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Simpler ChaCha20 vector code

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Frank Denis 2020-10-10 21:12:24 +02:00
parent 459128e059
commit 9f109ba0eb
1 changed files with 18 additions and 33 deletions
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51
lib/std/crypto/chacha20.zig
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@ -34,67 +34,52 @@ const ChaCha20VecImpl = struct {
};
}
inline fn chacha20Core(x: *BlockVec, input: BlockVec) void {
const rot8 = [_]i32{ 3, 0, 1, 2, 7, 4, 5, 6, 11, 8, 9, 10, 15, 12, 13, 14 };
const rot16 = [_]i32{ 2, 3, 0, 1, 6, 7, 4, 5, 10, 11, 8, 9, 14, 15, 12, 13 };
inline fn rot(x: Lane, comptime n: comptime_int) Lane {
return (x << @splat(4, @as(u5, n))) | (x >> @splat(4, @as(u5, 32 - n)));
}
inline fn chacha20Core(x: *BlockVec, input: BlockVec) void {
x.* = input;
var r: usize = 0;
while (r < 20) : (r += 2) {
x[0] +%= x[1];
x[3] ^= x[0];
x[3] = @bitCast(Vector(4, u32), @shuffle(u8, @bitCast(Vector(16, u8), x[3]), undefined, rot16));
x[3] = rot(x[3], 16);
x[2] +%= x[3];
x[1] ^= x[2];
var t1 = x[1];
x[1] <<= @splat(4, @as(u5, 12));
t1 >>= @splat(4, @as(u5, 20));
x[1] ^= t1;
x[1] = rot(x[1], 12);
x[0] +%= x[1];
x[3] ^= x[0];
x[0] = @shuffle(u32, x[0], undefined, Vector(4, i32){ 3, 0, 1, 2 });
x[3] = @bitCast(Vector(4, u32), @shuffle(u8, @bitCast(Vector(16, u8), x[3]), undefined, rot8));
x[0] = @shuffle(u32, x[0], undefined, [_]i32{ 3, 0, 1, 2 });
x[3] = rot(x[3], 8);
x[2] +%= x[3];
x[3] = @shuffle(u32, x[3], undefined, Vector(4, i32){ 2, 3, 0, 1 });
x[3] = @shuffle(u32, x[3], undefined, [_]i32{ 2, 3, 0, 1 });
x[1] ^= x[2];
x[2] = @shuffle(u32, x[2], undefined, Vector(4, i32){ 1, 2, 3, 0 });
t1 = x[1];
x[1] <<= @splat(4, @as(u5, 7));
t1 >>= @splat(4, @as(u5, 25));
x[1] ^= t1;
x[2] = @shuffle(u32, x[2], undefined, [_]i32{ 1, 2, 3, 0 });
x[1] = rot(x[1], 7);
x[0] +%= x[1];
x[3] ^= x[0];
x[3] = @bitCast(Vector(4, u32), @shuffle(u8, @bitCast(Vector(16, u8), x[3]), undefined, rot16));
x[3] = rot(x[3], 16);
x[2] +%= x[3];
x[1] ^= x[2];
t1 = x[1];
x[1] <<= @splat(4, @as(u5, 12));
t1 >>= @splat(4, @as(u5, 20));
x[1] ^= t1;
x[1] = rot(x[1], 12);
x[0] +%= x[1];
x[3] ^= x[0];
x[0] = @shuffle(u32, x[0], undefined, Vector(4, i32){ 1, 2, 3, 0 });
x[3] = @bitCast(Vector(4, u32), @shuffle(u8, @bitCast(Vector(16, u8), x[3]), undefined, rot8));
x[0] = @shuffle(u32, x[0], undefined, [_]i32{ 1, 2, 3, 0 });
x[3] = rot(x[3], 8);
x[2] +%= x[3];
x[3] = @shuffle(u32, x[3], undefined, Vector(4, i32){ 2, 3, 0, 1 });
x[3] = @shuffle(u32, x[3], undefined, [_]i32{ 2, 3, 0, 1 });
x[1] ^= x[2];
x[2] = @shuffle(u32, x[2], undefined, Vector(4, i32){ 3, 0, 1, 2 });
t1 = x[1];
x[1] <<= @splat(4, @as(u5, 7));
t1 >>= @splat(4, @as(u5, 25));
x[1] ^= t1;
x[2] = @shuffle(u32, x[2], undefined, [_]i32{ 3, 0, 1, 2 });
x[1] = rot(x[1], 7);
}
}