Passwords are a central aspect of any security system. This section describes how GeoServer handles passwords.
A GeoServer configuration stores two types of passwords:
- Passwords for user accounts to access GeoServer resources
- Passwords used internally for accessing external services such as databases and cascading OGC services
As these passwords are typically stored on disk it is strongly recommended that they be encrypted and not stored as human-readable text. GeoServer security provides four schemes for encrypting passwords: empty, plain text, Digest, and Password-based encryption (PBE).
The password encryption scheme is specified as a global setting that affects the encryption of passwords used for external resources, and as an encryption scheme for each user/group service. The encryption scheme for external resources has to be be reversible, while the user/group services can use any scheme.
The scheme is not reversible. Any password is encoded as an empty string, and as a consequence it is not possible to recalculate the plain text password. This scheme is used for user/group services in combination with an authentication mechanism using a back end system. Examples are user name/password authentication against a LDAP server or a JDBC database. In these scenarios, storing passwords locally to Geoserver does not make sense.
Prior to version 2.2.0, plain text encryption was the only available method used by GeoServer for storing passwords.
Plain text passwords provide no encryption at all. In this case, passwords are human-readable by anyone who has access to the file system. For obvious reasons, this is not recommended for any but the most basic test server. A password mypassword is encoded as plain:mypassword, the prefix uniquely describing the algorithm used for encoding/decoding.
Digest encryption is not reversible. It applies, 100,000 times through an iterative process, a SHA-256 cryptographic hash function to passwords. This scheme is “one-way” in that it is virtually impossible to reverse and obtain the original password from its hashed representation. Please see the section on Reversible encryption for more information on reversibility.
To protect from well known attacks, a random value called a salt is added to the password when generating the key. For each digesting, a separate random salt is used. Digesting the same password twice results in different hashed representations.
As an example, the password geoserver is digested to digest1:YgaweuS60t+mJNobGlf9hzUC6g7gGTtPEu0TlnUxFlv0fYtBuTsQDzZcBM4AfZHd. digest1 indicates the usage of digesting. The hashed representation and the salt are base 64 encoded.
Password-based encryption (PBE) normally employs a user-supplied password to generate an encryption key. This scheme is reversible. A random salt described in the previous section is used.
The system never uses passwords specified by users because these passwords tend to be weak. Passwords used for encryption are generated using a secure random generator and stored in the GeoServer key store. The number of possible passwords is 2^260 .
GeoServer supports two forms of PBE. Weak PBE (the GeoServer default) uses a basic encryption method that is relatively easy to crack. The encryption key is derived from the password using MD5 1000 times iteratively. The encryption algorithm itself is DES (Data Encryption Standard). DES has an effective key length of 56 bits, which is not really a challenge for computer systems in these days.
Strong PBE uses a much stronger encryption method based on an AES 256-bit algorithm with CBC. The key length is 256 bit and is derived using SHA-256 instead of MD5. Using Strong PBE is highly recommended.
As an example, the password geoserver is encrypted to crypt1:KWhO7jrTz/Gi0oTQRKsVeCmWIZY5VZaD. crypt1 indicates the usage of Weak PBE. The prefix for Strong PBE is crypt2. The ciphertext and the salt are base 64 encoded.
Strong PBE is not natively available on all Java virtual machines and may require Installing Unlimited Strength Jurisdiction Policy Files
Password encryption methods can be reversible, meaning that it is possible (and desirable) to obtain the plain-text password from its encrypted version. Reversible passwords are necessary for database connections or external OGC services such as cascading WMS and cascading WFS, since GeoServer must be able to decode the encrypted password and pass it to the external service. Plain text and PBE passwords are reversible.
Non-reversible passwords provide the highest level of security, and therefore should be used for user accounts and wherever else possible. Using password digesting is highly recommended, the installation of the unrestricted policy files is not required.
Secret keys and the keystore¶
For a reversible password to provide a meaningful level of security, access to the password must be restricted in some way. In GeoServer, encrypting and decrypting passwords involves the generation of secret shared keys, stored in a typical Java keystore. GeoServer uses its own keystore for this purpose named geoserver.jceks which is located in the security directory in the GeoServer data directory. This file is stored in the JCEKS format rather than the default JKS. JKS does not support storing shared keys.
The GeoServer keystore is password protected with a Master password. It is possible to access the contents of the keystore with external tools such as keytool. For example, this following command would prompt for the master password and list the contents of the keystore:
$ keytools -list -keystore geoserver.jceks -storetype "JCEKS"
It is also possible to set a master password for GeoServer. This password serves two purposes:
By default, the master password is generated and stored in a file named security/masterpw.info using plain text. When upgrading from an existing GeoServer data directory (versions 2.1.x and lower), the algorithm attempts to figure out the password of a user with the role ROLE_ADMINISTRATOR. If such a password is found and the password length is 8 characters at minimum, GeoServer uses this password as master password. Again, the name of the chosen user is found in security/masterpw.info.
The file security/masterpw.info is a security risk. The administrator should read this file and verify the master password by logging on GeoServer as the root user. On success, this file should be removed.
Refer to Active master password provider for information on how to change the master password.
A password policy defines constraints on passwords such as password length, case, and required mix of character classes. Password policies are specified when adding User/group services and are used to constrain passwords when creating new users and when changing passwords of existing users.
Each user/group service uses a password policy to enforce these rules. The default GeoServer password policy implementation supports the following optional constraints:
- Passwords must contain at least one number
- Passwords must contain at least one upper case letter
- Passwords must contain at least one lower case letter
- Password minimum length
- Password maximum length