fix blum-blum-shub

extra/random/blum-blum-shub/blum-blum-shub-tests.factor

@@ -0,0 +1,28 @@
+USING: kernel math tools.test namespaces random
+random.blum-blum-shub ;
+IN: blum-blum-shub.tests
+
+[ 887708070 ] [
+    T{ blum-blum-shub f 590695557939 811977232793 } random-32*
+] unit-test
+
+
+[ 887708070 ] [
+    T{ blum-blum-shub f 590695557939 811977232793 } [
+        32 random-bits
+    ] with-random
+] unit-test
+
+[ 5726770047455156646 ] [
+    T{ blum-blum-shub f 590695557939 811977232793 } [
+        64 random-bits
+    ] with-random
+] unit-test
+
+[ 3716213681 ]
+[
+    100 T{ blum-blum-shub f 200352954495 846054538649 } tuck [
+        random-32* drop
+    ] curry times
+    random-32*
+] unit-test

extra/random/blum-blum-shub/blum-blum-shub.factor

@@ -3,34 +3,26 @@ math.miller-rabin combinators.lib
 math.functions accessors random ;
 IN: random.blum-blum-shub
 
-! TODO: take (log log M) bits instead of 1 bit
-! Blum Blum Shub, M = pq
+! Blum Blum Shub, n = pq, x_i+1 = x_i ^ 2 mod n
+! return low bit of x+1
 TUPLE: blum-blum-shub x n ;
 
-C: <blum-blum-shub> blum-blum-shub
+<PRIVATE
 
 : generate-bbs-primes ( numbits -- p q )
-    #! two primes congruent to 3 (mod 4)
     [ [ random-prime ] curry [ 4 mod 3 = ] generate ] dup bi ;
 
-IN: crypto
 : <blum-blum-shub> ( numbits -- blum-blum-shub )
-    #! returns a Blum-Blum-Shub tuple
     generate-bbs-primes *
     [ find-relative-prime ] keep
     blum-blum-shub construct-boa ;
 
-! 256 make-bbs blum-blum-shub set-global
-
 : next-bbs-bit ( bbs -- bit )
-    #! x = x^2 mod n, return low bit of calculated x
-    [ [ x>> 2 ] [ n>> ] bi ^mod ]
-    [ [ >>x ] keep x>> 1 bitand ] bi ;
+    [ [ x>> 2 ] [ n>> ] bi ^mod ] keep
+    over >>x drop 1 bitand ;
 
-IN: crypto
-! : random ( n -- n )
-    ! ! #! Cryptographically secure random number using Blum-Blum-Shub 256
-    ! [ log2 1+ random-bits ] keep dupd >= [ -1 shift ] when ;
+PRIVATE>
 
 M: blum-blum-shub random-32* ( bbs -- r )
-    ;
+    0 32 rot
+    [ next-bbs-bit swap 1 shift bitor ] curry times ;