Database encryption improves data security. However, it does have disadvantages. For a start, encrypted data needs to be decrypted when accessed in order for it to be useful. Therefore, the decryption process slows down access to data. Encrypting the data for storage also slows down the data input phase. There is going to be a point that data extracted from the database will be in a plain text format. This is a point of weakness, particularly with database systems that cache results in memory for rapid, repeated access – this stores the data in an unencrypted format. Another problem is the issue of encryption keys. If the same key is used for the entire database, renewing that key would require all of the database’s contents to be decrypted and re-encrypted, which is a time-consuming task. If the encryption is not periodically renewed, there is a risk that the key could be discovered and all security compromised.