Blocksize versus file size was: Re: twofish keysize

[Per Tunedal Casual]

At 16:26 2004-04-20, C. D. Rok wrote:
 >Per Tunedal Casual wrote:
 >
 >> BTW I've been told it isn't wise to encrypt files larger than a few MB
 >> using a block size of 64 bits.
 >
 >I wasn't aware of this; is it cipher dependent od does it apply to
 >all block ciphers? Any pointers to additinal info?
 >
 >TIA,
 >C. Rok
 >
It appears to apply to all block ciphers, but it should be "a few HUNDRED 
megabytes", according to what I found with Google:

"Blowfish has a 64 bit block size and a key length of anywhere from 32 bits 
to 448 bits. ... It should be noted that, like other block cyphers with a 
64 bit block, it is risky to encrypt extremely large texts (more than a few 
hundred megabytes) with a single key. If more data is to be encrypted a 
block cipher with a larger block size should be used."
(http://www.djhd.com/onlinehelp/ac/encryption_overview.htm)

Per Tunedal