Clean up and modernize librandom.

 Correct random number generation has historically been
suprisingly painful to achieve. There was no standard,
every system behaved in a subtly different way, and there
were a few userland initiatives to get decent randomness,
all incompatible of course.
 The situation is a bit better now, we're heading towards
some standardization. The arc4random() series of functions
is a good API, and available on a lot of systems -
unfortunately not Linux, but on Linux the new getrandom()
makes using /dev/random obsolete.

 So I removed the old crap in librandom, dropped EGD support,
dropped dynamic backend selection, made a single API series
(random_* instead of goodrandom_* and badrandom_*), added
an arc4random backend and a getrandom backend, and defaulted
to /dev/urandom backed up by SURF in the worst case. This
should be much smaller and logical. However, it's a major
API break, so the skarnet.org stack will be changed to
adapt.

1 files changed, 44 insertions, 0 deletions

diff --git a/src/librandom/random_makeseed.c b/src/librandom/random_makeseed.c
new file mode 100644
index 0000000..909e896
--- /dev/null
+++ b/src/librandom/random_makeseed.c
@@ -0,0 +1,44 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <skalibs/uint32.h>
+#include <skalibs/tai.h>
+#include <skalibs/sha1.h>
+
+/*
+   Writes 160 bytes of crap into s.
+   Certainly not cryptographically secure or 100% unpredictable,
+   but we're only using this to speed up /dev/urandom
+   initialization or to init an internal SURF PRNG. 
+   iow: we are CS iff the system's RNG is CS.
+*/
+
+void random_makeseed (char *s)
+{
+  SHA1Schedule bak = SHA1_INIT() ;
+  {
+    tain_t now ;
+    char tmp[256] ;
+    uint32 x = getpid() ;
+    uint32_pack(tmp, x) ;
+    x = getppid() ;
+    uint32_pack(tmp + 4, x) ;
+    tain_now(&now) ;
+    tain_pack(tmp + 8, &now) ;
+    sha1_update(&bak, tmp, 8 + TAIN_PACK) ;
+    gethostname(tmp, 256) ;
+    sha1_update(&bak, tmp, 256) ;
+    sha1_final(&bak, tmp) ;
+    sha1_init(&bak) ;
+    sha1_update(&bak, tmp, 20) ;
+  }  
+  {
+    char i = 0 ;
+    for (; i < 8 ; i++)
+    {
+      SHA1Schedule ctx = bak ;
+      sha1_update(&ctx, &i, 1) ;
+      sha1_final(&ctx, s + 20*i) ;
+    }
+  }
+}