The U2 is a spy plane. U2 is also the name of a rock group from Ireland that in a couple of 1980s songs paid tribute to Martin Luther King Jr. and then got into a public spat with the governor of Arizona for rescinding that state's observance of the King holiday.

Now a national holiday, the King commemoration fell this year on the same day that RSA Data Security Inc. opened its annual conference on data encryption and related technologies. Intelligence gatherers-the people behind the U2, for example-depend on such systems to prevent sensitive information from falling into the wrong hands.

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