You wrote:

If the encryption method is any good, the output will be pseudo-random with no digit being more frequent than any other. This certainly applies to IDEA and DES. With RSA, you usually have a random (IDEA) session key encrypted using the senders private key. This will also be an effectively 'random' number.

Just a technical note, but a normal distribution of digits (i.e. 'no digit more frequent than any other') is no inidication of either randomness or 'good' encryption. A better test is to look for a normal distribution at all scale levels. For example, the following text block: "UUU" (in ASCII) has a normal distribution at the bit level "0101 0101 0101 0101 0101 0101", but not at the byte level. Dale H.