations,
* so it is a good idea to make these macros efficient.
*
* This fully portable definition has one piece of tricky stuff.
* The UInt32 might be larger than 32 bits, so we have to mask
* any higher bits off. The simplest way to do this is to 'and' the
* value first with 0xffffffff and then shift it right. An optimising
* compiler that has a 32-bit type can optimise this 'and' away.
*
* Unfortunately there is no portable way of writing the constant
* 0xffffffff. You don't know which suffix to use (U, or UL?)
* The quint32_MASK definition uses a bit of trickery. Shift-left
* is only defined if the shift amount is strictly less than the size
* of the UInt32, so we can't use (1<<32). The answer it to take the value
* 2, cast it to a UInt32, shift it left 31 positions, and subtract one.
* Another example of how to make something very simple extremely difficult.
* I hate C.
*
* The rotation macros are straightforward.
* They are only applied to UInt32 values, which are _unsigned_
* so the >> operator must do a logical shift that brings in zeroes.
* On most platforms you will only need to optimise the ROL32 macro; the
* ROR32 macro is not inefficient on an optimising compiler as all rotation
* amounts in this code are known at compile time.
*
* On many platforms there is a faster solution.
* For example, MS compilers have the __rotl and __rotr functions
* that generate x86 rotation instructions.
*/
#define quint32_MASK ( (((Twofish_UInt32)2)<<31) - 1 )
#ifndef _MSC_VER
#define ROL32(x,n) ( (x)<<(n) | ((x) & quint32_MASK) >> (32-(n)) )
#define ROR32(x,n) ( (x)>>(n) | ((x) & quint32_MASK) << (32-(n)) )
#else
#define ROL32(x,n) (_lrotl((x), (n)))
#define ROR32(x,n) (_lrotr((x), (n)))
#endif
/*
* Select data type for q-table entries.
*
* Larger entry types cost more memory (1.5 kB), and might be faster
* or slower depending on the CPU and compiler details.
*
* This choice only affects the static data size and the key setup speed.
* Functionality, expanded key size, or encryption speed are not affected.
* Define to 1 to get large q-table entries.
*/
#define LARGE_Q_TABLE 0 /* default = 0 */
/*
* Method to select a single byte from a UInt32.
* WARNING: non-portable code if set; might not work on all platforms.
*
* Inside the inner loop of Twofish it is necessary to access the 4
* individual bytes of a UInt32. This can be done using either shifts
* and masks, or memory accesses.
*
* Set to 0 to use shift and mask operations for the byte selection.
* This is more ALU intensive. It is also fully portable.
*
* Set to 1 to use memory accesses. The UInt32 is stored in memory and
* the individual bytes are read from memory one at a time.
* This solution is more memory-intensive, and not fully portable.
* It might be faster on your platform, or not. If you use this option,
* make sure you set the CPU_IS_BIG_ENDIAN flag appropriately.
*
* This macro does not affect the conversion of the inputs and outputs
* of the cipher. See the CONVERT_USING_CASTS macro for that.
*/
#define SELECT_BYTE_FROM_quint32_IN_MEMORY 0 /* default = 0 */
/*
* Method used to read the input and write the output.
* WARNING: non-portable code if set; might not work on all platforms.
*
* Twofish operates on 32-bit words. The input to the cipher is
* a byte array, as is the output. The portable method of doing the
* conversion is a bunch of rotate and mask operations, but on many
* platforms it can be done faster using a cast.
* This only works if your CPU allows UInt32 accesses to arbitrary Byte
* addresses.
*
* Set to 0 to use the shift and mask operations. This is fully
* portable. .
*
* Set to 1 to use a cast. The Byte * is cast to a UInt32 *, and a
* UInt32 is read. If necessary (as indicated by the CPU_IS_BIG_ENDIAN
* macro) the byte order in the UInt32 is swapped. The reverse is done
* to write the output of the encryption/decryption. Make sure you set
* the CPU_IS_BIG_ENDIAN flag appropriately.
* This option does not work unless a UInt32 is exactly 32 bits.
*
* This macro only changes the reading/writing of the plaintext/ciphertext.
* See the SELECT_BYTE_FROM_quint32_IN_MEMORY to affect the way in which
* a UInt32 is split into 4 bytes for the S-box selection.
*/
#define CONVERT_USING_CASTS 0 /* default = 0 */
/*
* Endianness switch.
* Only relevant if SELECT_BYTE_FROM_quint32_IN_MEMORY or
* CONVERT_USING_CASTS is set.
*
* Set to 1 on a big-endian machine, and to 0 on a little-endian machine.
* Twofish uses the little-endian convention (least significant byte first)
* and big-endian machines (using most significant byte first)
* have to do a few conversions.
*
* CAUTION: This code has never been tested on a big-endian machine,
* because I don't have access to one. Feedback appreciated.
*/
#define CPU_IS_BIG_ENDIAN 0
/*
* Macro to reverse the order of the bytes in a UInt32.
* Used to convert to little-endian on big-endian machines.
* This macro is always tested, but only used in the encryption and
* decryption if CONVERT_USING_CASTS, and CPU_IS_BIG_ENDIAN
* are both set. In other words: this macro is only speed-critical if
* both these flags have been set.
*
* This default definition of SWAP works, but on many platforms there is a
* more efficient implementation.
*/
#define BSWAP(x) (ROL32((x),8)&0x00ff00ff | ROR32((x),8) & 0xff00ff00)
/*
* END OF PLATFORM FIXES
* =====================
*
* You should not have to touch the rest of this file.
*/
/*
* Convert the external type names to some that are easier to use inside
* this file. I didn't want to use the names Byte and UInt32 in the
* header file, because many programs already define them and using two
* conventions at once can be very difficult.
* Don't change these definitions! Change the originals
* in twofish.h instead.
*/
/* A Byte must be an unsigned integer, 8 bits long. */
// typedef Twofish_Byte Byte;
/* A UInt32 must be an unsigned integer at least 32 bits long. */
// typedef Twofish_UInt32 UInt32;
/*
* Define a macro ENDIAN_CONVERT.
*
* We define a macro ENDIAN_CONVERT that performs a BSWAP on big-endian
* machines, and is the identity function on little-endian machines.
* The code then uses this macro without considering the endianness.
*/
#if CPU_IS_BIG_ENDIAN
#define ENDIAN_CONVERT(x) BSWAP(x)
#else
#define ENDIAN_CONVERT(x) (x)
#endif
/*
* Compute byte offset within a UInt32 stored in memory.
*
* This is only used when SELECT_BYTE_FROM_quint32_IN_MEMORY is set.
*
* The input is the byte number 0..3, 0 for least significant.
* Note the use of sizeof() to support UInt32 types that are larger
* than 4 bytes.
*/
#if CPU_IS_BIG_ENDIAN
#define BYTE_OFFSET( n ) (sizeof(Twofish_UInt32) - 1 - (n) )
#else
#define BYTE_OFFSET( n ) (n)
#endif
/*
* Macro to get Byte no. b from UInt32 value X.
* We use two different definition, depending on the settings.
*/
#if SELECT_BYTE_FROM_quint32_IN_MEMORY
/* Pick the byte from the memory in which X is stored. */
#define SELECT_BYTE( X, b ) (((Twofish_Byte *)(&(X)))[BYTE_OFFSET(b)])
#else
/* Portable solution: Pick the byte directly from the X value. */
#define SELECT_BYTE( X, b ) (((X) >> (8*(b))) & 0xff)
#endif
/* Some shorthands because we use byte selection in large formulae. */
#define b0(X) SELECT_BYTE((X),0)
#define b1(X) SELECT_BYTE((X),1)
#define b2(X) SELECT_BYTE((X),2)
#define b3(X) SELECT_BYTE((X),3)
/*
* We need macros to load and store UInt32 from/to byte arrays
* using the least-significant-byte-first convention.
*
* GET32( p ) gets a UInt32 in lsb-first form from four bytes pointed to
* by p.
* PUT32( v, p ) writes the UInt32 value v at address p in lsb-first form.
*/
#if CONVERT_USING_CASTS
/* Get UInt32 from four bytes pointed to by p. */
#define GET32( p ) ENDIAN_CONVERT( *((Twofish_UInt32 *)(p)) )
/* Put UInt32 into four bytes pointed to by p */
#define PUT32( v, p ) *((Twofish_UInt32 *)(p)) = ENDIAN_CONVERT(v)
#else
/* Get UInt32 from four bytes pointed to by p. */
#define GET32( p ) \
( \
(Twofish_UInt32)((p)[0]) \
| (Twofish_UInt32)((p)[1])<< 8 \
| (Twofish_UInt32)((p)[2])<<16 \
| (Twofish_UInt32)((p)[3])<<24 \
)
/* Put UInt32 into four bytes pointed to by p */
#define PUT32( v, p ) \
(p)[0] = (Twofish_Byte)(((v) ) & 0xff); \
(p)[1] = (Twofish_Byte)(((v) >> 8) & 0xff); \
(p)[2] = (Twofish_Byte)(((v) >> 16) & 0xff); \
(p)[3] = (Twofish_Byte)(((v) >> 24) & 0xff)
#endif
void Twofish_fatal(char* msg){
qCritical("Twofish: Fatal Error");
exit(1);
}
/*
* Test the platform-specific macros.
* This function tests the macros defined so far to make sure the
* definitions are appropriate for this platform.
* If you make any mistake in the platform configuration, this should detect
* that and inform you what went wrong.
* Somewhere, someday, this is going to save somebody a lot of time,
* because misbehaving macros are hard to debug.
*/
static void test_platform()
{
/* Buffer with test values. */
Twofish_Byte buf[] = {0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc, 0xde, 0};
Twofish_UInt32 C;
Twofish_UInt32 x,y;
int i;
/*
* Some sanity checks on the types that can't be done in compile time.
* A smart compiler will just optimise these tests away.
* The pre-processor doesn't understand different types, so we cannot
* do these checks in compile-time.
*
* I hate C.
*
* The first check in each case is to make sure the size is correct.
* The second check is to ensure that it is an unsigned type.
*/
if( ((Twofish_UInt32)((Twofish_UInt32)1 << 31) == 0) || ((Twofish_UInt32)-1 < 0 ))
{
Twofish_fatal( "Twofish code: Twofish_UInt32 type not suitable" );
}
if( (sizeof( Twofish_Byte ) != 1) || (((Twofish_Byte)-1) < 0) )
{
Twofish_fatal( "Twofish code: Twofish_Byte type not suitable" );
}
/*
* Sanity-check the endianness conversions.
* This is just an aid to find problems. If you do the endianness
* conversion macros wrong you will fail the full cipher test,
* but that does not help you find the error.
* Always make it easy to find the bugs!
*
* Detail: There is no fully portable way of writing UInt32 constants,
* as you don't know whether to use the U or UL suffix. Using only U you
* might only be allowed 16-bit constants. Using UL you might get 64-bit
* constants which cannot be stored in a UInt32 without warnings, and
* which generally behave subtly different from a true UInt32.
* As long as we're just comparing with the constant,
* we can always use the UL suffix and at worst lose some efficiency.
* I use a separate '32-bit constant' macro in most of my other code.
*
* I hate C.
*
* Start with testing GET32. We test it on all positions modulo 4
* to make sure we can handly any position of inputs. (Some CPUs
* do not allow non-aligned accesses which we would do if you used
* the CONVERT_USING_CASTS option.
*/
if( (GET32( buf ) != 0x78563412UL) || (GET32(buf+1) != 0x9a785634UL)
|| (GET32( buf+2 ) != 0xbc9a7856UL) || (GET32(buf+3) != 0xdebc9a78UL) )
{
Twofish_fatal( "Twofish code: GET32 not implemented properly" );
}
/*
* We can now use GET32 to test PUT32.
* We don't test the shifted versions. If GET32 can do that then
* so should PUT32.
*/
C = GET32( buf );
PUT32( 3*C, buf );
if( GET32( buf ) != 0x69029c36UL )
{
Twofish_fatal( "Twofish code: PUT32 not implemented properly" );
}
/* Test ROL and ROR */
for( i=1; i<32; i++ )
{
/* Just a simple test. */
x = ROR32( C, i );
y = ROL32( C, i );
x ^= (C>>i) ^ (C<<(32-i));
y ^= (C<<i) ^ (C>>(32-i));
x |= y;
/*
* Now all we check is that x is zero in the least significant
* 32 bits. Using the UL suffix is safe here, as it doesn't matter
* if we get a larger type.
*/
if( (x & 0xffffffffUL) != 0 )
{
Twofish_fatal( "Twofish ROL or ROR not properly defined." );
}
}
/* Test the BSWAP macro */
if( BSWAP(C) != 0x12345678UL )
{
/*
* The BSWAP macro should always work, even if you are not using it.
* A smart optimising compiler will just remove this entire test.
*/
Twofish_fatal( "BSWAP not properly defined." );
}
/* And we can test the b<i> macros which use SELECT_BYTE. */
if( (b0(C)!=0x12) || (b1(C) != 0x34) || (b2(C) != 0x56) || (b3(C) != 0x78) )
{
/*
* There are many reasons why this could fail.
* Most likely is that CPU_IS_BIG_ENDIAN has the wrong value.
*/
Twofish_fatal( "Twofish code: SELECT_BYTE not implemented properly" );
}
}
/*
* Finally, we can start on the Twofish-related code.
* You really need the Twofish specifications to understand this code. The
* best source is the Twofish book:
* "The Twofish Encryption Algorithm", by Bruce Schneier, John Kelsey,
* Doug Whiting, David Wagner, Chris Hall, and Niels Ferguson.
* you can also use the AES submission document of Twofish, which is
* available from my list of publications on my personal web site at
* http://niels.ferguson.net/.
*
* The first thing we do is write the testing routines. This is what the
* implementation has to satisfy in the end. We only test the external
* behaviour of the implementation of course.
*/
/*
* Perform a single self test on a (plaintext,ciphertext,key) triple.
* Arguments:
* key array of key bytes
* key_len length of key in bytes
* p plaintext
* c ciphertext
*/
static void test_vector( Twofish_Byte key[], int key_len, Twofish_Byte p[16], Twofish_Byte c[16] )
{
Twofish_Byte tmp[16]; /* scratch pad. */
Twofish_key xkey; /* The expanded key */
int i;
/* Prepare the key */
Twofish_prepare_key( key, key_len, &xkey );
/*
* We run the test twice to ensure that the xkey structure
* is not damaged by the first encryption.
* Those are hideous bugs to find if you get them in an application.
*/
for( i=0; i<2; i++ )
{
/* Encrypt and test */
Twofish_encrypt( &xkey, p, tmp );
if( memcmp( c, tmp, 16 ) != 0 )
{
Twofish_fatal( "Twofish encryption failure" );
}
/* Decrypt and test */
Twofish_decrypt( &xkey, c, tmp );
if( memcmp( p, tmp, 16 ) != 0 )
{
Twofish_fatal( "Twofish decryption failure" );
}
}
/* The test keys are not secret, so we don't need to wipe xkey. */
}
/*
* Check implementation using three (key,plaintext,ciphertext)
* test vectors, one for each major key length.
*
* This is an absolutely minimal self-test.
* This routine does not test odd-sized keys.
*/
static void test_vectors()
{
/*
* We run three tests, one for each major key length.
* These test vectors come from the Twofish specification.
* One encryption and one decryption using randomish data and key
* will detect almost any error, especially since we generate the
* tables ourselves, so we don't have the problem of a single
* damaged table entry in the source.
*/
/* 128-bit test is the I=3 case of section B.2 of the Twofish book. */
static Twofish_Byte k128[] = {
0x9F, 0x58, 0x9F, 0x5C, 0xF6, 0x12, 0x2C, 0x32,
0xB6, 0xBF, 0xEC, 0x2F, 0x2A, 0xE8, 0xC3, 0x5A,
};
static Twofish_Byte p128[] = {
0xD4, 0x91, 0xDB, 0x16, 0xE7, 0xB1, 0xC3, 0x9E,
0x86, 0xCB, 0x08, 0x6B, 0x78, 0x9F, 0x54, 0x19
};
static Twofish_Byte c128[] = {
0x01, 0x9F, 0x98, 0x09, 0xDE, 0x17, 0x11, 0x85,
0x8F, 0xAA, 0xC3, 0xA3, 0xBA, 0x20, 0xFB, 0xC3
};
/* 192-bit test is the I=4 case of section B.2 of the Twofish book. */
static Twofish_Byte k192[] = {
0x88, 0xB2, 0xB2, 0x70, 0x6B, 0x10, 0x5E, 0x36,
0xB4, 0x46, 0xBB, 0x6D, 0x73, 0x1A, 0x1E, 0x88,
0xEF, 0xA7, 0x1F, 0x78, 0x89, 0x65, 0xBD, 0x44
};
static Twofish_Byte p192[] = {
0x39, 0xDA, 0x69, 0xD6, 0xBA, 0x49, 0x97, 0xD5,
0x85, 0xB6, 0xDC, 0x07, 0x3C, 0xA3, 0x41, 0xB2
};
static Twofish_Byte c192[] = {
0x18, 0x2B, 0x02, 0xD8, 0x14, 0x97, 0xEA, 0x45,
0xF9, 0xDA, 0xAC, 0xDC, 0x29, 0x19, 0x3A, 0x65
};
/* 256-bit test is the I=4 case of section B.2 of the Twofish book. */
static Twofish_Byte k256[] = {
0xD4, 0x3B, 0xB7, 0x55, 0x6E, 0xA3, 0x2E, 0x46,
0xF2, 0xA2, 0x82, 0xB7, 0xD4, 0x5B, 0x4E, 0x0D,
0x57, 0xFF, 0x73, 0x9D, 0x4D, 0xC9, 0x2C, 0x1B,
0xD7, 0xFC, 0x01, 0x70, 0x0C, 0xC8, 0x21, 0x6F
};
static Twofish_Byte p256[] = {
0x90, 0xAF, 0xE9, 0x1B, 0xB2, 0x88, 0x54, 0x4F,
0x2C, 0x32, 0xDC, 0x23, 0x9B, 0x26, 0x35, 0xE6
};
static Twofish_Byte c256[] = {
0x6C, 0xB4, 0x56, 0x1C, 0x40, 0xBF, 0x0A, 0x97,
0x05, 0x93, 0x1C, 0xB6, 0xD4, 0x08, 0xE7, 0xFA
};
/* Run the actual tests. */
test_vector( k128, 16, p128, c128 );
test_vector( k192, 24, p192, c192 );
test_vector( k256, 32, p256, c256 );
}
/*
* Perform extensive test for a single key size.
*
* Test a single key size against the test vectors from section
* B.2 in the Twofish book. This is a sequence of 49 encryptions
* and decryptions. Each plaintext is equal to the ciphertext of
* the previous encryption. The key is made up from the ciphertext
* two and three encryptions ago. Both plaintext and key start
* at the zero value.
* We should have designed a cleaner recurrence relation for
* these tests, but it is too late for that now. At least we learned
* how to do it better next time.
* For details see appendix B of the book.
*
* Arguments:
* key_len Number of bytes of key
* final_value Final plaintext value after 49 iterations
*/
static void test_sequence( int key_len, Twofish_Byte final_value[] )
{
Twofish_Byte buf[ (50+3)*16 ]; /* Buffer to hold our computation values. */
Twofish_Byte tmp[16]; /* Temp for testing the decryption. */
Twofish_key xkey; /* The expanded key */
int i;
Twofish_Byte * p;
/* Wipe the buffer */
memset( buf, 0, sizeof( buf ) );
/*
* Because the recurrence relation is done in an inconvenient manner
* we end up looping backwards over the buffer.
*/
/* Pointer in buffer points to current plaintext. */
p = &buf[50*16];
for( i=1; i<50; i++ )
{
/*
* Prepare a key.
* This automatically checks that key_len is valid.
*/
Twofish_prepare_key( p+16, key_len, &xkey );
/* Compute the next 16 bytes in the buffer */
Twofish_encrypt( &xkey, p, p-16 );
/* Check that the decryption is correct. */
Twofish_decrypt( &xkey, p-16, tmp );
if( memcmp( tmp, p, 16 ) != 0 )
{
Twofish_fatal( "Twofish decryption failure in sequence" );
}
/* Move on to next 16 bytes in the buffer. */
p -= 16;
}
/* And check the final value. */
if( memcmp( p, final_value, 16 ) != 0 )
{
Twofish_fatal( "Twofish encryption failure in sequence" );
}
/* None of the data was secret, so there is no need to wipe anything. */
}
/*
* Run all three sequence tests from the Twofish test vectors.
*
* This checks the most extensive test vectors currently available
* for Twofish. The data is from the Twofish book, appendix B.2.
*/
static void test_sequences()
{
static Twofish_Byte r128[] = {
0x5D, 0x9D, 0x4E, 0xEF, 0xFA, 0x91, 0x51, 0x57,
0x55, 0x24, 0xF1, 0x15, 0x81, 0x5A, 0x12, 0xE0
};
static Twofish_Byte r192[] = {
0xE7, 0x54, 0x49, 0x21, 0x2B, 0xEE, 0xF9, 0xF4,
0xA3, 0x90, 0xBD, 0x86, 0x0A, 0x64, 0x09, 0x41
};
static Twofish_Byte r256[] = {
0x37, 0xFE, 0x26, 0xFF, 0x1C, 0xF6, 0x61, 0x75,
0xF5, 0xDD, 0xF4, 0xC3, 0x3B, 0x97, 0xA2, 0x05
};
/* Run the three sequence test vectors */
test_sequence( 16, r128 );
test_sequence( 24, r192 );
test_sequence( 32, r256 );
}
/*
* Test the odd-sized keys.
*
* Every odd-sized key is equivalent to a one of 128, 192, or 256 bits.
* The equivalent key is found by padding at the end with zero bytes
* until a regular key size is reached.
*
* We just test that the key expansion routine behaves properly.
* If the expanded keys are identical, then the encryptions and decryptions
* will behave the same.
*/
static void test_odd_sized_keys()
{
Twofish_Byte buf[32];
Twofish_key xkey;
Twofish_key xkey_two;
int i;
/*
* We first create an all-zero key to use as PRNG key.
* Normally we would not have to fill the buffer with zeroes, as we could
* just pass a zero key length to the Twofish_prepare_key function.
* However, this relies on using odd-sized keys, and those are just the
* ones we are testing here. We can't use an untested function to test
* itself.
*/
memset( buf, 0, sizeof( buf ) );
Twofish_prepare_key( buf, 16, &xkey );
/* Fill buffer with pseudo-random data derived from two encryptions */
Twofish_encrypt( &xkey, buf, buf );
Twofish_encrypt( &xkey, buf, buf+16 );
/* Create all possible shorter keys that are prefixes of the buffer. */
for( i=31; i>=0; i-- )
{
/* Set a byte to zero. This is the new padding byte */
buf[i] = 0;
/* Expand the key with only i bytes of length */
Twofish_prepare_key( buf, i, &xkey );
/* Expand the corresponding padded key of regular length */
Twofish_prepare_key( buf, i<=16 ? 16 : (i<= 24 ? 24 : 32), &xkey_two );
/* Compare the two */
if( memcmp( &xkey, &xkey_two, sizeof( xkey ) ) != 0 )
{
Twofish_fatal( "Odd sized keys do not expand properly" );
}
}
/* None of the key values are secret, so we don't need to wipe them. */
}
/*
* Test the Twofish implementation.
*
* This routine runs all the self tests, in order of importance.
* It is called by the Twofish_initialise routine.
*
* In almost all applications the cost of running the self tests during
* initialisation is insignificant, especially
* compared to the time it takes to load the application from disk.
* If you are very pressed for initialisation performance,
* you could remove some of the tests. Make sure you did run them
* once in the software and hardware configuration you are using.
*/
static void self_test()
{
/* The three test vectors form an absolute minimal test set. */
test_vectors();
/*
* If at all possible you should run these tests too. They take
* more time, but provide a more thorough coverage.
*/
test_sequences();
/* Test the odd-sized keys. */
test_odd_sized_keys();
}
/*
* And now, the actual Twofish implementation.
*
* This implementation generates all the tables during initialisation.
* I don't like large tables in the code, especially since they are easily
* damaged in the source without anyone noticing it. You need code to
* generate them anyway, and this way all the code is close together.
* Generating them in the application leads to a smaller executable
* (the code is smaller than the tables it generates) and a
* larger static memory footprint.
*
* Twofish can be implemented in many ways. I have chosen to
* use large tables with a relatively long key setup time.
* If you encrypt more than a few blocks of data it pays to pre-compute
* as much as possible. This implementation is relatively inefficient for
* applications that need to re-key every block or so.
*/
/*
* We start with the t-tables, directly from the Twofish definition.
* These are nibble-tables, but merging them and putting them two nibbles
* in one byte is more work than it is worth.
*/
static Twofish_Byte t_table[2][4][16] = {
{
{0x8,0x1,0x7,0xD,0x6,0xF,0x3,0x2,0x0,0xB,0x5,0x9,0xE,0xC,0xA,0x4},
{0xE,0xC,0xB,0x8,0x1,0x2,0x3,0x5,0xF,0x4,0xA,0x6,0x7,0x0,0x9,0xD},
{0xB,0xA,0x5,0xE,0x6,0xD,0x9,0x0,0xC,0x8,0xF,0x3,0x2,0x4,0x7,0x1},
{0xD,0x7,0xF,0x4,0x1,0x2,0x6,0xE,0x9,0xB,0x3,0x0,0x8,0x5,0xC,0xA}
},
{
{0x2,0x8,0xB,0xD,0xF,0x7,0x6,0xE,0x3,0x1,0x9,0x4,0x0,0xA,0xC,0x5},
{0x1,0xE,0x2,0xB,0x4,0xC,0x3,0x7,0x6,0xD,0xA,0x5,0xF,0x9,0x0,0x8},
{0x4,0xC,0x7,0x5,0x1,0x6,0x9,0xA,0x0,0xE,0xD,0x8,0x2,0xB,0x3,0xF},
{0xB,0x9,0x5,0x1,0xC,0x3,0xD,0xE,0x6,0x4,0x7,0xF,0x2,0x0,0x8,0xA}
}
};
/* A 1-bit rotation of 4-bit values. Input must be in range 0..15 */
#define ROR4BY1( x ) (((x)>>1) | (((x)<<3) & 0x8) )
/*
* The q-boxes are only used during the key schedule computations.
* These are 8->8 bit lookup tables. Some CPUs prefer to have 8->32 bit
* lookup tables as it is faster to load a 32-bit value than to load an
* 8-bit value and zero the rest of the register.
* The LARGE_Q_TABLE switch allows you to choose 32-bit entries in
* the q-tables. Here we just define the Qtype which is used to store
* the entries of the q-tables.
*/
#if LARGE_Q_TABLE
typedef Twofish_UInt32 Qtype;
#else
typedef Twofish_Byte Qtype;
#endif
/*
* The actual q-box tables.
* There are two q-boxes, each having 256 entries.
*/
static Qtype q_table[2][256];
/*
* Now the function that converts a single t-table into a q-table.
*
* Arguments:
* t[4][16] : four 4->4bit lookup tables that define the q-box
* q[256] : output parameter: the resulting q-box as a lookup table.
*/
static void make_q_table( Twofish_Byte t[4][16], Qtype q[256] )
{
int ae,be,ao,bo; /* Some temporaries. */
int i;
/* Loop over all input values and compute the q-box result. */
for( i=0; i<256; i++ ) {
/*
* This is straight from the Twofish specifications.
*
* The ae variable is used for the a_i values from the specs
* with even i, and ao for the odd i's. Similarly for the b's.
*/
ae = i>>4; be = i&0xf;
ao = ae ^ be; bo = ae ^ ROR4BY1(be) ^ ((ae<<3)&8);
ae = t[0][ao]; be = t[1][bo];
ao = ae ^ be; bo = ae ^ ROR4BY1(be) ^ ((ae<<3)&8);
ae = t[2][ao]; be = t[3][bo];
/* Store the result in the q-box table, the cast avoids a warning. */
q[i] = (Qtype) ((be<<4) | ae);
}
}
/*
* Initialise both q-box tables.
*/
static void initialise_q_boxes() {
/* Initialise each of the q-boxes using the t-tables */