go/src/crypto/subtle/constant_time.go

// ConstantTimeCompare returns 1 if the two slices, x and y, have equal contents
// and 0 otherwise. The time taken is a function of the length of the slices and
// is independent of the contents. If the lengths of x and y do not match it
// returns 0 immediately.
func ConstantTimeCompare(x, y []byte) int { … }

// ConstantTimeSelect returns x if v == 1 and y if v == 0.
// Its behavior is undefined if v takes any other value.
func ConstantTimeSelect(v, x, y int) int { … }

// ConstantTimeByteEq returns 1 if x == y and 0 otherwise.
func ConstantTimeByteEq(x, y uint8) int { … }

// ConstantTimeEq returns 1 if x == y and 0 otherwise.
func ConstantTimeEq(x, y int32) int { … }

// ConstantTimeCopy copies the contents of y into x (a slice of equal length)
// if v == 1. If v == 0, x is left unchanged. Its behavior is undefined if v
// takes any other value.
func ConstantTimeCopy(v int, x, y []byte) { … }

// ConstantTimeLessOrEq returns 1 if x <= y and 0 otherwise.
// Its behavior is undefined if x or y are negative or > 2**31 - 1.
func ConstantTimeLessOrEq(x, y int) int { … }