This section describes security features regarding Java Generic Security Services (Java GSS) for Kerberos 5.
The GSS-API mechanism is defined by RFC 1964, supplemented with RFC 4121 under the Official Internet Protocol Standards process. See RFC 1964 and RFC 4121.
This section also describes the Object Identifier (OID) for the Kerberos V5 mechanism, in the Official Internet Protocol Standards process, the encryption types, and the krb5.conf settings supported by Java GSS.
According to RFC 1964 section 1, the OID for Java Generic Security Services (Java GSS) for Kerberos 5 is defined as 1.2.840.113554.1.2.
The following table lists the preferred order of encryption types:
| Name | Aliases | etype Number |
|---|---|---|
| aes256-cts-hmac-sha1-96 | aes256-cts | 18 |
| aes128-cts-hmac-sha1-96 | aes128-cts | 17 |
| arcfour-hmac-md5 | arcfour-hmac | 23 |
| des3-cbc-sha1 | des3-hmac-sha1, des3-cbc-sha1-kd, des3-cbc-hmac-sha1-kd | 16 |
| des-cbc-md5 | None | 3 |
| des-cbc-crc | None | 1 |
Note that des-cbc-crc and dec-cbc-md5 are disabled by default in JDK 8.
A user can restrict the usage of encryption for various purposes in krb5.conf, in the [libdefaults] section.
For more detailed information about the AES encryption types (AES128 and AES256) and the RC4-HMAC encryption type, see Java Generic Security Services API and Kerberos Enhancements for Java SE 6.
For more detailed information about the DES and Triple DES encryption types, see Java Generic Security Services API and Kerberos Enhancements for Java SE 5.0 and Support for Triple DES Encryption.
The following parameters are supported:
[libdefaults]
default_realm
allow_weak_crypto
dns_lookup_kdc
dns_lookup_realm
dns_fallback
default_checksum
safe_checksum_type
ap_req_checksum_type
default_keytab_name
default_tkt_enctypes
permitted_enctypes
default_tgs_enctypes
no_addresses
noaddresses
renewable
proxiable
forwardable
kdc_default_options
clockskew
kdc_timeout
udp_preference_limit
[realms]
REALM.NAME = {
kdc =
}
[capaths]
A = {
I = .
B = I
}
[domain_realm]
domain=REALM
The following are the defaults for the krb5.conf file parameters.
no_addresses = true noaddresses = true dns_fallback = true dns_lookup_kdc = true dns_lookup_realm = true allow_weak_crypto = false kdc_timeout = 30000 max_retries = 3 udp_preference_limit = -1 clockskew = 300 renewable = false proxiable = false forwardable = false
