-USING: kernel math sequences namespaces
-math.miller-rabin combinators.lib
-math.functions accessors random ;
+USING: accessors kernel math math.functions math.primes random ;
IN: random.blum-blum-shub
! Blum Blum Shub, n = pq, x_i+1 = x_i ^ 2 mod n
<PRIVATE
+: generate-bbs-prime ( numbits -- p )
+ dup random-prime dup 4 mod 3 =
+ [ nip ] [ drop generate-bbs-prime ] if ;
+
: generate-bbs-primes ( numbits -- p q )
- [ [ random-prime ] curry [ 4 mod 3 = ] generate ] dup bi ;
+ [ generate-bbs-prime ] [ generate-bbs-prime ] bi ;
+
+: next-bbs-bit ( bbs -- bit )
+ dup [ x>> 2 ] [ n>> ] bi ^mod [ >>x drop ] [ 1 bitand ] bi ;
+
+PRIVATE>
: <blum-blum-shub> ( numbits -- blum-blum-shub )
generate-bbs-primes *
[ find-relative-prime ] keep
blum-blum-shub boa ;
-: next-bbs-bit ( bbs -- bit )
- [ [ x>> 2 ] [ n>> ] bi ^mod ] keep
- over >>x drop 1 bitand ;
-
-PRIVATE>
-
-M: blum-blum-shub random-32* ( bbs -- r )
+M: blum-blum-shub random-32*
0 32 rot
[ next-bbs-bit swap 1 shift bitor ] curry times ;