Create and store a segment of random data equal in size to the data being encrypted.
XOR the user data with stored random data.
Encrypt both the random segment and the user data with conventional block cipher methods.
Since the user data was XORed with randomness, reminiscent of OTP. This would prevent usage of a precomputed dictionary against known plain text.
Obviously, users of this solution double their storage requirements.
Attachment:
signature.asc
Description: OpenPGP digital signature