* Testing for all zeros.
* This function returns 1 if the nlen bytes vector pointed by n contains only zeros.
* It returns 0 if non-zero bits are found.<br>
* Its execution time is constant for a given length.<br>
* This function was introduced in libsodium 1.0.7.
* Testing for all zeros. * This function returns 1 if the nlen bytes vector pointed by n contains only zeros. * It returns 0 if non-zero bits are found.<br> * Its execution time is constant for a given length.<br> * This function was introduced in libsodium 1.0.7.