SECURING FIBRE CHANNEL FABRICS - Brocade

Chapter 4: Security Basics for Storage ProfessionalsPurgingData purging is used to protect against sophisticated laboratoryattacks using specialized equipment such as electron microscopesand sophisticated diagnostic and forensic tools. Degaussing, passinga magnetic field through a magnetic media, is an acceptable methodof purging data, although certain types of degaussers are more effectivethan others depending on their energy rating. Clearly degaussingwill not work on non-magnetic media such as optical media.DestructionPhysical destruction of the media is the only accepted method to completelyprevent the recovery of data on magnetic media; once themedia has been destroyed it can no longer be reused. Physicaldestruction can be accomplished by disintegrating, incinerating, pulverizing,shredding, and melting. These methods are usually reservedfor the most sensitive data and are the most common methods usedby military and intelligence agencies to destroy media containing confidentialdata. They are also often used in combination with each other,for example, a disk may be first crushed then incinerated or melted.Data sanitization procedures should also include verification processesto ensure proper confidentiality is maintained. Randomsamples of sanitized media should be tested by persons not involvedin the actual sanitization process.Electronic Data Shredding MethodsSeveral methods and algorithms have been developed to electronicallyshred data. Some of these algorithms are standards used by militaryand other government agencies for clearing certain types of data.Some algorithms may only be used to shred non-classified or non-sensitivedata, while others are acceptable for confidential or top secretdata. Commonly used data cleaning algorithms are listed in Table 8.Table 2. Data cleaning algorithmsAlgorithm Passes DescriptionUS Army 3 Pass 1- random bytes; passes 2 and 3with certain bytes and with itscomplimentUS DoD 5220.22-M 3 Pass 1– zeroes; pass 2 – ones; pass 3 –random bytesUS Navy NAVSOP-5239-263 Overwriting with pass verification70 Securing Fibre Channel Fabrics