Table 2 Evaluation of encryption service in the system

Cryptograhic algorithm: symmetric data encryption

Security function: data encryption

Algorithm-related information:

∙ Initialization vectors (IVs) are used to alleviate the problem of

encrypting the same data with the same key. The problem of

repeated block detection and substitution of individual blocks is

catered by introducing variable IVs.

∙ Shared secrets such as passwords or passphrases can also be used

to generate the key. This key is then used to encrypt the data. For

decryption, the same key needs to be generated via shared secret.

This secret is only shared with the users which are authorized to

access the data.

∙ RNG seeds: random seed values are also used to generate different

keys for the encryption. However, these randomly generated values

are stored at KD service repository in order to get the same key for

decryption.

Cryptoperiods: We define cryptoperiods as the amount of data that are

protected by a given key. For this encryption service, we have used

different keys for each column or table to avoid risks of exposure. Little

data is exposed if key is compromised by any adversary. Moreover,

cryptoperiods to protect the data with one key is usually longer because

of overhead issues of changing keys frequently.

Cryptographic mechanism:

Key size: AES-128

Operating environment: limited access to KDMS service (only to

authorized users)

Protection mechanism:

∙ Availability: backups and replicas of KD service are created at

different locations to make data readily available for cryptographic

functions

∙ Integrity: KD service is protected from unauthorized modifications

using physical and cryptographic mechanisms. This service is placed

at a fully secure environment with appropriate access controls and

limited access. In addition, integrity of the stored information is

checked through message authentication code (MAC).

∙ Confidentiality: an encryption algorithm approved by FIPS 140-2 is

used through which it is not easier to recover the key. Moreover,

controlled access is provided via access control mechanisms.

∙ Integration with other applications: KD service is hosted separately

from other applications and services. This service is organized in a

form of layered architecture and communicates securely via secure

channel; therefore, there are fewer chances of data misuse and

disruption.