17 Jun
1993
17 Jun
'93
9:13 p.m.
Usually the limiting factor is examining the <ostensibly> decrypted data for statistically significant patterns indicating that you have the correct key.
If you know that your plaintext is 7-bit ASCII, then you can reject if you see too many 8th bits set. [ ... ] Hint for implementors: don't allow such easy bit correlations in your plaintext.
Run your plaintext through compress first; remove the compress header; then encrypt. Compression will screw up character frequencies (and use all eight bits) enough to make automated detection of a successfully-broken encryption really darn hard. Especially if you keep changing compression technology each message. Jazz