Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly.
ConstantTimeByteEq returns 1 if x == y and 0 otherwise.
ConstantTimeCompare returns 1 iff the two equal length slices, x and y, have equal contents. The time taken is a function of the length of the slices and is independent of the contents.
ConstantTimeCopy copies the contents of y into x iff v == 1. If v == 0, x is left unchanged. Its behavior is undefined if v takes any other value.
ConstantTimeEq returns 1 if x == y and 0 otherwise.
ConstantTimeSelect returns x if v is 1 and y if v is 0. Its behavior is undefined if v takes any other value.