As there are more possible strings than long values, there are surely two different strings resulting in the same checksum.
Henrik
2010-08-18 09:00:23
+5
A:
+1, Also known as the "pigeonhole principle".
Greg Beech
2010-08-18 09:02:01
Greg, +1 for teaching me a new term (pigeonhole principle).
Patrick
2010-08-18 09:03:22
+1
A:
A checksum can never be waterproof, since it contains less data than the original data of which you are calculating the checksum.
If you want a real waterproof 'checksum', you need to create a second 'instance' of your data and make sure that it contains identically the same data as the original data, although it does not have to be in the same format (can be encryped or compressed).
Patrick
2010-08-18 09:02:40