IV64490: BIGINTEGER.MODINVERSE RETURNS BIGINTEGER OBJECTS WITH NON-CANONI CAL INTERNAL REPRESENTATION

APAR status

• Closed as program error.

Error description

• Error Message: When creating BigInteger with modInverse, the
  internal representation is not the same with the ones when
  creating with constructors. When the modPow method is JITted,
  the calculations go wrong.
  .
  Stack Trace: N/A
  .
  N/A
  

Local fix

• Construct another BigInteger object with the returned value from
  BigInteger.modInvers() and use it to call BigInteger.modPow().
  

Problem summary

• There are two problems caused by the non-canonical internal
  representation:(a) hashCode() returns different values although
  two BigInteger objects are equivalent.(b) BigInteger.modPow()
  may return wrong result if JIT enables the quad
  optimization.Both of the two problems are caused by the
  BigInteger object's non-canonical internal representation when
  creating with modInverse. The internal representation array is
  not equivalent with the ones created otherwise, e.g. from a
  string or another BigInteger object.
  

Problem conclusion

• BigInteger has been enhanced to ensure internal representation
  is canonical.
  .
  This APAR will be fixed in the following Java Releases:
     7    SR8       (7.0.8.0)
     7 R1 SR2       (7.1.2.0)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, Java maintenance is available
  from:
             https://www.ibm.com/developerworks/java/jdk/
  

Temporary fix

• N/A
  

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

  JAVA CLASS LIBS

• Fixed component ID

  620700130

Applicable component levels

• R700 PSY

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