; Copyright 2015 Egor Tensin ; This file is licensed under the terms of the MIT License. ; See LICENSE.txt for details. .586 .xmm .model flat .data align 10h key_schedule oword 15 dup(0) align 10h inverse_key_schedule oword 15 dup(0) .code @raw_aes256ecb_encrypt@48 proc call expand_keys_256ecb pxor xmm0, [key_schedule] aesenc xmm0, [key_schedule + 10h] aesenc xmm0, [key_schedule + 20h] aesenc xmm0, [key_schedule + 30h] aesenc xmm0, [key_schedule + 40h] aesenc xmm0, [key_schedule + 50h] aesenc xmm0, [key_schedule + 60h] aesenc xmm0, [key_schedule + 70h] aesenc xmm0, [key_schedule + 80h] aesenc xmm0, [key_schedule + 90h] aesenc xmm0, [key_schedule + 0A0h] aesenc xmm0, [key_schedule + 0B0h] aesenc xmm0, [key_schedule + 0C0h] aesenc xmm0, [key_schedule + 0D0h] aesenclast xmm0, [key_schedule + 0E0h] ret @raw_aes256ecb_encrypt@48 endp expand_keys_256ecb proc ; A "word" (in terms of the FIPS 187 standard) is a 32-bit block. ; Words are denoted by `w[N]`. ; ; A key schedule is composed of 14 "regular" keys and a dumb key for ; the "whitening" step. ; It's stored in `key_schedule`. ; ; A key schedule is thus composed of 60 "words". ; The FIPS standard includes an algorithm to calculate these words via ; a simple loop: ; ; i = 8 ; while i < 60: ; temp = w[i - 1] ; if i % 8 == 0: ; temp = SubWord(RotWord(temp))^Rcon ; elif i % 8 == 4: ; temp = SubWord(temp) ; w[i] = w[i - 8]^temp ; i = i + 1 ; ; The loop above may be unrolled like this: ; ; w[8] = SubWord(RotWord(w[7]))^Rcon^w[0] ; w[9] = w[8]^w[1] ; = SubWord(RotWord(w[7]))^Rcon^w[1]^w[0] ; w[10] = w[9]^w[2] ; = SubWord(RotWord(w[7]))^Rcon^w[2]^w[1]^w[0] ; w[11] = w[10]^w[3] ; = SubWord(RotWord(w[7]))^Rcon^w[3]^w[2]^w[1]^w[0] ; w[12] = SubWord(w[11])^w[4] ; w[13] = w[12]^w[5] ; = SubWord(w[11])^w[5]^w[4] ; w[14] = w[13]^w[6] ; = SubWord(w[11])^w[6]^w[5]^w[4] ; w[15] = w[14]^w[7] ; = SubWord(w[11])^w[7]^w[6]^w[5]^w[4] ; w[16] = SubWord(RotWord(w[15]))^Rcon^w[8] ; w[17] = w[16]^w[9] ; = SubWord(RotWord(w[15]))^Rcon^w[9]^w[8] ; w[18] = w[17]^w[10] ; = SubWord(RotWord(w[15]))^Rcon^w[10]^w[9]^w[8] ; w[19] = w[18]^w[11] ; = SubWord(RotWord(w[15]))^Rcon^w[11]^w[10]^w[9]^w[8] ; w[20] = SubWord(w[19])^w[12] ; w[21] = w[20]^w[13] ; = SubWord(w[19])^w[13]^w[12] ; w[22] = w[21]^w[14] ; = SubWord(w[19])^w[14]^w[13]^w[12] ; w[23] = w[22]^w[15] ; = SubWord(w[19])^w[15]^w[14]^w[13]^w[12] ; ; ... and so on. ; ; The Intel AES-NI instruction set facilitates calculating SubWord ; and RotWord using `aeskeygenassist`, which is used in this routine. ; ; Preconditions: ; * xmm2[127:96] == w[7], ; * xmm2[95:64] == w[6], ; * xmm2[63:32] == w[5], ; * xmm2[31:0] == w[4], ; * xmm1[127:96] == w[3], ; * xmm1[95:64] == w[2], ; * xmm1[63:32] == w[1], ; * xmm1[31:0] == w[0]. movdqa [key_schedule], xmm1 ; sets w[0], w[1], w[2], w[3] movdqa [key_schedule + 10h], xmm2 ; sets w[4], w[5], w[6], w[7] lea edx, [key_schedule + 20h] ; ecx = &w[8] aeskeygenassist xmm7, xmm2, 1h ; xmm7[127:96] = RotWord(SubWord(w[7]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[8], w[9], w[10], w[11] aeskeygenassist xmm7, xmm2, 0 ; xmm7[95:64] = SubWord(w[11]) pshufd xmm7, xmm7, 0AAh ; xmm7[127:96] = xmm7[63:32] = xmm7[31:0] = xmm7[95:64] call gen_round_key ; sets w[12], w[13], w[14], w[15] aeskeygenassist xmm7, xmm2, 2h ; xmm7[127:96] = RotWord(SubWord(w[15]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[16], w[17], w[18], w[19] aeskeygenassist xmm7, xmm2, 0 ; xmm7[95:64] = SubWord(w[19]) pshufd xmm7, xmm7, 0AAh ; xmm7[127:96] = xmm7[63:32] = xmm7[31:0] = xmm7[95:64] call gen_round_key ; sets w[20], w[21], w[22], w[23] aeskeygenassist xmm7, xmm2, 4h ; xmm7[127:96] = RotWord(SubWord(w[23]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[24], w[25], w[26], w[27] aeskeygenassist xmm7, xmm2, 0 ; xmm7[95:64] = SubWord(w[27]) pshufd xmm7, xmm7, 0AAh ; xmm7[127:96] = xmm7[63:32] = xmm7[31:0] = xmm7[95:64] call gen_round_key ; sets w[28], w[29], w[30], w[31] aeskeygenassist xmm7, xmm2, 8h ; xmm7[127:96] = RotWord(SubWord(w[31]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[32], w[33], w[34], w[35] aeskeygenassist xmm7, xmm2, 0 ; xmm7[95:64] = SubWord(w[35]) pshufd xmm7, xmm7, 0AAh ; xmm7[127:96] = xmm7[63:32] = xmm7[31:0] = xmm7[95:64] call gen_round_key ; sets w[36], w[37], w[38], w[39] aeskeygenassist xmm7, xmm2, 10h ; xmm7[127:96] = RotWord(SubWord(w[39]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[40], w[41], w[42], w[43] aeskeygenassist xmm7, xmm2, 0 ; xmm7[95:64] = SubWord(w[43]) pshufd xmm7, xmm7, 0AAh ; xmm7[127:96] = xmm7[63:32] = xmm7[31:0] = xmm7[95:64] call gen_round_key ; sets w[44], w[45], w[46], w[47] aeskeygenassist xmm7, xmm2, 20h ; xmm7[127:96] = RotWord(SubWord(w[47]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[48], w[49], w[50], w[51] aeskeygenassist xmm7, xmm2, 0 ; xmm7[95:64] = SubWord(w[51]) pshufd xmm7, xmm7, 0AAh ; xmm7[127:96] = xmm7[63:32] = xmm7[31:0] = xmm7[95:64] call gen_round_key ; sets w[52], w[53], w[54], w[55] aeskeygenassist xmm7, xmm2, 40h ; xmm7[127:96] = RotWord(SubWord(w[55]))^Rcon pshufd xmm7, xmm7, 0FFh ; xmm7[95:64] = xmm7[63:32] = xmm7[31:0] = xmm7[127:96] call gen_round_key ; sets w[56], w[57], w[58], w[59] call invert_key_schedule ret gen_round_key: ; Preconditions: ; * xmm2[127:96] == w[i+7], ; * xmm2[95:64] == w[i+6], ; * xmm2[63:32] == w[i+5], ; * xmm2[31:0] == w[i+4], ; * xmm1[127:96] == w[i+3], ; * xmm1[95:64] == w[i+2], ; * xmm1[63:32] == w[i+1], ; * xmm1[31:0] == w[i], ; * xmm7[127:96] == xmm7[95:64] == xmm7[63:32] == xmm7[31:0] == HWGEN, ; where HWGEN is either RotWord(SubWord(w[i+7]))^Rcon or SubWord(w[i+7]), ; depending on the number of the round being processed, ; * ecx == &w[i+8]. ; ; Postconditions: ; * xmm2[127:96] == w[i+11] == HWGEN^w[i+3]^w[i+2]^w[i+1]^w[i], ; * xmm2[95:64] == w[i+10] == HWGEN^w[i+2]^w[i+1]^w[i], ; * xmm2[63:32] == w[i+9] == HWGEN^w[i+1]^w[i], ; * xmm2[31:0] == w[i+8] == HWGEN^w[i], ; * xmm1[127:96] == w[i+7], ; * xmm1[95:64] == w[i+6], ; * xmm1[63:32] == w[i+5], ; * xmm1[31:0] == w[i+4], ; * ecx == &w[i+12], ; * the value in xmm6 is also modified. ; Calculate ; w[i+3]^w[i+2]^w[i+1]^w[i], ; w[i+2]^w[i+1]^w[i], ; w[i+1]^w[i] and ; w[i]. movdqa xmm6, xmm1 ; xmm6 = xmm1 pslldq xmm6, 4 ; xmm6 <<= 32 pxor xmm1, xmm6 ; xmm1 ^= xmm6 pslldq xmm6, 4 ; xmm6 <<= 32 pxor xmm1, xmm6 ; xmm1 ^= xmm6 pslldq xmm6, 4 ; xmm6 <<= 32 pxor xmm1, xmm6 ; xmm1 ^= xmm6 ; xmm1[127:96] == w[i+3]^w[i+2]^w[i+1]^w[i] ; xmm1[95:64] == w[i+2]^w[i+1]^w[i] ; xmm1[63:32] == w[i+1]^w[i] ; xmm1[31:0] == w[i] ; Calculate ; HWGEN^w[i+3]^w[i+2]^w[i+1]^w[i], ; HWGEN^w[i+2]^w[i+1]^w[i], ; HWGEN^w[i+1]^w[i] and ; HWGEN^w[i]. pxor xmm1, xmm7 ; xmm1 ^= xmm7 ; xmm1[127:96] == w[i+11] == HWGEN^w[i+3]^w[i+2]^w[i+1]^w[i] ; xmm1[95:64] == w[i+10] == HWGEN^w[i+2]^w[i+1]^w[i] ; xmm1[63:32] == w[i+9] == HWGEN^w[i+1]^w[i] ; xmm1[31:0] == w[i+8] == HWGEN^w[i] ; Set w[i+8], w[i+9], w[i+10] and w[i+11]. movdqa [edx], xmm1 ; w[i+8] = HWGEN^w[i] ; w[i+9] = HWGEN^w[i+1]^w[i] ; w[i+10] = HWGEN^w[i+2]^w[i+1]^w[i] ; w[i+11] = HWGEN^w[i+3]^w[i+2]^w[i+1]^w[i] add edx, 10h ; ecx = &w[i+12] ; Swap the values in xmm1 and xmm2. pxor xmm1, xmm2 pxor xmm2, xmm1 pxor xmm1, xmm2 ret invert_key_schedule: movdqa xmm7, [key_schedule ] movdqa xmm6, [key_schedule + 0E0h] movdqa [inverse_key_schedule ], xmm6 movdqa [inverse_key_schedule + 0E0h], xmm7 aesimc xmm7, [key_schedule + 10h] aesimc xmm6, [key_schedule + 0D0h] movdqa [inverse_key_schedule + 10h], xmm6 movdqa [inverse_key_schedule + 0D0h], xmm7 aesimc xmm7, [key_schedule + 20h] aesimc xmm6, [key_schedule + 0C0h] movdqa [inverse_key_schedule + 20h], xmm6 movdqa [inverse_key_schedule + 0C0h], xmm7 aesimc xmm7, [key_schedule + 30h] aesimc xmm6, [key_schedule + 0B0h] movdqa [inverse_key_schedule + 30h], xmm6 movdqa [inverse_key_schedule + 0B0h], xmm7 aesimc xmm7, [key_schedule + 40h] aesimc xmm6, [key_schedule + 0A0h] movdqa [inverse_key_schedule + 40h], xmm6 movdqa [inverse_key_schedule + 0A0h], xmm7 aesimc xmm7, [key_schedule + 50h] aesimc xmm6, [key_schedule + 90h] movdqa [inverse_key_schedule + 50h], xmm6 movdqa [inverse_key_schedule + 90h], xmm7 aesimc xmm7, [key_schedule + 60h] aesimc xmm6, [key_schedule + 80h] movdqa [inverse_key_schedule + 60h], xmm6 movdqa [inverse_key_schedule + 80h], xmm7 aesimc xmm7, [key_schedule + 70h] movdqa [inverse_key_schedule + 70h], xmm7 ret expand_keys_256ecb endp @raw_aes256ecb_decrypt@48 proc call expand_keys_256ecb pxor xmm0, [inverse_key_schedule] aesdec xmm0, [inverse_key_schedule + 10h] aesdec xmm0, [inverse_key_schedule + 20h] aesdec xmm0, [inverse_key_schedule + 30h] aesdec xmm0, [inverse_key_schedule + 40h] aesdec xmm0, [inverse_key_schedule + 50h] aesdec xmm0, [inverse_key_schedule + 60h] aesdec xmm0, [inverse_key_schedule + 70h] aesdec xmm0, [inverse_key_schedule + 80h] aesdec xmm0, [inverse_key_schedule + 90h] aesdec xmm0, [inverse_key_schedule + 0A0h] aesdec xmm0, [inverse_key_schedule + 0B0h] aesdec xmm0, [inverse_key_schedule + 0C0h] aesdec xmm0, [inverse_key_schedule + 0D0h] aesdeclast xmm0, [inverse_key_schedule + 0E0h] ret @raw_aes256ecb_decrypt@48 endp end