public final Class ConstantTimeUtils

Compare two ints without leaking timing information.

The int return type is intentional and is designed to allow cascading of constant time operations:

    int l1 = 1;
    int l2 = 1;
    int l3 = 1;
    int l4 = 500;
    boolean equals = (equalsConstantTime(l1, l2) & equalsConstantTime(l3, l4)) != 0;

Parameters

x:int

the first value.

y:int

the second value.

Returns:int

0 if not equal. 1 if equal.

Compare two longss without leaking timing information.

The int return type is intentional and is designed to allow cascading of constant time operations:

    long l1 = 1;
    long l2 = 1;
    long l3 = 1;
    long l4 = 500;
    boolean equals = (equalsConstantTime(l1, l2) & equalsConstantTime(l3, l4)) != 0;

Parameters

x:long

the first value.

y:long

the second value.

Returns:int

0 if not equal. 1 if equal.

Compare two byte arrays for equality without leaking timing information. For performance reasons no bounds checking on the parameters is performed.

The int return type is intentional and is designed to allow cascading of constant time operations:

    byte[] s1 = new {1, 2, 3};
    byte[] s2 = new {1, 2, 3};
    byte[] s3 = new {1, 2, 3};
    byte[] s4 = new {4, 5, 6};
    boolean equals = (equalsConstantTime(s1, 0, s2, 0, s1.length) &
                      equalsConstantTime(s3, 0, s4, 0, s3.length)) != 0;

Parameters

bytes1:byte[]

the first byte array.

startPos1:int

the position (inclusive) to start comparing in bytes1.

bytes2:byte[]

the second byte array.

startPos2:int

the position (inclusive) to start comparing in bytes2.

length:int

the amount of bytes to compare. This is assumed to be validated as not going out of bounds by the caller.

Returns:int

0 if not equal. 1 if equal.

Compare two CharSequence objects without leaking timing information.

The int return type is intentional and is designed to allow cascading of constant time operations:

    String s1 = "foo";
    String s2 = "foo";
    String s3 = "foo";
    String s4 = "goo";
    boolean equals = (equalsConstantTime(s1, s2) & equalsConstantTime(s3, s4)) != 0;

Parameters

s1:CharSequence

the first value.

s2:CharSequence

the second value.

Returns:int

0 if not equal. 1 if equal.