Database Encryption
Came across this while google-surfing:
<quote>
Disk space is an issue with database encryption because encrypted fields
are larger than unencrypted fields. They're a little larger for textual
data and a lot larger for numeric and binary data--data in a numeric field,
for example, gets encrypted one byte at a time and grows to two bytes when it's encrypted. [...]
Most database-encryption mechanisms present encrypted data as characters, one character per hexadecimal digit. That's a big increase: When encrypted, a 4-byte integer becomes an 8-byte character string. Most encryption algorithms use 64-bit DES, so your 4-byte (32-bit) integer becomes a string of 16 encrypted characters.
</quote>
The mind boggles.
SQLcrypt operates at the storage layer and cares not whether the data is textual or numeric at the SQL layer. One byte of plain text <=> one byte of cipher text.
Do you have the URL for that quote? For most block cipher, the cipher text should be the same size as the clear text, even if the encryption is done at the record level. And that applies to DES as well.
It makes more sense to say that plain text would use more storage space as the cipher text does not compress well. But I guess does not apply in your case where for SQLcrypt encryption is done at the storage level.
Google for it - I think you will find several pieces purportedly by different authors expressing similar sentiments.
A block cipher that pads will add bytes if the plaintext is not of the exact size.
(Tauto what? Me? Nah... ;-)
[link deleted]
ngps: I left the link on for a while, since it was on topic for this post, but the entire presentation of this thing - nothing but links, one of which pointed to your corporate site home page - smacked of spamming to me, so I've zapped the links.
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