diff options
Diffstat (limited to 'core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/RandUtils.java')
-rw-r--r-- | core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/RandUtils.java | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/RandUtils.java b/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/RandUtils.java new file mode 100644 index 00000000..dbb1d4a8 --- /dev/null +++ b/core/src/main/java/org/bouncycastle/pqc/math/linearalgebra/RandUtils.java @@ -0,0 +1,25 @@ +package org.bouncycastle.pqc.math.linearalgebra; + +import java.security.SecureRandom; + +public class RandUtils +{ + static int nextInt(SecureRandom rand, int n) + { + + if ((n & -n) == n) // i.e., n is a power of 2 + { + return (int)((n * (long)(rand.nextInt() >>> 1)) >> 31); + } + + int bits, value; + do + { + bits = rand.nextInt() >>> 1; + value = bits % n; + } + while (bits - value + (n - 1) < 0); + + return value; + } +} |