SQL Server 2005 and higher provide a security infrastructure that supports hierarchical encryption and key management.
PowerDesigner supports encryption with certificates and asymmetric and symmetric keys.
Certificates (SQL Server)
A public key certificate, usually just called a certificate, is a digitally-signed statement that binds the value of a public key to the identity of the person, device, or service that holds the corresponding private key. Certificates are issued and signed by a certification authority (CA). The entity that receives a certificate from a CA is the subject of that certificate. PowerDesigner models certificates as extended objects with a stereotype of <<Certificate>>.
Asymmetric Keys (SQL Server)
An asymmetric key is made up of a private key and the corresponding public key. Each key can decrypt data encrypted by the other. Asymmetric encryption and decryption are relatively resource-intensive, but they provide a higher level of security than symmetric encryption. An asymmetric key can be used to encrypt a symmetric key for storage in a database. PowerDesigner models asymmetric keys as extended objects with a stereotype of <<AsymmetricKey>>.
Symmetric Keys (SQL Server)
A symmetric key is one key that is used for both encryption and decryption. Encryption and decryption by using a symmetric key is fast, and suitable for routine use with sensitive data in the database. PowerDesigner models symmetric keys as extended objects with a stereotype of <<SymmetricKey>>.