Column size

  • Hi,

    tried posting this in security thread, but had no luck there, so will try here.

    Hi,

    I have a table to store user sensitive data.

    ...

    CMS_UserName VarChar(25) Unique Not Null Check(SomeChecks)

    ...

    25 characters for the user name is acceptable in my personal opinion.

    I chose to encrypt the data with a symmetric key which is protected by a password.

    25 characters isn't enough to store the encrypted data. I have randomly increased it to 250 and it worked.

    Fact that it works isn't good enough for me and I would like to find out if there is a simple way to determine require column length without doing too much analysis?

    Encryption algorithm used is AES_128, not sure if this is of any help.

    Thank you.

  • Here's something I found when I searched for AES-128 data size

    "AES turns 16 byte input blocks into 16 byte output blocks. The only expansion is to round the data up to a whole number of blocks"

    You should be able to get by with far less than 250 characters for the column width.

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