406 lines
9.0 KiB
Perl
406 lines
9.0 KiB
Perl
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# Copyright (c) 2018, Amazon Inc.
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#
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# Permission to use, copy, modify, and/or distribute this software for any
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# purpose with or without fee is hereby granted, provided that the above
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# copyright notice and this permission notice appear in all copies.
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#
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# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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# SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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# OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#
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# Written by Nir Drucker, and Shay Gueron
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# AWS Cryptographic Algorithms Group
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# (ndrucker@amazon.com, gueron@amazon.com)
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# based on BN_mod_inverse_odd
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$flavour = shift;
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$output = shift;
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if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }
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$win64=0; $win64=1 if ($flavour =~ /[nm]asm|mingw64/ || $output =~ /\.asm$/);
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$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
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( $xlate="${dir}x86_64-xlate.pl" and -f $xlate ) or
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( $xlate="${dir}../../../perlasm/x86_64-xlate.pl" and -f $xlate) or
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die "can't locate x86_64-xlate.pl";
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open OUT,"| \"$^X\" \"$xlate\" $flavour \"$output\"";
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*STDOUT=*OUT;
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#############################################################################
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# extern int beeu_mod_inverse_vartime(BN_ULONG out[P256_LIMBS],
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# BN_ULONG a[P256_LIMBS],
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# BN_ULONG n[P256_LIMBS]);
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#
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# (Binary Extended Euclidean Algorithm.
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# See https://en.wikipedia.org/wiki/Binary_GCD_algorithm)
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#
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# Assumption 1: n is odd for the BEEU
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# Assumption 2: 1 < a < n < 2^256
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$out = "%rdi";
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$a = "%rsi";
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$n = "%rdx";
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# X/Y will hold the inverse parameter
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# Assumption: X,Y<2^(256)
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$x0 = "%r8";
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$x1 = "%r9";
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$x2 = "%r10";
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$x3 = "%r11";
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# borrow from out (out is needed only at the end)
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$x4 = "%rdi";
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$y0 = "%r12";
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$y1 = "%r13";
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$y2 = "%r14";
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$y3 = "%r15";
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$y4 = "%rbp";
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$shift = "%rcx";
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$t0 = "%rax";
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$t1 = "%rbx";
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$t2 = "%rsi";
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# borrow
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$t3 = "%rcx";
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$T0 = "%xmm0";
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$T1 = "%xmm1";
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# Offsets on the stack
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$out_rsp = 0;
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$shift_rsp = $out_rsp+0x8;
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$a_rsp0 = $shift_rsp+0x8;
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$a_rsp1 = $a_rsp0+0x8;
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$a_rsp2 = $a_rsp1+0x8;
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$a_rsp3 = $a_rsp2+0x8;
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$b_rsp0 = $a_rsp3+0x8;
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$b_rsp1 = $b_rsp0+0x8;
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$b_rsp2 = $b_rsp1+0x8;
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$b_rsp3 = $b_rsp2+0x8;
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# Borrow when a_rsp/b_rsp are no longer needed.
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$y_rsp0 = $a_rsp0;
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$y_rsp1 = $y_rsp0+0x8;
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$y_rsp2 = $y_rsp1+0x8;
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$y_rsp3 = $y_rsp2+0x8;
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$y_rsp4 = $y_rsp3+0x8;
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$last_rsp_offset = $b_rsp3+0x8;
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sub TEST_B_ZERO {
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return <<___;
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xorq $t1, $t1
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or $b_rsp0(%rsp), $t1
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or $b_rsp1(%rsp), $t1
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or $b_rsp2(%rsp), $t1
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or $b_rsp3(%rsp), $t1
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jz .Lbeeu_loop_end
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___
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}
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$g_next_label = 0;
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sub SHIFT1 {
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my ($var0, $var1, $var2, $var3, $var4) = @_;
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my $label = ".Lshift1_${g_next_label}";
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$g_next_label++;
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return <<___;
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# Ensure X is even and divide by two.
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movq \$1, $t1
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andq $var0, $t1
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jz $label
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add 0*8($n), $var0
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adc 1*8($n), $var1
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adc 2*8($n), $var2
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adc 3*8($n), $var3
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adc \$0, $var4
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$label:
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shrdq \$1, $var1, $var0
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shrdq \$1, $var2, $var1
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shrdq \$1, $var3, $var2
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shrdq \$1, $var4, $var3
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shrq \$1, $var4
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___
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}
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sub SHIFT256 {
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my ($var) = @_;
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return <<___;
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# Copy shifted values.
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# Remember not to override t3=rcx
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movq 1*8+$var(%rsp), $t0
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movq 2*8+$var(%rsp), $t1
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movq 3*8+$var(%rsp), $t2
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shrdq %cl, $t0, 0*8+$var(%rsp)
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shrdq %cl, $t1, 1*8+$var(%rsp)
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shrdq %cl, $t2, 2*8+$var(%rsp)
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shrq %cl, $t2
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mov $t2, 3*8+$var(%rsp)
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___
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}
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$code.=<<___;
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.text
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.type beeu_mod_inverse_vartime,\@function
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.hidden beeu_mod_inverse_vartime
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.globl beeu_mod_inverse_vartime
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.align 32
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beeu_mod_inverse_vartime:
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.cfi_startproc
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push %rbp
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.cfi_push rbp
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movq %rsp, %rbp
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.cfi_def_cfa_register rbp
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push %r12
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.cfi_push r12
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push %r13
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.cfi_push r13
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push %r14
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.cfi_push r14
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push %r15
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.cfi_push r15
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push %rbx
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.cfi_push rbx
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push %rsi
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.cfi_push rsi
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sub \$$last_rsp_offset, %rsp
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movq $out, $out_rsp(%rsp)
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# X=1, Y=0
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movq \$1, $x0
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xorq $x1, $x1
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xorq $x2, $x2
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xorq $x3, $x3
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xorq $x4, $x4
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xorq $y0, $y0
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xorq $y1, $y1
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xorq $y2, $y2
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xorq $y3, $y3
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xorq $y4, $y4
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# Copy a/n into B/A on the stack.
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vmovdqu 0*8($a), $T0
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vmovdqu 2*8($a), $T1
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vmovdqu $T0, $b_rsp0(%rsp)
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vmovdqu $T1, $b_rsp2(%rsp)
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vmovdqu 0*8($n), $T0
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vmovdqu 2*8($n), $T1
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vmovdqu $T0, $a_rsp0(%rsp)
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vmovdqu $T1, $a_rsp2(%rsp)
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.Lbeeu_loop:
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${\TEST_B_ZERO}
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# 0 < B < |n|,
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# 0 < A <= |n|,
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# (1) X*a == B (mod |n|),
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# (2) (-1)*Y*a == A (mod |n|)
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# Now divide B by the maximum possible power of two in the
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# integers, and divide X by the same value mod |n|. When we're
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# done, (1) still holds.
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movq \$1, $shift
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# Note that B > 0
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.Lbeeu_shift_loop_XB:
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movq $shift, $t1
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andq $b_rsp0(%rsp), $t1
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jnz .Lbeeu_shift_loop_end_XB
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${\SHIFT1($x0, $x1, $x2, $x3, $x4)}
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shl \$1, $shift
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# Test wraparound of the shift parameter. The probability to have 32 zeroes
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# in a row is small Therefore having the value below equal \$0x8000000 or
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# \$0x8000 does not affect the performance. We choose 0x8000000 because it
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# is the maximal immediate value possible.
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cmp \$0x8000000, $shift
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jne .Lbeeu_shift_loop_XB
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.Lbeeu_shift_loop_end_XB:
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bsf $shift, $shift
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test $shift, $shift
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jz .Lbeeu_no_shift_XB
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${\SHIFT256($b_rsp0)}
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.Lbeeu_no_shift_XB:
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# Same for A and Y. Afterwards, (2) still holds.
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movq \$1, $shift
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# Note that A > 0
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.Lbeeu_shift_loop_YA:
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movq $shift, $t1
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andq $a_rsp0(%rsp), $t1
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jnz .Lbeeu_shift_loop_end_YA
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${\SHIFT1($y0, $y1, $y2, $y3, $y4)}
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shl \$1, $shift
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# Test wraparound of the shift parameter. The probability to have 32 zeroes
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# in a row is small therefore having the value below equal \$0x8000000 or
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# \$0x8000 Does not affect the performance. We choose 0x8000000 because it
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# is the maximal immediate value possible.
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cmp \$0x8000000, $shift
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jne .Lbeeu_shift_loop_YA
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.Lbeeu_shift_loop_end_YA:
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bsf $shift, $shift
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test $shift, $shift
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jz .Lbeeu_no_shift_YA
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${\SHIFT256($a_rsp0)}
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.Lbeeu_no_shift_YA:
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# T = B-A (A,B < 2^256)
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mov $b_rsp0(%rsp), $t0
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mov $b_rsp1(%rsp), $t1
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mov $b_rsp2(%rsp), $t2
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mov $b_rsp3(%rsp), $t3
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sub $a_rsp0(%rsp), $t0
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sbb $a_rsp1(%rsp), $t1
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sbb $a_rsp2(%rsp), $t2
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sbb $a_rsp3(%rsp), $t3 # borrow from shift
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jnc .Lbeeu_B_bigger_than_A
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# A = A - B
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mov $a_rsp0(%rsp), $t0
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mov $a_rsp1(%rsp), $t1
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mov $a_rsp2(%rsp), $t2
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mov $a_rsp3(%rsp), $t3
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sub $b_rsp0(%rsp), $t0
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sbb $b_rsp1(%rsp), $t1
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sbb $b_rsp2(%rsp), $t2
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sbb $b_rsp3(%rsp), $t3
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mov $t0, $a_rsp0(%rsp)
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mov $t1, $a_rsp1(%rsp)
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mov $t2, $a_rsp2(%rsp)
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mov $t3, $a_rsp3(%rsp)
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# Y = Y + X
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add $x0, $y0
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adc $x1, $y1
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adc $x2, $y2
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adc $x3, $y3
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adc $x4, $y4
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jmp .Lbeeu_loop
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.Lbeeu_B_bigger_than_A:
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# B = T = B - A
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mov $t0, $b_rsp0(%rsp)
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mov $t1, $b_rsp1(%rsp)
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mov $t2, $b_rsp2(%rsp)
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mov $t3, $b_rsp3(%rsp)
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# X = Y + X
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add $y0, $x0
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adc $y1, $x1
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adc $y2, $x2
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adc $y3, $x3
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adc $y4, $x4
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jmp .Lbeeu_loop
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.Lbeeu_loop_end:
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# The Euclid's algorithm loop ends when A == beeu(a,n);
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# Therefore (-1)*Y*a == A (mod |n|), Y>0
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# Verify that A = 1 ==> (-1)*Y*a = A = 1 (mod |n|)
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mov $a_rsp0(%rsp), $t1
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sub \$1, $t1
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or $a_rsp1(%rsp), $t1
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or $a_rsp2(%rsp), $t1
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or $a_rsp3(%rsp), $t1
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# If not, fail.
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jnz .Lbeeu_err
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# From this point on, we no longer need X
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# Therefore we use it as a temporary storage.
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# X = n
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movq 0*8($n), $x0
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movq 1*8($n), $x1
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movq 2*8($n), $x2
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movq 3*8($n), $x3
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xorq $x4, $x4
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.Lbeeu_reduction_loop:
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movq $y0, $y_rsp0(%rsp)
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movq $y1, $y_rsp1(%rsp)
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movq $y2, $y_rsp2(%rsp)
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movq $y3, $y_rsp3(%rsp)
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movq $y4, $y_rsp4(%rsp)
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# If Y>n ==> Y=Y-n
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sub $x0, $y0
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sbb $x1, $y1
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sbb $x2, $y2
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sbb $x3, $y3
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sbb \$0, $y4
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||
|
|
# Choose old Y or new Y
|
||
|
|
cmovc $y_rsp0(%rsp), $y0
|
||
|
|
cmovc $y_rsp1(%rsp), $y1
|
||
|
|
cmovc $y_rsp2(%rsp), $y2
|
||
|
|
cmovc $y_rsp3(%rsp), $y3
|
||
|
|
jnc .Lbeeu_reduction_loop
|
||
|
|
|
||
|
|
# X = n - Y (n, Y < 2^256), (Cancel the (-1))
|
||
|
|
sub $y0, $x0
|
||
|
|
sbb $y1, $x1
|
||
|
|
sbb $y2, $x2
|
||
|
|
sbb $y3, $x3
|
||
|
|
|
||
|
|
.Lbeeu_save:
|
||
|
|
# Save the inverse(<2^256) to out.
|
||
|
|
mov $out_rsp(%rsp), $out
|
||
|
|
|
||
|
|
movq $x0, 0*8($out)
|
||
|
|
movq $x1, 1*8($out)
|
||
|
|
movq $x2, 2*8($out)
|
||
|
|
movq $x3, 3*8($out)
|
||
|
|
|
||
|
|
# Return 1.
|
||
|
|
movq \$1, %rax
|
||
|
|
jmp .Lbeeu_finish
|
||
|
|
|
||
|
|
.Lbeeu_err:
|
||
|
|
# Return 0.
|
||
|
|
xorq %rax, %rax
|
||
|
|
|
||
|
|
.Lbeeu_finish:
|
||
|
|
add \$$last_rsp_offset, %rsp
|
||
|
|
pop %rsi
|
||
|
|
.cfi_pop rsi
|
||
|
|
pop %rbx
|
||
|
|
.cfi_pop rbx
|
||
|
|
pop %r15
|
||
|
|
.cfi_pop r15
|
||
|
|
pop %r14
|
||
|
|
.cfi_pop r14
|
||
|
|
pop %r13
|
||
|
|
.cfi_pop r13
|
||
|
|
pop %r12
|
||
|
|
.cfi_pop r12
|
||
|
|
pop %rbp
|
||
|
|
.cfi_pop rbp
|
||
|
|
.cfi_def_cfa rsp, 8
|
||
|
|
.cfi_endproc
|
||
|
|
ret
|
||
|
|
|
||
|
|
.size beeu_mod_inverse_vartime, .-beeu_mod_inverse_vartime
|
||
|
|
___
|
||
|
|
|
||
|
|
print $code;
|
||
|
|
close STDOUT;
|