From 56ff4530ff9b34fcc15050fd8af66b71e751b572 Mon Sep 17 00:00:00 2001
From: Doug Coleman <doug.coleman@gmail.com>
Date: Mon, 7 Apr 2008 19:28:54 -0500
Subject: [PATCH] fix blum-blum-shub
---
.../blum-blum-shub-tests.factor | 28 +++++++++++++++++++
.../blum-blum-shub/blum-blum-shub.factor | 24 ++++++----------
2 files changed, 36 insertions(+), 16 deletions(-)
create mode 100644 extra/random/blum-blum-shub/blum-blum-shub-tests.factor
diff --git a/extra/random/blum-blum-shub/blum-blum-shub-tests.factor b/extra/random/blum-blum-shub/blum-blum-shub-tests.factor
new file mode 100644
index 0000000000..a92f256eeb
--- /dev/null
+++ b/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
diff --git a/extra/random/blum-blum-shub/blum-blum-shub.factor b/extra/random/blum-blum-shub/blum-blum-shub.factor
index 017ef402c0..5644cf6d08 100755
--- a/extra/random/blum-blum-shub/blum-blum-shub.factor
+++ b/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 ;