C++ EncryptedArray::rotate1D方法代码示例

void replicate0(const EncryptedArray& ea, Ctxt& ctxt, long pos)
{
  long dim = ea.dimension();

  for (long d = 0; d < dim; d++) {
    if (!ea.nativeDimension(d)) {
      long shamt = -ea.coordinate(d, pos);
      ea.rotate1D(ctxt, d, shamt, true); // "don't care"
    }

    Ctxt ctxt_orig = ctxt; 

    long sz = ea.sizeOfDimension(d);
    long k = NumBits(sz);
    long e = 1;

    // now process bits k-2 down to 0
    for (long j = k-2; j >= 0; j--) {
      // e -> 2*e
      Ctxt tmp = ctxt;
      ea.rotate1D(tmp, d, e, true); // "don't care"
      ctxt += tmp;
      e = 2*e;
      
      long b = bit(sz, j); // bit j of sz
      // e -> e+b
      if (b) {
        ea.rotate1D(ctxt, d, 1, true); // "don't care"
        ctxt += ctxt_orig;
        e++;
      }
    }
  }
}

static void replicateOneBlock(const EncryptedArray& ea, Ctxt& ctxt, 
			      long pos, long blockSize, long d)
{
  long dSize = ea.sizeOfDimension(d);

  // Move this block to position 0. We can skip this step in
  // "good dimensions" of size divisible by the block size
  if (pos != 0 &&  (!ea.nativeDimension(d) || dSize % blockSize != 0) ) {
    ea.rotate1D(ctxt, d, -pos*blockSize, true);
  }

  long sz = dSize/blockSize; // how many blocks fit in this dimension

  if (sz == 1) return; // nothing to do, only one block in this dimension

  // do the actual replication using "shift and add"

  long k = NumBits(sz);
  long e = 1;
  Ctxt ctxt_orig = ctxt;

  // now process bits k-2 down to 0
  for (long j = k-2; j >= 0; j--) {
    // e -> 2*e
    Ctxt tmp = ctxt;
    ea.rotate1D(tmp, d, e*blockSize, /*don't-care-flag=*/true);
    ctxt += tmp;
    e = 2*e;
    
    long b = bit(sz, j); // bit j of sz
    // e -> e+b
    if (b) {
      ea.rotate1D(ctxt, d, 1*blockSize, /*don't-care-flag=*/true);
      ctxt += ctxt_orig;
      e++;
    }
  }
}

//.........这里部分代码省略.........
  //
  // The call to recursiveReplicateDim (still with k=2) will first copy
  // s0/s1 and s4/s5 to the zero column at the end, then make a recursive
  // call with k=1 that will complete the replication along the current
  // dimension, resulting in the 4 ciphertexts
  // 
  //  (s0 s0 s0 s0 s0) (s2 s2 s2 s2 s2) (s4 s4 s4 s4 s4) (s6 s6 s6 s6 s6)
  //  (s1 s1 s1 s1 s1) (s3 s3 s3 s3 s3) (s5 s5 s5 s5 s5) (s7 s7 s7 s7 s7)
  //
  // Then a recursive call for the next dimension will complete the
  // replication of these entries, and a final step will deal with the
  // "leftover" positions s8 s9
  


  // The logic below cut the recursion depth by starting from smaller
  // blocks (by default size approx n rather than 2^n).
  // The inital block size is controlled by the recBound parameter:
  //   + recBound>0: blocks of size min(~n, 2^recBound). this ensures
  //     recursion depth <= recBound, and typically much smaller (~log n)
  //   + recBound=0: blocks of size 1 (no recursion)
  //   + recBound<0: blocks of size 2^n (full recursion)

  if (recBound >= 0) { // use heuristic recursion bound
    k = 0;
    if (dSize > 2 && dimProd*NumBits(dSize) > ea.size() / 8) {
      k = NumBits(NumBits(dSize))-1;
      if (k > n) k = n;
      if (k > recBound) k = recBound;
    }
  }
  else { // SHAI: I don't understand this else case
    k = -recBound;
    if (k > n) k = n;
  }

  long blockSize = 1L << k;        // blocks of size 2^k
  long numBlocks = dSize/blockSize;
  long extent = numBlocks * blockSize;

  // extent is an integral multiple of the block size, the recursive
  // call replicates only these slots, and then we have a separate
  // call for the leftover slots.

  Ctxt ctxt1 = ctxt;

  if (extent < dSize) { // select only the slots 0..extent-1 in this dimension
    if (repAux.tab1(d, 0).null()) { // generate mask if not already there
      ZZX mask;
      SelectRangeDim(ea, mask, 0, extent, d);
      repAux.tab1(d, 0).set_ptr(new DoubleCRT(mask, ea.getContext()));
      // store mask in 2nd table (tab1)
    }
    ctxt1.multByConstant(*repAux.tab1(d, 0)); // mult by mask to zero out slots
  }

  if (numBlocks == 1) { // just one block, call the recursive replication
    recursiveReplicateDim(ea, ctxt1, d, extent, k, 0, extent, 
                          dimProd, recBound, repAux, handler);
  }
  else { // replicate the slots in each block separately
    for (long pos = 0; pos < numBlocks; pos++) {
      Ctxt ctxt2 = ctxt1;
      // zero-out all the slots outside the current block
      SelectRangeDim(ea, ctxt2, pos*blockSize, (pos+1)*blockSize, d);

      // replicate the current block across this dimenssion using a
      // simple shift-and-add procedure.
      replicateOneBlock(ea, ctxt2, pos, blockSize, d);

      // now call the recursive replication to do the rest of the work
      recursiveReplicateDim(ea, ctxt2, d, extent, k, 0, extent, 
                            dimProd, recBound, repAux, handler);
    }
  }

  // If dSize is not an integral number of blocks, then we still need
  // to deal with the leftover slots.
  if (extent < dSize) {
    // zero-out the slots from before, leaving only the leftover slots
    ctxt1 = ctxt;
    if (repAux.tab1(d, 1).null()) { // generate mask if not already there
      ZZX mask;
      SelectRangeDim(ea, mask, extent, dSize, d);
      repAux.tab1(d, 1).set_ptr(new DoubleCRT(mask, ea.getContext()));
    }
    ctxt1.multByConstant(*repAux.tab1(d,1)); // mult by mask to zero out slots

    // move relevant slots to the beginning
    ea.rotate1D(ctxt1, d, -extent, /*don't-care-flag=*/true);

    // replicate the leftover block across this dimenssion using a
    // simple shift-and-add procedure.
    replicateOneBlock(ea, ctxt1, 0, blockSize, d);

    // now call the recursive replication to do the rest of the work
    recursiveReplicateDim(ea, ctxt1, d, extent, k, extent, dSize, 
                          dimProd, recBound, repAux, handler);
  }
}

// recursiveReplicateDim:
//   d = dimension
//   ea.sizeOfDimension(d)/2 <= extent <= ea.sizeOfDimension(d),
//     only positions [0..extent) are non-zero
//   1 <= 2^k <= extent: size of current interval
//   0 <= pos < ea.sizeOfDimension(d): relative position of first vector
//   0 <= limit < ea.sizeOfDimension(): max # of positions to process
//   dimProd: product of dimensions 0..d
//   recBound: recursion bound (controls noise) 
//
// SHAI: limit and extent are always the same, it seems
static
void recursiveReplicateDim(const EncryptedArray& ea, const Ctxt& ctxt, 
                           long d, long extent, long k, long pos, long limit,  
                           long dimProd, long recBound,
                           RepAuxDim& repAux,
                           ReplicateHandler *handler)
{
  if (pos >= limit) return;

  if (replicateVerboseFlag) { // DEBUG code
    cerr << "check: " << k; CheckCtxt(ctxt, "");
  }
  
  long dSize = ea.sizeOfDimension(d);
  long nSlots = ea.size();

  if (k == 0) { // last level in this dimension: blocks of size 2^k=1

    if ( extent >= dSize) { // nothing to do in this dimension
      replicateAllNextDim(ea, ctxt, d+1, dimProd, recBound, repAux, handler);
      return;
    } // SHAI: Will we ever have extent > dSize??

    // need to replicate to fill positions [ (1L << n) .. dSize-1 ]

    if (repAux.tab(d,0).null()) { // generate mask if not there already
      ZZX mask;
      SelectRangeDim(ea, mask, 0, dSize - extent, d);
      repAux.tab(d, 0).set_ptr(new DoubleCRT(mask, ea.getContext()));
    }

    Ctxt ctxt_tmp = ctxt;
    ctxt_tmp.multByConstant(*repAux.tab(d, 0));

    ea.rotate1D(ctxt_tmp, d, extent, /*don't-care-flag=*/true);
    ctxt_tmp += ctxt;
    replicateAllNextDim(ea, ctxt_tmp, d+1, dimProd, recBound, repAux, handler);
    return;
  }

  // If we need to stop early, call the handler
  if (handler->earlyStop(d, k, dimProd)) {
    handler->handle(ctxt);
    return;
  }

  k--;
  Ctxt ctxt_masked = ctxt;

  {   // artificial scope to miminize storage in the recursion
    { // another artificial scope (SHAI: this seems redundant)

      // generate mask at index k+1, if not there yet

      if (repAux.tab(d, k+1).null()) { // need to generate
        vector< long > maskArray(nSlots,0);
        for (long i = 0; i < nSlots; i++) {
          long c = ea.coordinate(d, i);
          if (c < extent && bit(c, k) == 0)
            maskArray[i] = 1;
        }
	// store this mask in the repAux table
        ZZX mask;
        ea.encode(mask, maskArray);
        repAux.tab(d, k+1).set_ptr(new DoubleCRT(mask, ea.getContext()));
      }

      // Apply mask to zero out slots in ctxt
      ctxt_masked.multByConstant(*repAux.tab(d, k+1));
    }

    Ctxt ctxt_left = ctxt_masked;
    ea.rotate1D(ctxt_left, d, 1L << k, /*don't-care-flag=*/true);
    ctxt_left += ctxt_masked;

    recursiveReplicateDim(ea, ctxt_left, d, extent, k, pos, limit, 
                          dimProd, recBound, repAux, handler);
  }

  pos += (1L << k);
  if (pos >= limit)
    return;

  Ctxt ctxt_right = ctxt;
  ctxt_right -= ctxt_masked; 
  ctxt_masked = ctxt_right; // reuse ctxt_masked as a temp
  ea.rotate1D(ctxt_masked, d, -(1L << k), /*don't-care-flag=*/true);
  ctxt_right += ctxt_masked;

//.........这里部分代码省略.........