public final class CryptoUtils
extends java.lang.Object
| Modifier and Type | Method and Description |
|---|---|
static void |
arraycopy(byte[] src,
int srcPosition,
byte[] dst,
int dstPosition,
int length)
Copies the specified portion of one byte array into a given location in
another byte array.
|
static int |
bitLength(int i)
Determines the bit length of an integer.
|
static boolean |
checkExponentLength(java.security.interfaces.RSAPublicKey key)
Method used as a hook to determine if the exponent length should
be checked based on criteria that will be determined in a future
release.
|
static int |
countOneBits(byte b)
Counts the number of bits that are set to 1 in a byte.
|
static java.math.BigInteger |
enhancedMillerRabin(java.math.BigInteger w,
int iterations,
java.util.Random rnd)
Performs the enhanced Miller_Rabin tests, and Returns a BigInteger as
a result.
|
static byte[] |
getMagnitude(java.math.BigInteger bi)
Returns the big-endian binary representation of the magnitude of a
BigInteger. |
static int |
getMagnitudeSize(java.math.BigInteger bi)
Returns size (in bytes) of the big-endian binary representation of the
magnitude of a
BigInteger. |
static boolean |
isEqual(byte[] ba1,
byte[] ba2)
Compares two byte arrays for equality.
|
static boolean |
isEqual(byte[] ba1,
int offset1,
byte[] ba2,
int offset2,
int length)
Compares two byte array segments for equality.
|
static boolean |
isOdd(java.math.BigInteger bi)
Tests whether a given integer is odd.
|
static void |
setDESKeyParity(byte[] key,
int offset)
Sets the parity bits of a DES key.
|
static void |
setTripleDESKeyParity(byte[] key,
int offset)
Sets the parity bits of a DESede key.
|
public static void arraycopy(byte[] src,
int srcPosition,
byte[] dst,
int dstPosition,
int length)
This method is intended to give optimum performance during the array copy.
When less than 10 elements are being copied, the elements are copied
individually. When more that 10 elements are being copied the utility
System.arraycopy() is used to do the copy. This is done
because typically System.arraycopy() is only faster than
manual array* copying when there are more than 10 elements are being
copied.
src - the source byte arraysrcPosition - the start position in the source byte arraydst - the destination byte arraydstPosition - the start position in the destination byte arraylength - the number of bytes to be copiedpublic static byte[] getMagnitude(java.math.BigInteger bi)
BigInteger.
Note that the big-endian representation of the integer 0 is 0x00.
bi - the BigIntegerpublic static int getMagnitudeSize(java.math.BigInteger bi)
BigInteger.
Since the big-endian representation of the integer 0 is 0x00, the size of the magnitude in this case is 1.
bi - the BigIntegerpublic static int countOneBits(byte b)
b - the bytepublic static void setDESKeyParity(byte[] key,
int offset)
A DES key contains 8 error detecting bits (bits 8, 16, ..., 64) that are set to make the parity of each byte of the key odd. Odd parity indicates that there is an odd number of 1's in each byte.
key - the byte array containing the DES keyoffset - the location in the byte array where the key startspublic static void setTripleDESKeyParity(byte[] key,
int offset)
A DESede key consists of 3 DES keys. Each DES key contains 8 error detecting bits (bits 8, 16, ..., 64) that are set to make the parity of each byte of the key odd. Odd parity indicates that there is an odd number of 1's in each byte.
key - the byte array containing the DESede keyoffset - the location in the byte array where the key startspublic static boolean isOdd(java.math.BigInteger bi)
bi - the integer to be testedtrue if the integer is odd; false
otherwisepublic static boolean isEqual(byte[] ba1,
byte[] ba2)
Uses a time constant comparison algorithm that is immune to timing based attacks. For example, when verifying a MAC, it is important to use a time constant comparison. Otherwise, it may be possible to mount an attack that would expose the MAC value. In such situations, to prevent this type of timing attack, this API should be used instead of any of the following (which are not time constant):
java.util.Arrays.equals(byte[], byte[])iaik.utils.CryptoUtils.equalsBlock(byte[], byte[])ba1 - one byte array being tested in the equality checkba2 - the other byte array being tested in the equality checktrue if the two byte arrays are equal;
false otherwisepublic static boolean isEqual(byte[] ba1,
int offset1,
byte[] ba2,
int offset2,
int length)
Uses a time constant comparison algorithm that is immune to timing based attacks. For example, when verifying a MAC, it is important to use a time constant comparison. Otherwise, it may be possible to mount an attack that would expose the MAC value. In such situations, to prevent this type of timing attack, this API should be used instead of the following (which is not time constant):
iaik.utils.CryptoUtils.equalsBlock(byte[], int, byte[], int, int)
ba1 - one byte array from which a segment is being tested in the
equality checkoffset1 - the offset in ba1 where the byte array segment
startsba2 - the other byte array from which a segment is being tested in
the equality checkoffset2 - the offset in ba2 where the byte array segment
startslength - the length of the byte array segmentstrue if the two byte array segments are equal;
false otherwisepublic static int bitLength(int i)
The bit length is the number of bits in the minimal two's-complement representation of this integer. For positive integers, this is the equivalent of the number bits in the ordinary binary representation. For negative integers, this is always 32-bits.
This implementation is secure; it wipes all internal copies of the integer from memory upon completion. Thus, it is suitable for use with private or sensitive information.
i - an integerpublic static java.math.BigInteger enhancedMillerRabin(java.math.BigInteger w,
int iterations,
java.util.Random rnd)
If the BigInteger returned is 1, 1, the result is PROVABLY COMPOSITE AND NOT A POWER OF A PRIME.
If the BigInteger returned is 0, the result is probably prime. The following assumptions are made: This BigInteger is a positive, odd number greater than 2. iterations<=50.
w, - the BigInteger to testiterations, - the number of Miller-Rabin Iterationsrnd, - the Random number generatorpublic static boolean checkExponentLength(java.security.interfaces.RSAPublicKey key)