Package com.yahoo.security

Class SideChannelSafe

java.lang.Object

com.yahoo.security.SideChannelSafe

public class SideChannelSafe
extends Object

Utility functions for comparing the contents of arrays without leaking information about the data contained within them via timing side-channels. This is done by avoiding any branches that depend on the array elements themselves. This inherently means that all operations have both an upper and a lower bound in processing time that is O(n) for an array of size n, as there can be no early exits.

Author:

vekterli

Constructor Summary

Constructors

Constructor	Description
SideChannelSafe()

Method Summary

Modifier and Type	Method	Description
static boolean	allZeros(byte[] buf)
static boolean	arraysEqual(byte[] lhs, byte[] rhs)	Compare two byte arrays without the use of data-dependent branching that may leak information about the contents of either of the arrays.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SideChannelSafe

public SideChannelSafe()

Method Details

allZeros

public static boolean allZeros(byte[] buf)

Returns:

true iff all bytes in the array are zero. An empty array always returns true to be in line with BouncyCastle semantics.

arraysEqual

public static boolean arraysEqual(byte[] lhs,
 byte[] rhs)

Compare two byte arrays without the use of data-dependent branching that may leak information about the contents of either of the arrays. Important: the length of the arrays is not considered secret, and may be leaked if arrays of differing sizes are given.

Parameters:

lhs - first array of bytes to compare

rhs - second array of bytes to compare

Returns:

true iff both arrays have the same size and are element-wise identical