About Password and Key Encryption

CloudStack stores several sensitive passwords and secret keys that are used to provide security. These values are always automatically encrypted:

• Database secret key
• Database password
• SSH keys
• Compute node root password
• VPN password
• User API secret key
• VNC password

CloudStack uses the Java Simplified Encryption (JASYPT) library. The data values are encrypted and decrypted using a database secret key, which is stored in one of CloudStack’s internal properties files along with the database password. The other encrypted values listed above, such as SSH keys, are in the CloudStack internal database.

Of course, the database secret key itself can not be stored in the open – it must be encrypted. How then does CloudStack read it? A second secret key must be provided from an external source during Management Server startup. This key can be provided in one of two ways: loaded from a file or provided by the CloudStack administrator. The CloudStack database has a configuration setting that lets it know which of these methods will be used. If the encryption type is set to “file,” the key must be in a file in a known location. If the encryption type is set to “web,” the administrator runs the utility com.cloud.utils.crypt.EncryptionSecretKeySender, which relays the key to the Management Server over a known port.

The encryption type, database secret key, and Management Server secret key are set during CloudStack installation. They are all parameters to the CloudStack database setup script (cloudstack-setup-databases). The default values are file, password, and password. It is, of course, highly recommended that you change these to more secure keys.

Changing the Default Password Encryption

Passwords are encoded when creating or updating users. CloudStack allows you to determine the default encoding and authentication mechanism for admin and user logins. Two new configurable lists have been introduced—userPasswordEncoders and userAuthenticators. userPasswordEncoders allows you to configure the order of preference for encoding passwords, whereas userAuthenticators allows you to configure the order in which authentication schemes are invoked to validate user passwords.

Additionally, the plain text user authenticator has been modified not to convert supplied passwords to their md5 sums before checking them with the database entries. It performs a simple string comparison between retrieved and supplied login passwords instead of comparing the retrieved md5 hash of the stored password against the supplied md5 hash of the password because clients no longer hash the password. The following method determines what encoding scheme is used to encode the password supplied during user creation or modification.

When a new user is created, the user password is encoded by using the first valid encoder loaded as per the sequence specified in the UserPasswordEncoders property in the ComponentContext.xml or nonossComponentContext.xml files. The order of authentication schemes is determined by the UserAuthenticators property in the same files. If Non-OSS components, such as VMware environments, are to be deployed, modify the UserPasswordEncoders and UserAuthenticators lists in the nonossComponentContext.xml file, for OSS environments, such as XenServer or KVM, modify the ComponentContext.xml file. It is recommended to make uniform changes across both the files. When a new authenticator or encoder is added, you can add them to this list. While doing so, ensure that the new authenticator or encoder is specified as a bean in both these files. The administrator can change the ordering of both these properties as preferred to change the order of schemes. Modify the following list properties available in client/tomcatconf/nonossComponentContext.xml.in or client/tomcatconf/componentContext.xml.in as applicable, to the desired order:

<property name="UserAuthenticators">
   <list>
      <ref bean="SHA256SaltedUserAuthenticator"/>
      <ref bean="MD5UserAuthenticator"/>
      <ref bean="LDAPUserAuthenticator"/>
      <ref bean="PlainTextUserAuthenticator"/>
   </list>
</property>
<property name="UserPasswordEncoders">
   <list>
      <ref bean="SHA256SaltedUserAuthenticator"/>
      <ref bean="MD5UserAuthenticator"/>
      <ref bean="LDAPUserAuthenticator"/>
      <ref bean="PlainTextUserAuthenticator"/>
   </list>
</property>

In the above default ordering, SHA256Salt is used first for UserPasswordEncoders. If the module is found and encoding returns a valid value, the encoded password is stored in the user table’s password column. If it fails for any reason, the MD5UserAuthenticator will be tried next, and the order continues. For UserAuthenticators, SHA256Salt authentication is tried first. If it succeeds, the user is logged into the Management server. If it fails, md5 is tried next, and attempts continues until any of them succeeds and the user logs in . If none of them works, the user is returned an invalid credential message.