Add length guards

Author: peterdettman

core/src/main/java/org/bouncycastle/math/ec/rfc7748/X25519.java

@@ -53,6 +53,11 @@ private static void decodeScalar(byte[] k, int kOff, int[] n)
 
     public static void generatePrivateKey(SecureRandom random, byte[] k)
     {
+        if (k.length != SCALAR_SIZE)
+        {
+            throw new IllegalArgumentException("k");
+        }
+
         random.nextBytes(k);
 
         k[0] &= 0xF8;

core/src/main/java/org/bouncycastle/math/ec/rfc7748/X448.java

@@ -53,6 +53,11 @@ private static void decodeScalar(byte[] k, int kOff, int[] n)
 
     public static void generatePrivateKey(SecureRandom random, byte[] k)
     {
+        if (k.length != SCALAR_SIZE)
+        {
+            throw new IllegalArgumentException("k");
+        }
+
         random.nextBytes(k);
 
         k[0] &= 0xFC;

core/src/main/java/org/bouncycastle/math/ec/rfc8032/Ed25519.java

@@ -358,6 +358,11 @@ private static int encodePoint(PointAccum p, byte[] r, int rOff)
 
     public static void generatePrivateKey(SecureRandom random, byte[] k)
     {
+        if (k.length != SECRET_KEY_SIZE)
+        {
+            throw new IllegalArgumentException("k");
+        }
+
         random.nextBytes(k);
     }
 

core/src/main/java/org/bouncycastle/math/ec/rfc8032/Ed448.java

@@ -340,6 +340,11 @@ private static int encodePoint(PointProjective p, byte[] r, int rOff)
 
     public static void generatePrivateKey(SecureRandom random, byte[] k)
     {
+        if (k.length != SECRET_KEY_SIZE)
+        {
+            throw new IllegalArgumentException("k");
+        }
+
         random.nextBytes(k);
     }