stong

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animetosho

Unexpected Uses for the Galois Field Affine Transformation Instruction

Intel added the Galois Field instruction set (GFNI) extensions to their Sunny Cove and Tremont cores. What’s particularly interesting is that GFNI is the only new SIMD extension that came with SSE and VEX/AVX encodings (in addition to EVEX/AVX512), to allow it to be supported on all future Intel cores, including those which don’t support AVX512 (such as the Atom line, as well as Celeron/Pentium branded “big” cores).

I suspect GFNI was aimed at accelerating SM4 encryption, however, one of the instructions can be used for many other purposes. The extension includes three instructions, but of particular interest here is the Affine Transformation (GF2P8AFFINEQB), aka bit-matrix multiply, instruction.

There have been various articles which discuss out-of-band

pakt

#
# read/write access to python's memory, using a custom bytearray.
# some code taken from: http://tinyurl.com/q7duzxj
#
# tested on:
# Python 2.7.10, ubuntu 32bit
# Python 2.7.8, win32
#
# example of correct output:
# inspecting int=0x41424344, at 0x0228f898

s3rvac

// $ g++ -std=c++14 -pedantic -Wall -Wextra double-dispatch.cpp -o double-dispatch
// $ ./double-dispatch
//
// Also works under C++11.

#include <iostream>
#include <memory>

#if __cplusplus == 201103L
namespace std {

michaljemala

package main

import (
	"crypto/tls"
	"crypto/x509"
	"flag"
	"io/ioutil"
	"log"
	"net/http"
)

sneves

/*
Constant-time integer comparisons
 
Written in 2014 by Samuel Neves <[email protected]>
 
To the extent possible under law, the author(s) have dedicated all copyright
and related and neighboring rights to this software to the public domain
worldwide. This software is distributed without any warranty.
 
You should have received a copy of the CC0 Public Domain Dedication along with

klutzy

extern mod syntax;
extern mod rustc;

pub use syntax::ast;
pub use rustc::middle::ty;
pub use rustc::middle::ty::t;

fn cpp_arg_mangle(arg: t) -> ~str {
    let arg = ty::get(arg);
    match arg.sty {

CodesInChaos

function LoginHash(string password, byte[] salt, int memSize, int queryCount, int maxParallelism)
    return KDF(password, salt, memSize, queryCount, maxParallelism, "LoginVerification", 16) 

function KDF(string password, byte[] salt, int memSize, int queryCount, int maxParallelism, string info, int outputSize)
    masterKey = ComputeMasterKey(password, salt, memSize, queryCount, maxParallelism) 
    return HKDF-Expand(masterKey, info, outputSize) // For short outputs this is simply HMAC-SHA-256(masterKey, info || 0x01).Truncate(outputSize)
 
function ComputeMasterKey(string password, byte[] salt, int memSize, int queryCount, int maxParallelism) 
    requires memSize mod 16 = 0 
    requires memSize > 0