Merge branch 'keccak'

* keccak:
  KECCAK: README.md: extend description
  Makefile: add keccak/
  KECCAK: Makefile: build and run Keccak tests
  KECCAK: main.cc: add benchmark and test cases for Keccak and auto_seed()
  KECCAK: testvectors.c: add all n*8 bit test vectors from ShortMsgKAT_0.txt
  KECCAK: keccak.cc: add KeccakRng::auto_seed() entropy gathering implementation
  KECCAK: keccak.hh: add 1600 bit Keccak sponge PRNG
  KECCAK: README.md: add readme with brief description

Signed-off-by: Tim Janik <timj@gnu.org>

Makefile

@@ -2,7 +2,7 @@
 
 all:		# Default Rule
 
-SUBDIRS	:= chacha shishua
+SUBDIRS	:= keccak chacha shishua
 
 all clean check:
 	 @ true $(foreach DIR, $(SUBDIRS), && $(MAKE) -C "$(DIR)" "$@" )

keccak/Makefile

@@ -0,0 +1,22 @@
+# Dedicated to the Public Domain under the Unlicense: https://unlicense.org/UNLICENSE
+
+all:		# Default Rule
+
+MAYBE_CLANG	!= clang++ --version 2>/dev/null | grep -q 'clang.* [1-9][0-9]\+\.' && echo clang++
+CXX		:= $(if $(MAYBE_CLANG), $(MAYBE_CLANG), $(CXX))
+OPTIMIZE	:= -O3 -march=native
+
+# == keccak ==
+keccak: main.cc Makefile
+	$(CXX) -std=gnu++17 -Wall $(OPTIMIZE) $< -o keccak
+keccak: keccak.hh keccak.cc
+clean: ; rm -f ./keccak
+all: keccak
+
+# == check ==
+check: keccak
+	./keccak --check
+
+# == dieharder ==
+dieharder: keccak
+	./keccak | dieharder -a -g 200

keccak/README.md

@@ -0,0 +1,26 @@
+
+# Keccak PRNG Implementation
+
+The header file `keccak.hh` contains a Keccak sponge construction implementation for generic CPUs (ALU)
+in the `class scl::Keccak::class KeccakRng`. The implementation is are based on the original
+[Specification of Keccak](https://keccak.team/files/Keccak-reference-3.0.pdf) from 2011.
+The header file can be used on its own for cryptographic hashing via Keccak.
+
+However, the method `KeccakRng::auto_seed()` is implemented in the source file `keccak.cc`, it allows
+the use of a `KeccakRng` sponge as an entropy pool for cryptographically secure random seeds for other PRNGs.
+
+The code for `KeccakRng::auto_seed()` gathers entropy from various system sources such as
+`/dev/urandom`, `getrandom(2)`, `getentropy(3)`, `arc4random(3bsd)`, `RDTSC`, `RDRAND` and high precision clocks.
+The code performs detailed timing measurements to improve the quality of the gathered entropy, according to this
+paper from 2013 that deals with entropy gathering in embedded systems at boot time:
+[Welcome to the Entropics: Boot-Time Entropy in Embedded Devices](https://cseweb.ucsd.edu/~swanso/).
+The entropy pool uses `class KeccakRng` with 1600 bits of state, of which 576 are hidden bits,
+to guarantee cryptographically secure mixing.
+
+The source file `main.cc` contains random number generation examples, benchmarks and unit test code based
+on the Keccak test vectors.
+
+The source code is dedicated to the Public Domain under the [Unlicense](https://unlicense.org/UNLICENSE).
+
+
+

keccak/keccak.cc

@@ -0,0 +1,166 @@
+// Dedicated to the Public Domain under the Unlicense: https://unlicense.org/UNLICENSE
+
+// #include "keccak.hh"
+#include <unistd.h>             // getentropy
+#include <sys/random.h>         // getrandom
+#include <stdlib.h>             // arc4random
+#include <sys/time.h>           // gettimeofday
+#include <time.h>               // clock_gettime
+#include <random>               // std::random_device
+#include <chrono>               // std::chrono
+#include <sys/resource.h>       // getrusage
+#if defined (__i386__) || defined (__x86_64__)
+#  include <x86gprintrin.h>     // __rdtsc
+#endif
+
+namespace scl::Keccak {
+
+static void
+seed_addtime (KeccakRng &pool)
+{
+  // Gather entropy from execution time fluctuations, see:
+  // "Welcome to the Entropics: Boot-Time Entropy in Embedded Devices",
+  // https://cseweb.ucsd.edu/~swanson/papers/Oakland2013EarlyEntropy.pdf
+  std::array<uint64_t, 25> xw{};
+#if defined (__i386__) || defined (__x86_64__)
+  xw[0] = __rdtsc();
+#endif
+  xw[1] = std::chrono::steady_clock::now().time_since_epoch().count();
+  xw[2] = std::chrono::system_clock::now().time_since_epoch().count();
+  xw[3] = clock();
+  struct timeval timeval{};
+  gettimeofday (&timeval, nullptr);
+  xw[4] = timeval.tv_sec;
+  xw[5] = timeval.tv_usec;
+  struct timespec ts{};
+  clock_gettime (CLOCK_REALTIME, &ts);
+  xw[6] = ts.tv_sec;
+  xw[7] = ts.tv_nsec;
+  clock_gettime (CLOCK_MONOTONIC, &ts);
+  xw[8] = ts.tv_sec;
+  xw[9] = ts.tv_nsec;
+  clock_gettime (CLOCK_PROCESS_CPUTIME_ID, &ts);
+  xw[10] = ts.tv_sec;
+  xw[11] = ts.tv_nsec;
+#if defined (__i386__) || defined (__x86_64__)
+  xw[12] = __rdtsc();
+#endif
+  pool.update64 (xw.data(), xw.size(), false);
+}
+
+static bool
+seed_addfile (KeccakRng &pool, const char *filename, const size_t maxbytes = 200)
+{
+  FILE *file = fopen (filename, "r");
+  if (file)
+    {
+      std::array<uint8_t, 200> xs{};
+      const size_t l = fread (xs.data(), 1, maxbytes < xs.size() ? maxbytes : xs.size(), file);
+      fclose (file);
+      pool.update (xs.data(), xs.size(), false);
+      seed_addtime (pool); // execution timing
+      return l > 0;
+    }
+  return false;
+}
+
+static void
+random_entropy (KeccakRng &pool)
+{
+  seed_addtime (pool); // execution timing
+
+  std::array<uint64_t, 25> xw{}; // engouh state to feed Keccak1600
+
+  // Peek at C++ random_device
+  if (true) {
+    // std::random_device easily throws for non-default sources
+    // also some impls reopen devices for every 32bit operator() call.
+    std::random_device cpprd;
+    static_assert (sizeof (cpprd()) == 4);
+    xw[0] = cpprd() + (uint64_t (cpprd()) << 32);
+    pool.update64 (xw.data(), xw.size(), false);
+    seed_addtime (pool); // execution timing
+  }
+
+  // HW counter if any
+#if defined(__RDRND__)
+  xw = std::array<uint64_t, 25>{};
+  for (size_t i = 0; i < xw.size(); i++) {
+    unsigned long long ull = 0;
+    __builtin_ia32_rdrand64_step (&ull);
+    xw[i] = ull;
+  }
+  pool.update64 (xw.data(), xw.size(), false);
+  seed_addtime (pool); // execution timing
+#endif
+
+  xw = std::array<uint64_t, 25>{};
+  xw[0] = time (nullptr);
+  xw[1] = getpid();
+  xw[2] = gettid();
+  xw[10] = std::ptrdiff_t (&xw[23]);            // stack/thread location
+  xw[11] = std::ptrdiff_t (&pool);              // instance location
+  xw[12] = std::ptrdiff_t (random_entropy);     // code segment
+  xw[13] = std::ptrdiff_t (&malloc);            // libc segment
+  pool.update64 (xw.data(), xw.size(), false);
+  seed_addtime (pool); // execution timing
+
+  // read from frequently changing files
+  seed_addfile (pool, "/dev/urandom");
+  seed_addfile (pool, "/proc/stat");
+  seed_addfile (pool, "/proc/uptime");
+  seed_addfile (pool, "/proc/loadavg");
+  seed_addfile (pool, "/proc/softirqs");
+  seed_addfile (pool, "/proc/schedstat");
+  seed_addfile (pool, "/proc/diskstats");
+  seed_addfile (pool, "/proc/interrupts");
+  seed_addfile (pool, "/proc/sys/kernel/random/uuid");
+  // seed_addfile (pool, "/proc/vmstat");
+  // seed_addfile (pool, "/proc/meminfo");
+  // seed_addfile (pool, "/proc/zoneinfo");
+
+  std::array<uint8_t, 200> xs{}; // engouh state to feed Keccak1600
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
+  auto const dummy1 [[maybe_unused]] = getrandom (xs.data(), xs.size(), GRND_NONBLOCK);
+  pool.update (xs.data(), xs.size(), false);
+#endif
+
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
+  auto const dummy2 [[maybe_unused]] = getentropy (xs.data(), xs.size());
+  pool.update (xs.data(), xs.size(), false);
+#endif
+
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__DragonFly__)
+  arc4random_buf (xs.data(), xs.size());
+  pool.update (xs.data(), xs.size(), false);
+#endif
+
+  // process statistics
+  union {
+    uint8_t         data[25 * 8];
+    struct {
+      struct rusage rusage;     // 144 bytes
+    } stats;
+    static_assert (sizeof (stats) <= sizeof (data));
+  } u = { { 0 }, };
+  getrusage (RUSAGE_SELF, &u.stats.rusage);
+  pool.update (u.data, sizeof (u.data), false);
+
+  seed_addtime (pool); // execution timing
+}
+
+/** Tap into various OS and runtime sources of entropy.
+ * Gathering entropy from system and runtime sources may take a few microseconds
+ * or milliseconds so it is recommended to call this once and use the KeccakRng
+ * to reseed other PRNGs.
+ */
+void
+KeccakRng::auto_seed()
+{
+  reset();
+  random_entropy (*this);
+  update (nullptr, 0, false); // finalize
+  keccak1600_permute (state_.A, 37);
+}
+
+} // scl::Keccak