From 04d5d6d38f605249105f507fa26715f357e7dd07 Mon Sep 17 00:00:00 2001
From: Malte <malte.flender@fh-bielefeld.de>
Date: Sat, 19 Apr 2014 18:35:51 +0200
Subject: [PATCH] rand:ntru_get_rnd_poly_small: written a function to generate
 a random polynom

like get_urnd_int_small but with the random source from /dev/random
instead of /dev/urandom
---
 src/Makefile |  2 +-
 src/rand.c   | 36 ++++++++++++++++++++++++++++++++++--
 src/rand.h   |  1 +
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/src/Makefile b/src/Makefile
index fd3ce31..95b5320 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -57,7 +57,7 @@ endif
 %.o: %.c
 	$(CC) -fPIC $(CFLAGS) $(CPPFLAGS) $(INCS) -c $*.c
 
-all: libpqc.a libpqc.so main
+all: libpqc.a libpqc.so
 
 
 # test: $(CUNIT_OBJS) $(PQC_LIBS)
diff --git a/src/rand.c b/src/rand.c
index 0f88a85..956d9ad 100644
--- a/src/rand.c
+++ b/src/rand.c
@@ -42,6 +42,7 @@ static mp_digit get_rnd_int_small(int *sign);
 /**
  * Gets randomly a small integer
  * from the set {-1, 0, 1} using /dev/random.
+ * A zero is signed positiv.
  *
  * @param sign stores the signness [out]
  * @return random small integer
@@ -77,9 +78,41 @@ static mp_digit get_rnd_int_small(int *sign)
 	return random_int;
 }
 
+/**
+ * Gets a random polynomial with coefficients
+ * from the set {-1 ,0 ,1} using /dev/random.
+ *
+ *
+ * @param ctx the NTRU context
+ * @return newly allocated polynomial, must be freed with delete_polynom()
+ */
+pb_poly *ntru_get_rnd_poly_small(ntru_context *ctx)
+{
+	mp_int chara;
+	init_integer(&chara);
+	pb_poly *poly = malloc(sizeof(pb_poly));
+	init_polynom_size(poly, &chara, ctx->N);
+	mp_clear(&chara);
+
+	for (int i = 0; i < ctx->N; i++) {
+		int sign;
+		int c = get_rnd_int_small(&sign);
+
+		mp_set(&(poly->terms[i]), (mp_digit) c);
+
+		if (sign == 1)
+			poly->terms[i].sign = 1;
+	}
+	poly->used = ctx->N;
+	//pb_clamp(poly);
+
+	return poly;
+}
+
 /**
  * Gets randomly a small integer
  * from the set {-1, 0, 1} using /dev/urandom.
+ * A zero is signed positiv.
  *
  * @param sign stores the signness [out]
  * @return random small integer
@@ -134,8 +167,7 @@ pb_poly *ntru_get_urnd_poly_small(ntru_context *ctx)
 			poly->terms[i].sign = 1;
 	}
 	poly->used = ctx->N;
-	pb_clamp(poly);
+	//pb_clamp(poly);
 
 	return poly;
 }
-
diff --git a/src/rand.h b/src/rand.h
index adafdf8..6db9c7d 100644
--- a/src/rand.h
+++ b/src/rand.h
@@ -29,5 +29,6 @@
 
 
 pb_poly *ntru_get_urnd_poly_small(ntru_context *ctx);
+pb_poly *ntru_get_rnd_poly_small(ntru_context *ctx);
 
 #endif /* NTRU_RAND_H */