'getKeyPair', function(cert, params, callback) {
   getPublicKey(cert, params, function(publicKey, algorithm) {
     if (chrome.runtime.lastError) {
       callback();
       return;
     }
     callback(createPublicKey(publicKey, algorithm),
              createPrivateKey(publicKey, algorithm));
   });
 });
 'getKeyPair', function(cert, params, callback) {
   getPublicKey(cert, params, function(publicKey, algorithm) {
     callback(createPublicKey(publicKey, algorithm),
              createPrivateKey(publicKey, algorithm));
   });
 });