To Pool or not to Pool java crypto service providers

Question

Solution

• MessageDigest => create new instances as often as needed
• KeyFactory => use a single shared instance
• SecureRandom => use a StackObject

Answer 1

This test seems to be in favour of caching

long t0 = System.currentTimeMillis();
byte[] bytes = new byte[100];
MessageDigest md = MessageDigest.getInstance("MD5");
for(int i = 0; i < 1000000; i++) {
    //MessageDigest md = MessageDigest.getInstance("MD5");
    md.reset();
    md.update(bytes);
    md.digest();
}
System.out.println(System.currentTimeMillis() - t0);

When md is outside the loop it prints 579, when inside - 953.