Coverity warning about code in smult_curve25519_ref.c

[Andrew Worsley <amworsley@xxxxxxxxx>]

Hi can some one point me to someone who understands how the following
code in smult_curve25519_ref.c

square() is *NOT* a buffer overrun.

I understand that it is called from places with 64 entry arrays but still

 unsigned int c1[64];
....
square(r,c1 + 32); - where c1 is a 64 entry array sounds dangerous.

Where:

static void square(unsigned int out[32],const unsigned int a[32])
{
  unsigned int i;
  unsigned int j;
  unsigned int u;

  for (i = 0;i < 32;++i) {
    u = 0;
    for (j = 0;j < i - j;++j) u += a[j] * a[i - j];
    for (j = i + 1;j < i + 32 - j;++j) u += 38 * a[j] * a[i + 32 - j];
    u *= 2;
    if ((i & 1) == 0) {
      u += a[i / 2] * a[i / 2];
      u += 38 * a[i / 2 + 16] * a[i / 2 + 16];
    }
    out[i] = u;
  }
  squeeze(out);
}

Even if this code is valid - would it not be wise to ask someone to
revise it to be more transparent and easily verifiable?

Thanks

Andrew
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