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  1. JDK
  2. JDK-8256556

LDAP Channel Binding support for Java GSS/Kerberos



    • Type: CSR
    • Status: Closed
    • Priority: P3
    • Resolution: Approved
    • Fix Version/s: 13-pool
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • Compatibility Kind:
    • Compatibility Risk:
    • Compatibility Risk Description:
      No compatibility risk.
      This feature adds new environment property to enable LDAP Channel Binding
      No compatibility risk. This feature adds new environment property to enable LDAP Channel Binding
    • Interface Kind:
    • Scope:



      Add support for LDAP Channel Binding information for Java GSS/Kerberos connection. No changes from JDK 16, CSR JDK-8247311


      Microsoft introduced a 'LdapEnforceChannelBinding' option requiring clients to provide channel binding information in order to connect to AD over SSL/TLS.


      The current JDK implementation does not send required Channel Binding data to the server. As a result, LDAPS connection from an authenticated client that uses GSS fails.


      1. Add "com.sun.jndi.ldap.tls.cbtype" JNDI environment property indicating Channel Binding type required for connection. Possible value is:
        • "tls-server-end-point" - Channel Binding data on the base of the server TLS certificate.
      2. The following TLS Channel Binding types are specified in RFC-5929 but not supported:
        • "tls-unique" is not supported.
        • "tls-unique-for-telnet" is not applicable for LDAP connection.
      3. The Channel Binding data is created according to the following specifications:
        • RFC-5929 "Channel Bindings for TLS". Section 4 describes the encoding of the TLS Channel Binding data
        • RFC-5056 "On the Use of Channel Bindings to Secure Channels". Section 2.1 describes the prefix encoding for different channel binding types.
        • RFC-4121. Section describes format end encoding of Channel Binding data for GSS/Kerberos
        • "NTLM and Channel Binding Hash" document. This document describes values and encoding of the initiator/acceptor addresses and address type values.
      4. The Windows LDAP server with LdapEnforceChannelBinding=2 uses the tls-server-end-point channel binding (based on the TLS server certificate). The channel binding data is calculated as follows:
        • Implementation calculates a hash of the TLS server certificate. The hash algorithm is selected on the base of the certificate signature algorithm. Also, the implementation should use SHA-256 algorithm, in case of the certificate signature algorithm is SHA1 or MD5 based
        • Implementation adds name of the Channel Binding type and colon (ASCII 0x3A) before the hash.
        • Initiator and acceptor addresses should be set to NULL
        • Initiator and acceptor address types should be zero. It contradicts the "Using Channel Bindings in GSS-API" document that says that the address type should be set to GSS_C_AF_NULLADDR=0xFF, instead of GSS_C_AF_UNSPEC=0x00. The implementation ensures that the changes in address type are applied to the TLS Channel Binding data only requested by "com.sun.jndi.ldap.tls.cbtype" property.

      Links to the documents:


      Add the following section into src/java.naming/share/classes/module-info.java

      *     <li>{@code com.sun.jndi.ldap.tls.cbtype}:
      *         <br>The value of this property is the string representing the TLS
      *         Channel Binding type required for an LDAP connection over SSL/TLS.
      *         Possible value is :
      *         <ul>
      *             <li>"tls-server-end-point" - Channel Binding data is created on
      *                 the basis of the TLS server certificate.
      *             </li>
      *         </ul>
      *         <br>"tls-unique" TLS Channel Binding type is specified in RFC-5929
      *         but not supported.
      *         <br>If this property is not specified, the client does not send
      *         channel binding information to the server.
      *     </li>


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              abakhtin Alexey Bakhtin
              abakhtin Alexey Bakhtin
              Reviewed By:
              Joe Darcy
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