Avoid creating and discarding java.util.SecureRandom repeatedly

[fvasco]

Creating a SecureRandom instance may involve a blocking operation. At the same time, SecureRandom is thread-safe, so it's recommended to create a static instance and reuse it multiple times.

Finally, please consider that (int) max can be a negative number (ie: (int) Long.MAX_VALUE).

See:

altcha-lib-java/src/main/java/org/altcha/altcha/Altcha.java

Line 228 in ddb1826

new SecureRandom().nextBytes(bytes);

altcha-lib-java/src/main/java/org/altcha/altcha/Altcha.java

Line 249 in ddb1826

SecureRandom random = new SecureRandom();

altcha-lib-java/src/main/java/org/altcha/altcha/Altcha.java

Line 250 in ddb1826

return random.nextInt((int) max);