[Security] Use a CSPRNG for salts, tokens, and RNG seeding (#7192)

* [Security] Use a CSPRNG for salts, tokens, and RNG seeding

Password salts and activation tokens were generated with the global SFMT
RNG, which was seeded from a 32-bit timestamp, making registration
salts and activation tokens predictable. The game RNG used the same
timestamp seed across restarts.

Add CryptoUtil backed by OpenSSL RAND_bytes and use it for salt/token
generation and to seed RNG_SFMT with a 64-bit CSPRNG value in both the
client and server. Link libcockatrice_utility against OpenSSL::Crypto.

Took 30 seconds

Took 25 minutes

* Lint.

Took 4 minutes

Took 36 seconds

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_rng/libcockatrice/rng/rng_sfmt.cpp

@@ -1,6 +1,5 @@
 #include "rng_sfmt.h"
 
-#include <QDateTime>
 #include <algorithm>
 #include <climits>
 #include <stdexcept>
@@ -11,10 +10,11 @@
 #define UINT64_MAX (~(uint64_t)0)
 #endif
 
-RNG_SFMT::RNG_SFMT(QObject *parent) : RNG_Abstract(parent)
+RNG_SFMT::RNG_SFMT(uint64_t seed, QObject *parent) : RNG_Abstract(parent)
 {
-    // initialize the random number generator with a 32bit integer seed (timestamp)
-    sfmt_init_gen_rand(&sfmt, QDateTime::currentDateTime().toSecsSinceEpoch());
+    // initialize the random number generator with a 64bit seed, e.g. from a CSPRNG
+    uint32_t seedArray[2] = {static_cast<uint32_t>(seed), static_cast<uint32_t>(seed >> 32)};
+    sfmt_init_by_array(&sfmt, seedArray, 2);
 }
 
 /**

libcockatrice_rng/libcockatrice/rng/rng_sfmt.h

@@ -36,7 +36,7 @@ private:
     unsigned int cdf(unsigned int min, unsigned int max);
 
 public:
-    explicit RNG_SFMT(QObject *parent = nullptr);
+    explicit RNG_SFMT(uint64_t seed, QObject *parent = nullptr);
     unsigned int rand(int min, int max) override;
 };