subtle

Documentation

Overview

Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly.

Index

• func ConstantTimeByteEq(x, y uint8) int
• func ConstantTimeCompare(x, y []byte) int
• func ConstantTimeCopy(v int, x, y []byte)
• func ConstantTimeEq(x, y int32) int
• func ConstantTimeLessOrEq(x, y int) int
• func ConstantTimeSelect(v, x, y int) int
• func XORBytes(dst, x, y []byte) int

Functions

func ConstantTimeByteEq

func ConstantTimeByteEq(x, y uint8) int

ConstantTimeByteEq returns 1 if x == y and 0 otherwise.

func ConstantTimeCompare

func ConstantTimeCompare(x, y []byte) int

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 ConstantTimeCopy

func ConstantTimeCopy(v int, x, y []byte)

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 ConstantTimeEq

func ConstantTimeEq(x, y int32) int

ConstantTimeEq returns 1 if x == y and 0 otherwise.

func ConstantTimeLessOrEq

func ConstantTimeLessOrEq(x, y int) int

ConstantTimeLessOrEq returns 1 if x <= y and 0 otherwise. Its behavior is undefined if x or y are negative or > 2**31 - 1.

func ConstantTimeSelect

func ConstantTimeSelect(v, x, y int) int

ConstantTimeSelect returns x if v == 1 and y if v == 0. Its behavior is undefined if v takes any other value.

func XORBytes

func XORBytes(dst, x, y []byte) int

XORBytes sets dst[i] = x[i] ^ y[i] for all i < n = min(len(x), len(y)), returning n, the number of bytes written to dst. If dst does not have length at least n, XORBytes panics without writing anything to dst.