; --------------------------------------------------------------------------- ; Copyright (c) 1998-2007, Brian Gladman, Worcester, UK. All rights reserved. ; ; LICENSE TERMS ; ; The free distribution and use of this software is allowed (with or without ; changes) provided that: ; ; 1. source code distributions include the above copyright notice, this ; list of conditions and the following disclaimer; ; ; 2. binary distributions include the above copyright notice, this list ; of conditions and the following disclaimer in their documentation; ; ; 3. the name of the copyright holder is not used to endorse products ; built using this software without specific written permission. ; ; DISCLAIMER ; ; This software is provided 'as is' with no explicit or implied warranties ; in respect of its properties, including, but not limited to, correctness ; and/or fitness for purpose. ; --------------------------------------------------------------------------- ; Issue 20/12/2007 ; ; This code requires ASM_X86_V1C to be set in aesopt.h. It requires the C files ; aeskey.c and aestab.c for support. ; ; Adapted for TrueCrypt: ; - Compatibility with NASM and GCC ; ; An AES implementation for x86 processors using the YASM (or NASM) assembler. ; This is an assembler implementation that covers encryption and decryption ; only and is intended as a replacement of the C file aescrypt.c. It hence ; requires the file aeskey.c for keying and aestab.c for the AES tables. It ; employs full tables rather than compressed tables. ; This code provides the standard AES block size (128 bits, 16 bytes) and the ; three standard AES key sizes (128, 192 and 256 bits). It has the same call ; interface as my C implementation. The ebx, esi, edi and ebp registers are ; preserved across calls but eax, ecx and edx and the artihmetic status flags ; are not. It is also important that the defines below match those used in the ; C code. This code uses the VC++ register saving conentions; if it is used ; with another compiler, conventions for using and saving registers may need to ; be checked (and calling conventions). The YASM command line for the VC++ ; custom build step is: ; ; yasm -Xvc -f win32 -o "$(TargetDir)\$(InputName).obj" "$(InputPath)" ; ; The calling intefaces are: ; ; AES_RETURN aes_encrypt(const unsigned char in_blk[], ; unsigned char out_blk[], const aes_encrypt_ctx cx[1]); ; ; AES_RETURN aes_decrypt(const unsigned char in_blk[], ; unsigned char out_blk[], const aes_decrypt_ctx cx[1]); ; ; AES_RETURN aes_encrypt_key(const unsigned char key[], ; const aes_encrypt_ctx cx[1]); ; ; AES_RETURN aes_decrypt_key(const unsigned char key[], ; const aes_decrypt_ctx cx[1]); ; ; AES_RETURN aes_encrypt_key(const unsigned char key[], ; unsigned int len, const aes_decrypt_ctx cx[1]); ; ; AES_RETURN aes_decrypt_key(const unsigned char key[], ; unsigned int len, const aes_decrypt_ctx cx[1]); ; ; where is 128, 102 or 256. In the last two calls the length can be in ; either bits or bytes. ; ; Comment in/out the following lines to obtain the desired subroutines. These ; selections MUST match those in the C header file aes.h ; %define AES_128 ; define if AES with 128 bit keys is needed ; %define AES_192 ; define if AES with 192 bit keys is needed %define AES_256 ; define if AES with 256 bit keys is needed ; %define AES_VAR ; define if a variable key size is needed %define ENCRYPTION ; define if encryption is needed %define DECRYPTION ; define if decryption is needed %define AES_REV_DKS ; define if key decryption schedule is reversed %define LAST_ROUND_TABLES ; define if tables are to be used for last round ; offsets to parameters in_blk equ 4 ; input byte array address parameter out_blk equ 8 ; output byte array address parameter ctx equ 12 ; AES context structure stk_spc equ 20 ; stack space %define parms 12 ; parameter space on stack ; The encryption key schedule has the following in memory layout where N is the ; number of rounds (10, 12 or 14): ; ; lo: | input key (round 0) | ; each round is four 32-bit words ; | encryption round 1 | ; | encryption round 2 | ; .... ; | encryption round N-1 | ; hi: | encryption round N | ; ; The decryption key schedule is normally set up so that it has the same ; layout as above by actually reversing the order of the encryption key ; schedule in memory (this happens when AES_REV_DKS is set): ; ; lo: | decryption round 0 | = | encryption round N | ; | decryption round 1 | = INV_MIX_COL[ | encryption round N-1 | ] ; | decryption round 2 | = INV_MIX_COL[ | encryption round N-2 | ] ; .... .... ; | decryption round N-1 | = INV_MIX_COL[ | encryption round 1 | ] ; hi: | decryption round N | = | input key (round 0) | ; ; with rounds except the first and last modified using inv_mix_column() ; But if AES_REV_DKS is NOT set the order of keys is left as it is for ; encryption so that it has to be accessed in reverse when used for ; decryption (although the inverse mix column modifications are done) ; ; lo: | decryption round 0 | = | input key (round 0) | ; | decryption round 1 | = INV_MIX_COL[ | encryption round 1 | ] ; | decryption round 2 | = INV_MIX_COL[ | encryption round 2 | ] ; .... .... ; | decryption round N-1 | = INV_MIX_COL[ | encryption round N-1 | ] ; hi: | decryption round N | = | encryption round N | ; ; This layout is faster when the assembler key scheduling provided here ; is used. ; ; The DLL interface must use the _stdcall convention in which the number ; of bytes of parameter space is added after an @ to the sutine's name. ; We must also remove our parameters from the stack before return (see ; the do_exit macro). Define DLL_EXPORT for the Dynamic Link Library version. ;%define DLL_EXPORT ; End of user defines %ifdef AES_VAR %ifndef AES_128 %define AES_128 %endif %ifndef AES_192 %define AES_192 %endif %ifndef AES_256 %define AES_256 %endif %endif %ifdef AES_VAR %define KS_LENGTH 60 %elifdef AES_256 %define KS_LENGTH 60 %elifdef AES_192 %define KS_LENGTH 52 %else %define KS_LENGTH 44 %endif ; These macros implement stack based local variables %macro save 2 mov [esp+4*%1],%2 %endmacro %macro restore 2 mov %1,[esp+4*%2] %endmacro ; the DLL has to implement the _stdcall calling interface on return ; In this case we have to take our parameters (3 4-byte pointers) ; off the stack %macro do_name 1-2 parms %ifndef DLL_EXPORT align 32 global %1 %1: %else align 32 global %1@%2 export _%1@%2 %1@%2: %endif %endmacro %macro do_call 1-2 parms %ifndef DLL_EXPORT call %1 add esp,%2 %else call %1@%2 %endif %endmacro %macro do_exit 0-1 parms %ifdef DLL_EXPORT ret %1 %else ret %endif %endmacro %ifdef ENCRYPTION extern t_fn %define etab_0(x) [t_fn+4*x] %define etab_1(x) [t_fn+1024+4*x] %define etab_2(x) [t_fn+2048+4*x] %define etab_3(x) [t_fn+3072+4*x] %ifdef LAST_ROUND_TABLES extern t_fl %define eltab_0(x) [t_fl+4*x] %define eltab_1(x) [t_fl+1024+4*x] %define eltab_2(x) [t_fl+2048+4*x] %define eltab_3(x) [t_fl+3072+4*x] %else %define etab_b(x) byte [t_fn+3072+4*x] %endif ; ROUND FUNCTION. Build column[2] on ESI and column[3] on EDI that have the ; round keys pre-loaded. Build column[0] in EBP and column[1] in EBX. ; ; Input: ; ; EAX column[0] ; EBX column[1] ; ECX column[2] ; EDX column[3] ; ESI column key[round][2] ; EDI column key[round][3] ; EBP scratch ; ; Output: ; ; EBP column[0] unkeyed ; EBX column[1] unkeyed ; ESI column[2] keyed ; EDI column[3] keyed ; EAX scratch ; ECX scratch ; EDX scratch %macro rnd_fun 2 rol ebx,16 %1 esi, cl, 0, ebp %1 esi, dh, 1, ebp %1 esi, bh, 3, ebp %1 edi, dl, 0, ebp %1 edi, ah, 1, ebp %1 edi, bl, 2, ebp %2 ebp, al, 0, ebp shr ebx,16 and eax,0xffff0000 or eax,ebx shr edx,16 %1 ebp, ah, 1, ebx %1 ebp, dh, 3, ebx %2 ebx, dl, 2, ebx %1 ebx, ch, 1, edx %1 ebx, al, 0, edx shr eax,16 shr ecx,16 %1 ebp, cl, 2, edx %1 edi, ch, 3, edx %1 esi, al, 2, edx %1 ebx, ah, 3, edx %endmacro ; Basic MOV and XOR Operations for normal rounds %macro nr_xor 4 movzx %4,%2 xor %1,etab_%3(%4) %endmacro %macro nr_mov 4 movzx %4,%2 mov %1,etab_%3(%4) %endmacro ; Basic MOV and XOR Operations for last round %ifdef LAST_ROUND_TABLES %macro lr_xor 4 movzx %4,%2 xor %1,eltab_%3(%4) %endmacro %macro lr_mov 4 movzx %4,%2 mov %1,eltab_%3(%4) %endmacro %else %macro lr_xor 4 movzx %4,%2 movzx %4,etab_b(%4) %if %3 != 0 shl %4,8*%3 %endif xor %1,%4 %endmacro %macro lr_mov 4 movzx %4,%2 movzx %1,etab_b(%4) %if %3 != 0 shl %1,8*%3 %endif %endmacro %endif %macro enc_round 0 add ebp,16 save 0,ebp mov esi,[ebp+8] mov edi,[ebp+12] rnd_fun nr_xor, nr_mov mov eax,ebp mov ecx,esi mov edx,edi restore ebp,0 xor eax,[ebp] xor ebx,[ebp+4] %endmacro %macro enc_last_round 0 add ebp,16 save 0,ebp mov esi,[ebp+8] mov edi,[ebp+12] rnd_fun lr_xor, lr_mov mov eax,ebp restore ebp,0 xor eax,[ebp] xor ebx,[ebp+4] %endmacro section .text align=32 ; AES Encryption Subroutine do_name aes_encrypt sub esp,stk_spc mov [esp+16],ebp mov [esp+12],ebx mov [esp+ 8],esi mov [esp+ 4],edi mov esi,[esp+in_blk+stk_spc] ; input pointer mov eax,[esi ] mov ebx,[esi+ 4] mov ecx,[esi+ 8] mov edx,[esi+12] mov ebp,[esp+ctx+stk_spc] ; key pointer movzx edi,byte [ebp+4*KS_LENGTH] xor eax,[ebp ] xor ebx,[ebp+ 4] xor ecx,[ebp+ 8] xor edx,[ebp+12] ; determine the number of rounds cmp edi,10*16 je .3 cmp edi,12*16 je .2 cmp edi,14*16 je .1 mov eax,-1 jmp .5 .1: enc_round enc_round .2: enc_round enc_round .3: enc_round enc_round enc_round enc_round enc_round enc_round enc_round enc_round enc_round enc_last_round mov edx,[esp+out_blk+stk_spc] mov [edx],eax mov [edx+4],ebx mov [edx+8],esi mov [edx+12],edi xor eax,eax .5: mov ebp,[esp+16] mov ebx,[esp+12] mov esi,[esp+ 8] mov edi,[esp+ 4] add esp,stk_spc do_exit %endif %ifdef DECRYPTION extern t_in %define dtab_0(x) [t_in+4*x] %define dtab_1(x) [t_in+1024+4*x] %define dtab_2(x) [t_in+2048+4*x] %define dtab_3(x) [t_in+3072+4*x] %ifdef LAST_ROUND_TABLES extern t_il %define dltab_0(x) [t_il+4*x] %define dltab_1(x) [t_il+1024+4*x] %define dltab_2(x) [t_il+2048+4*x] %define dltab_3(x) [t_il+3072+4*x] %else extern _t_ibox %define dtab_x(x) byte [_t_ibox+x] %endif %macro irn_fun 2 rol eax,16 %1 esi, cl, 0, ebp %1 esi, bh, 1, ebp %1 esi, al, 2, ebp %1 edi, dl, 0, ebp %1 edi, ch, 1, ebp %1 edi, ah, 3, ebp %2 ebp, bl, 0, ebp shr eax,16 and ebx,0xffff0000 or ebx,eax shr ecx,16 %1 ebp, bh, 1, eax %1 ebp, ch, 3, eax %2 eax, cl, 2, ecx %1 eax, bl, 0, ecx %1 eax, dh, 1, ecx shr ebx,16 shr edx,16 %1 esi, dh, 3, ecx %1 ebp, dl, 2, ecx %1 eax, bh, 3, ecx %1 edi, bl, 2, ecx %endmacro ; Basic MOV and XOR Operations for normal rounds %macro ni_xor 4 movzx %4,%2 xor %1,dtab_%3(%4) %endmacro %macro ni_mov 4 movzx %4,%2 mov %1,dtab_%3(%4) %endmacro ; Basic MOV and XOR Operations for last round %ifdef LAST_ROUND_TABLES %macro li_xor 4 movzx %4,%2 xor %1,dltab_%3(%4) %endmacro %macro li_mov 4 movzx %4,%2 mov %1,dltab_%3(%4) %endmacro %else %macro li_xor 4 movzx %4,%2 movzx %4,dtab_x(%4) %if %3 != 0 shl %4,8*%3 %endif xor %1,%4 %endmacro %macro li_mov 4 movzx %4,%2 movzx %1,dtab_x(%4) %if %3 != 0 shl %1,8*%3 %endif %endmacro %endif %macro dec_round 0 %ifdef AES_REV_DKS add ebp,16 %else sub ebp,16 %endif save 0,ebp mov esi,[ebp+8] mov edi,[ebp+12] irn_fun ni_xor, ni_mov mov ebx,ebp mov ecx,esi mov edx,edi restore ebp,0 xor eax,[ebp] xor ebx,[ebp+4] %endmacro %macro dec_last_round 0 %ifdef AES_REV_DKS add ebp,16 %else sub ebp,16 %endif save 0,ebp mov esi,[ebp+8] mov edi,[ebp+12] irn_fun li_xor, li_mov mov ebx,ebp restore ebp,0 xor eax,[ebp] xor ebx,[ebp+4] %endmacro section .text ; AES Decryption Subroutine do_name aes_decrypt sub esp,stk_spc mov [esp+16],ebp mov [esp+12],ebx mov [esp+ 8],esi mov [esp+ 4],edi ; input four columns and xor in first round key mov esi,[esp+in_blk+stk_spc] ; input pointer mov eax,[esi ] mov ebx,[esi+ 4] mov ecx,[esi+ 8] mov edx,[esi+12] lea esi,[esi+16] mov ebp,[esp+ctx+stk_spc] ; key pointer movzx edi,byte[ebp+4*KS_LENGTH] %ifndef AES_REV_DKS ; if decryption key schedule is not reversed lea ebp,[ebp+edi] ; we have to access it from the top down %endif xor eax,[ebp ] ; key schedule xor ebx,[ebp+ 4] xor ecx,[ebp+ 8] xor edx,[ebp+12] ; determine the number of rounds cmp edi,10*16 je .3 cmp edi,12*16 je .2 cmp edi,14*16 je .1 mov eax,-1 jmp .5 .1: dec_round dec_round .2: dec_round dec_round .3: dec_round dec_round dec_round dec_round dec_round dec_round dec_round dec_round dec_round dec_last_round ; move final values to the output array. mov ebp,[esp+out_blk+stk_spc] mov [ebp],eax mov [ebp+4],ebx mov [ebp+8],esi mov [ebp+12],edi xor eax,eax .5: mov ebp,[esp+16] mov ebx,[esp+12] mov esi,[esp+ 8] mov edi,[esp+ 4] add esp,stk_spc do_exit %endif 386'>386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425