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-rw-r--r--src/aes256ecb.asm259
1 files changed, 188 insertions, 71 deletions
diff --git a/src/aes256ecb.asm b/src/aes256ecb.asm
index f67f4bd..68430a1 100644
--- a/src/aes256ecb.asm
+++ b/src/aes256ecb.asm
@@ -37,83 +37,200 @@ inverse_key_schedule oword 15 dup(0)
@raw_aes256ecb_encrypt@48 endp
expand_keys_256ecb proc
- lea edx, [key_schedule + 20h]
- movdqa [key_schedule], xmm1
- movdqa [key_schedule + 10h], xmm2
-
- aeskeygenassist xmm7, xmm2, 1h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 0
- pshufd xmm7, xmm7, 0AAh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 2h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 0
- pshufd xmm7, xmm7, 0AAh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 4h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 0
- pshufd xmm7, xmm7, 0AAh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 8h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 0
- pshufd xmm7, xmm7, 0AAh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 10h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 0
- pshufd xmm7, xmm7, 0AAh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 20h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 0
- pshufd xmm7, xmm7, 0AAh
- call gen_round_key
-
- aeskeygenassist xmm7, xmm2, 40h
- pshufd xmm7, xmm7, 0FFh
- call gen_round_key
+ ; 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:
- movdqa xmm6, xmm1
-
- pslldq xmm6, 4
- pxor xmm1, xmm6
- pslldq xmm6, 4
- pxor xmm1, xmm6
- pslldq xmm6, 4
- pxor xmm1, xmm6
-
- pxor xmm1, xmm7
-
- movdqa [edx], xmm1
- add edx, 10h
+ ; 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
- movdqa xmm7, xmm1
- movdqa xmm1, xmm2
- movdqa xmm2, xmm7
ret
invert_key_schedule:
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-23 22:50:05 +0000