MessageDigest
is statefull, calls of MessageDigest.update(byte[] input)
accumulate digest updates until we call MessageDigest.digest
. Run this test to make sure:
MessageDigest md1 = MessageDigest.getInstance("MD5");
md1.update(new byte[] {1, 2});
md1.update(new byte[] {3, 4});
System.out.println(Arrays.toString(md1.digest()));
MessageDigest md2 = MessageDigest.getInstance("MD5");
md2.update(new byte[] {1, 2, 3, 4});
System.out.println(Arrays.toString(md2.digest()));
output
[8, -42, -64, 90, 33, 81, 42, 121, -95, -33, -21, -99, 42, -113, 38, 47]
[8, -42, -64, 90, 33, 81, 42, 121, -95, -33, -21, -99, 42, -113, 38, 47]