IT27021: .NET client application connecting with elliptical curve cipherSuite fails with MQRC_Q_MGR_NOT_AVAILABLE

APAR status

• Closed as program error.

Error description

• When an MQ client application specifies a long name for an
  elliptic curve (ECC) CipherSpec, such as:
    TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384_P384
  
  This value is truncated to one that does not exist, such as:
    TLS_ECDHE_ECDSA_WITH_AES_256_GCM
  
  Client application reports MQRC_Q_MGR_NOT_AVAILABLE
  18:14:50.603251  :   {
  MQEncryptedSocket.MakeSecuredConnection()
  18:14:50.606793  :   Starting SSL Authentication
  18:14:50.777172  :   Exception received
  IBM.WMQ.Nmqi.NmqiException
  Message: MQRC_Q_MGR_NOT_AVAILABLE
  
  QM error log reports AMQ9631 error
  
  18:14:50.794140  1033203.1193412      :            RetCode =
  20009631,
  rc1 = 0, rc2 = 0, Comment1 = 'MQ.QUEUE    ', Comment2 =
  'ECDHE_ECDSA_AES_256_GCM_SHA384  ', Comment3=
  'TLS_RSA_WITH_AES_128_CBC_SHA
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of MQ .NET applications in managed mode connecting with an
  SSL Channel and using a CipherSpec with a name longer than 32
  characters.
  
  
  Platforms affected:
  Windows
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  Due to a coding error, a 32-character buffer was used internally
  within the MQ.NET code to record the CipherSpec to use. This
  meant that CipherSpecs with longer names were truncated.
  
  In the provided example, the MQ managed .NET client code was
  truncating the elliptic curve CipherSpec, which caused the .NET
  client to propose the default protocol level of either SSL3.0 or
  TLS 1.0 to the server during the handshake. The server was
  configured to reject this proposal.
  

Problem conclusion

• The MQ managed .NET client code has been corrected such that it
  is able to internally use elliptic curve CipherSpec definitions
  which are greater than 32 characters long, so that correct
  SSL/TLS protocol version will be proposed to the server by the
  client.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.0 LTS   9.0.0.7
  v9.1 CD    9.1.3
  v9.1 LTS   9.1.0.3
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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:

Fix information

• Fixed component name

  IBM MQ BASE M/P

• Fixed component ID

  5724H7261

Applicable component levels