OA55141: SIGNING CERTIFICATE NOT ALLOWED TO SIGN OCSP RESPONSE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• An SSL trace is showing System SSL performing a
  check_ocsp_signer_extensions and the response is 'signing
  certificate not allowed to sign OCSP response.
  The OCSP signer certificate fulfills RFC3280 and has two
  extensions:
   keyUsage (critical) : nonRepudiation
   extendedKeyUsage: ocspSigning
  
  RFC3280 and RFC5280 say:
  If a certificate contains both a key usage extension and an
  extended key usage extension, then both extensions MUST be
  processed independently and the certificate MUST only be used
  for a purpose consistent with both extensions.  If there is no
  purpose consistent with both extensions, then the certificate
  MUST NOT be used for any purpose.
  
   id-kp-OCSPSigning            OBJECT IDENTIFIER ::= { id-kp 9 >
  
      -- Signing OCSP responses
      -- Key usage bits that may be consistent: digitalSignature
      -- and/or nonRepudiation
  
  From the description of the OCSPSigning OID in the RFC  that by
  not including non-Reprudiation in our check for the key usage
  extension we are not allowing those certificates to Sign
  OCSP Responses
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Users of z/OS System SSL using OCSP                          *
  * revocation support                                           *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * When verifying an OCSP response                              *
  * signature, System SSL checks that the                        *
  * OCSP signing certificate has the                             *
  * authority to sign an OCSP response. If                       *
  * the OCSP signing certificate contains                        *
  * a key usage extension, the System SSL                        *
  * code was only checking for the crlSign                       *
  * and digitalSignature bits.                                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * APPLY PTF                                                    *
  ****************************************************************
  According to RFCs 3280 and 5280, System SSL should also include
  a check for the nonrepudiation bit when the OCSP signing
  certificate contains a key usage extension.
  

Problem conclusion

• If the OCSP signing certificate contains a key usage extension,
  System SSL will now check if the crlSign, digitalSignature, or
  the nonrepudiation bits are set. (The check for the
  nonrepudiation bit being set in the key usage extension is new).
  If any of these bits are set in the key usage extension, System
  SSL will now allow the OCSP response signature to be verified.
  
  This APAR support has been provided through internal defect
  ZD0085Y0.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UA96149 UA96150 UA96158 UA96159 UA96160

Modules/Macros

• GSKC31F  GSKC31   GSKCMS31 GSKCMS64 GSKC64   GSKC64F
  

Fix information

• Fixed component name

  SYSTEM SSL

• Fixed component ID

  565506805

Applicable component levels

• R420 PSY UA96159

     UP18/05/11 P F805

• R421 PSY UA96160

     UP18/05/15 P F805

• R431 PSY UA96158

     UP18/05/11 P F805

• R430 PSY UA96149

     UP18/05/11 P F805

Fix is available

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