📄 aesopt.h
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/*
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Copyright (c) 2003, Dr Brian Gladman, Worcester, UK. All rights reserved.
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ALTERNATIVELY, provided that this notice is retained in full, this product
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---------------------------------------------------------------------------
Issue 28/01/2004
My thanks go to Dag Arne Osvik for devising the schemes used here for key
length derivation from the form of the key schedule
This file contains the compilation options for AES (Rijndael) and code
that is common across encryption, key scheduling and table generation.
OPERATION
These source code files implement the AES algorithm Rijndael designed by
Joan Daemen and Vincent Rijmen. This version is designed for the standard
block size of 16 bytes and for key sizes of 128, 192 and 256 bits (16, 24
and 32 bytes).
This version is designed for flexibility and speed using operations on
32-bit words rather than operations on bytes. It can be compiled with
either big or little endian internal byte order but is faster when the
native byte order for the processor is used.
THE CIPHER INTERFACE
The cipher interface is implemented as an array of bytes in which lower
AES bit sequence indexes map to higher numeric significance within bytes.
aes_08t (an unsigned 8-bit type)
aes_32t (an unsigned 32-bit type)
struct aes_encrypt_ctx (structure for the cipher encryption context)
struct aes_decrypt_ctx (structure for the cipher decryption context)
aes_rval the function return type
C subroutine calls:
aes_rval aes_encrypt_key128(const unsigned char *key, aes_encrypt_ctx cx[1]);
aes_rval aes_encrypt_key192(const unsigned char *key, aes_encrypt_ctx cx[1]);
aes_rval aes_encrypt_key256(const unsigned char *key, aes_encrypt_ctx cx[1]);
aes_rval aes_encrypt(const unsigned char *in, unsigned char *out,
const aes_encrypt_ctx cx[1]);
aes_rval aes_decrypt_key128(const unsigned char *key, aes_decrypt_ctx cx[1]);
aes_rval aes_decrypt_key192(const unsigned char *key, aes_decrypt_ctx cx[1]);
aes_rval aes_decrypt_key256(const unsigned char *key, aes_decrypt_ctx cx[1]);
aes_rval aes_decrypt(const unsigned char *in, unsigned char *out,
const aes_decrypt_ctx cx[1]);
IMPORTANT NOTE: If you are using this C interface with dynamic tables make sure that
you call genTabs() before AES is used so that the tables are initialised.
C++ aes class subroutines:
Class AESencrypt for encryption
Construtors:
AESencrypt(void)
AESencrypt(const unsigned char *key) - 128 bit key
Members:
aes_rval key128(const unsigned char *key)
aes_rval key192(const unsigned char *key)
aes_rval key256(const unsigned char *key)
aes_rval encrypt(const unsigned char *in, unsigned char *out) const
Class AESdecrypt for encryption
Construtors:
AESdecrypt(void)
AESdecrypt(const unsigned char *key) - 128 bit key
Members:
aes_rval key128(const unsigned char *key)
aes_rval key192(const unsigned char *key)
aes_rval key256(const unsigned char *key)
aes_rval decrypt(const unsigned char *in, unsigned char *out) const
COMPILATION
The files used to provide AES (Rijndael) are
a. aes.h for the definitions needed for use in C.
b. aescpp.h for the definitions needed for use in C++.
c. aesopt.h for setting compilation options (also includes common code).
d. aescrypt.c for encryption and decrytpion, or
e. aeskey.c for key scheduling.
f. aestab.c for table loading or generation.
g. aescrypt.asm for encryption and decryption using assembler code.
h. aescrypt.mmx.asm for encryption and decryption using MMX assembler.
To compile AES (Rijndael) for use in C code use aes.h and set the
defines here for the facilities you need (key lengths, encryption
and/or decryption). Do not define AES_DLL or AES_CPP. Set the options
for optimisations and table sizes here.
To compile AES (Rijndael) for use in in C++ code use aescpp.h but do
not define AES_DLL
To compile AES (Rijndael) in C as a Dynamic Link Library DLL) use
aes.h and include the AES_DLL define.
CONFIGURATION OPTIONS (here and in aes.h)
a. set AES_DLL in aes.h if AES (Rijndael) is to be compiled as a DLL
b. You may need to set PLATFORM_BYTE_ORDER to define the byte order.
c. If you want the code to run in a specific internal byte order, then
ALGORITHM_BYTE_ORDER must be set accordingly.
d. set other configuration options decribed below.
*/
#if !defined( _AESOPT_H )
#define _AESOPT_H
#include "aes.h"
/* CONFIGURATION - USE OF DEFINES
Later in this section there are a number of defines that control the
operation of the code. In each section, the purpose of each define is
explained so that the relevant form can be included or excluded by
setting either 1's or 0's respectively on the branches of the related
#if clauses.
PLATFORM SPECIFIC INCLUDES AND BYTE ORDER IN 32-BIT WORDS
To obtain the highest speed on processors with 32-bit words, this code
needs to determine the byte order of the target machine. The following
block of code is an attempt to capture the most obvious ways in which
various environemnts define byte order. It may well fail, in which case
the definitions will need to be set by editing at the points marked
**** EDIT HERE IF NECESSARY **** below. My thanks go to Peter Gutmann
for his assistance with this endian detection nightmare.
*/
#define BRG_LITTLE_ENDIAN 1234 /* byte 0 is least significant (i386) */
#define BRG_BIG_ENDIAN 4321 /* byte 0 is most significant (mc68k) */
#if defined(__GNUC__) || defined(__GNU_LIBRARY__)
# if defined(__FreeBSD__) || defined(__OpenBSD__)
# include <sys/endian.h>
# elif defined( BSD ) && BSD >= 199103
# include <machine/endian.h>
# elif defined(__APPLE__)
# if defined(__BIG_ENDIAN__) && !defined( BIG_ENDIAN )
# define BIG_ENDIAN
# elif defined(__LITTLE_ENDIAN__) && !defined( LITTLE_ENDIAN )
# define LITTLE_ENDIAN
# endif
# else
# include <endian.h>
# if defined(__BEOS__)
# include <byteswap.h>
# endif
# endif
#endif
#if !defined(PLATFORM_BYTE_ORDER)
# if defined(LITTLE_ENDIAN) || defined(BIG_ENDIAN)
# if defined(LITTLE_ENDIAN) && !defined(BIG_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
# elif !defined(LITTLE_ENDIAN) && defined(BIG_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
# elif defined(BYTE_ORDER) && (BYTE_ORDER == LITTLE_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
# elif defined(BYTE_ORDER) && (BYTE_ORDER == BIG_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
# endif
# elif defined(_LITTLE_ENDIAN) || defined(_BIG_ENDIAN)
# if defined(_LITTLE_ENDIAN) && !defined(_BIG_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
# elif !defined(_LITTLE_ENDIAN) && defined(_BIG_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
# elif defined(_BYTE_ORDER) && (_BYTE_ORDER == _LITTLE_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
# elif defined(_BYTE_ORDER) && (_BYTE_ORDER == _BIG_ENDIAN)
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
# endif
# elif defined(__LITTLE_ENDIAN__) || defined(__BIG_ENDIAN__)
# if defined(__LITTLE_ENDIAN__) && !defined(__BIG_ENDIAN__)
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
# elif !defined(__LITTLE_ENDIAN__) && defined(__BIG_ENDIAN__)
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
# elif defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __LITTLE_ENDIAN__)
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
# elif defined(__BYTE_ORDER__) && (__BYTE_ORDER__ == __BIG_ENDIAN__)
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
# endif
# endif
#endif
/* if the platform is still unknown, try to find its byte order */
/* from commonly used machine defines */
#if !defined(PLATFORM_BYTE_ORDER)
#if defined( __alpha__ ) || defined( __alpha ) || defined( i386 ) || \
defined( __i386__ ) || defined( _M_I86 ) || defined( _M_IX86 ) || \
defined( __OS2__ ) || defined( sun386 ) || defined( __TURBOC__ ) || \
defined( vax ) || defined( vms ) || defined( VMS ) || \
defined( __VMS )
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
#elif defined( AMIGA ) || defined( applec ) || defined( __AS400__ ) || \
defined( _CRAY ) || defined( __hppa ) || defined( __hp9000 ) || \
defined( ibm370 ) || defined( mc68000 ) || defined( m68k ) || \
defined( __MRC__ ) || defined( __MVS__ ) || defined( __MWERKS__ ) || \
defined( sparc ) || defined( __sparc) || defined( SYMANTEC_C ) || \
defined( __TANDEM ) || defined( THINK_C ) || defined( __VMCMS__ )
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
#elif 0 /* **** EDIT HERE IF NECESSARY **** */
# define PLATFORM_BYTE_ORDER BRG_LITTLE_ENDIAN
#elif 0 /* **** EDIT HERE IF NECESSARY **** */
# define PLATFORM_BYTE_ORDER BRG_BIG_ENDIAN
#else
# error Please edit aesopt.h (line 234 or 236) to set the platform byte order
#endif
#endif
/* SOME LOCAL DEFINITIONS */
#define NO_TABLES 0
#define ONE_TABLE 1
#define FOUR_TABLES 4
#define NONE 0
#define PARTIAL 1
#define FULL 2
#if defined(bswap32)
#define aes_sw32 bswap32
#elif defined(bswap_32)
#define aes_sw32 bswap_32
#else
#define brot(x,n) (((aes_32t)(x) << n) | ((aes_32t)(x) >> (32 - n)))
#define aes_sw32(x) ((brot((x),8) & 0x00ff00ff) | (brot((x),24) & 0xff00ff00))
#endif
/* 1. FUNCTIONS REQUIRED
This implementation provides subroutines for encryption, decryption
and for setting the three key lengths (separately) for encryption
and decryption. When the assembler code is not being used the following
definition blocks allow the selection of the routines that are to be
included in the compilation.
*/
#if defined( AES_ENCRYPT )
#define ENCRYPTION
#define ENCRYPTION_KEY_SCHEDULE
#endif
#if defined( AES_DECRYPT )
#define DECRYPTION
#define DECRYPTION_KEY_SCHEDULE
#endif
/* 2. ASSEMBLER SUPPORT
This define (which can be on the command line) enables the use of the
assembler code routines for encryption and decryption with the C code
only providing key scheduling
*/
#if 0 && !defined(AES_ASM)
#define AES_ASM
#endif
/* 3. BYTE ORDER WITHIN 32 BIT WORDS
The fundamental data processing units in Rijndael are 8-bit bytes. The
input, output and key input are all enumerated arrays of bytes in which
bytes are numbered starting at zero and increasing to one less than the
number of bytes in the array in question. This enumeration is only used
for naming bytes and does not imply any adjacency or order relationship
from one byte to another. When these inputs and outputs are considered
as bit sequences, bits 8*n to 8*n+7 of the bit sequence are mapped to
byte[n] with bit 8n+i in the sequence mapped to bit 7-i within the byte.
In this implementation bits are numbered from 0 to 7 starting at the
numerically least significant end of each byte (bit n represents 2^n).
However, Rijndael can be implemented more efficiently using 32-bit
words by packing bytes into words so that bytes 4*n to 4*n+3 are placed
into word[n]. While in principle these bytes can be assembled into words
in any positions, this implementation only supports the two formats in
which bytes in adjacent positions within words also have adjacent byte
numbers. This order is called big-endian if the lowest numbered bytes
in words have the highest numeric significance and little-endian if the
opposite applies.
This code can work in either order irrespective of the order used by the
machine on which it runs. Normally the internal byte order will be set
to the order of the processor on which the code is to be run but this
define can be used to reverse this in special situations
NOTE: Assembler code versions rely on PLATFORM_BYTE_ORDER being set
*/
#if 1 || defined(AES_ASM)
#define ALGORITHM_BYTE_ORDER PLATFORM_BYTE_ORDER
#elif 0
#define ALGORITHM_BYTE_ORDER BRG_LITTLE_ENDIAN
#elif 0
#define ALGORITHM_BYTE_ORDER BRG_BIG_ENDIAN
#else
#error The algorithm byte order is not defined
#endif
/* 4. FAST INPUT/OUTPUT OPERATIONS.
On some machines it is possible to improve speed by transferring the
bytes in the input and output arrays to and from the internal 32-bit
variables by addressing these arrays as if they are arrays of 32-bit
words. On some machines this will always be possible but there may
be a large performance penalty if the byte arrays are not aligned on
the normal word boundaries. On other machines this technique will
lead to memory access errors when such 32-bit word accesses are not
properly aligned. The option SAFE_IO avoids such problems but will
often be slower on those machines that support misaligned access
(especially so if care is taken to align the input and output byte
arrays on 32-bit word boundaries). If SAFE_IO is not defined it is
assumed that access to byte arrays as if they are arrays of 32-bit
words will not cause problems when such accesses are misaligned.
*/
#if 1 && !defined(_MSC_VER)
#define SAFE_IO
#endif
/* 5. LOOP UNROLLING
The code for encryption and decrytpion cycles through a number of rounds
that can be implemented either in a loop or by expanding the code into a
long sequence of instructions, the latter producing a larger program but
one that will often be much faster. The latter is called loop unrolling.
There are also potential speed advantages in expanding two iterations in
a loop with half the number of iterations, which is called partial loop
unrolling. The following options allow partial or full loop unrolling
to be set independently for encryption and decryption
*/
#if 1
#define ENC_UNROLL FULL
#elif 0
#define ENC_UNROLL PARTIAL
#else
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