@Override public List<StrictBitVector> extend(StrictBitVector choices) { // The underlying scheme requires computational security parameter plus lambda security // parameter extra OTs int minOts = choices.getSize() + resources.getComputationalSecurityParameter() + resources .getLambdaSecurityParam(); // Round up to nearest two-power, which is required by the underlying scheme int ellPrime = (int) Math.pow(2, Math.ceil(Math.log(minOts) / Math.log(2))); // Extend the choices with random choices for padding StrictBitVector paddingChoices = new StrictBitVector(ellPrime - choices.getSize(), resources .getRandomGenerator()); StrictBitVector extendedChoices = StrictBitVector.concat(choices, paddingChoices); // Use the choices along with the random padding uses for correlated OT with // errors List<StrictBitVector> tlist = receiver.extend(extendedChoices); // Agree on challenges for linear combination test List<StrictBitVector> chiList = getChallenges(ellPrime); StrictBitVector xvec = computeBitLinearCombination(extendedChoices, chiList); network.send(resources.getOtherId(), xvec.toByteArray()); StrictBitVector tvec = computeInnerProduct(chiList, tlist); network.send(resources.getOtherId(), tvec.toByteArray()); // Remove the correlation of the OTs by hashing List<StrictBitVector> vvec = hashBitVector(tlist, choices.getSize()); return vvec; }