package subtle

Import Path
	crypto/subtle (on go.dev)

Dependency Relation
	imports 3 packages, and imported by 9 packages

Involved Source Files

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

	    dit.go
	    xor.go
Package-Level Functions (total 8)

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

	 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(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(x, y int32) int
		ConstantTimeEq returns 1 if x == y and 0 otherwise.

	 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(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 WithDataIndependentTiming(f func())
		WithDataIndependentTiming enables architecture specific features which ensure
		that the timing of specific instructions is independent of their inputs
		before executing f. On f returning it disables these features.
		
		WithDataIndependentTiming should only be used when f is written to make use
		of constant-time operations. WithDataIndependentTiming does not make
		variable-time code constant-time.
		
		WithDataIndependentTiming may lock the current goroutine to the OS thread for
		the duration of f. Calls to WithDataIndependentTiming may be nested.
		
		On Arm64 processors with FEAT_DIT, WithDataIndependentTiming enables
		PSTATE.DIT. See https://developer.arm.com/documentation/ka005181/1-0/?lang=en.
		
		Currently, on all other architectures WithDataIndependentTiming executes f immediately
		with no other side-effects.

	 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.
		
		dst and x or y may overlap exactly or not at all,
		otherwise XORBytes may panic.

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