Package com.impossibl.postgres.protocol.sasl.scram.util

Class CryptoUtil

java.lang.Object

com.impossibl.postgres.protocol.sasl.scram.util.CryptoUtil

public class CryptoUtil
extends Object

Utility static methods for cryptography related tasks.

Constructor Summary

Constructors

Constructor	Description
CryptoUtil()

Method Summary

Modifier and Type	Method	Description
static byte[]	hi(SecretKeyFactory secretKeyFactory, int keyLength, char[] value, byte[] salt, int iterations)	Compute the "Hi" function for SCRAM.
static byte[]	hmac(SecretKeySpec secretKeySpec, Mac mac, byte[] message)	Computes the HMAC of a given message.
static String	nonce(int size, SecureRandom random)	Generates a random string (called a 'nonce'), composed of ASCII printable characters, except comma (',').
static byte[]	xor(byte[] value1, byte[] value2)	Computes a byte-by-byte xor operation.

Methods inherited from class java.lang.Object

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

Constructor Detail

CryptoUtil

public CryptoUtil()

Method Detail

nonce

public static String nonce(int size,
                           SecureRandom random)

Generates a random string (called a 'nonce'), composed of ASCII printable characters, except comma (',').

Parameters:

size - The length of the nonce, in characters/bytes

random - The SecureRandom to use

Returns:

The String representing the nonce

hi

public static byte[] hi(SecretKeyFactory secretKeyFactory,
                        int keyLength,
                        char[] value,
                        byte[] salt,
                        int iterations)

Compute the "Hi" function for SCRAM. Hi(str, salt, i): U1 := HMAC(str, salt + INT(1)) U2 := HMAC(str, U1) ... Ui-1 := HMAC(str, Ui-2) Ui := HMAC(str, Ui-1) Hi := U1 XOR U2 XOR ... XOR Ui where "i" is the iteration count, "+" is the string concatenation operator, and INT(g) is a 4-octet encoding of the integer g, most significant octet first. Hi() is, essentially, PBKDF2 [RFC2898] with HMAC() as the pseudorandom function (PRF) and with dkLen == output length of HMAC() == output length of H().

Parameters:

secretKeyFactory - The SecretKeyFactory to generate the SecretKey

keyLength - The length of the key (in bits)

value - The char array to compute the Hi function

salt - The salt

iterations - The number of iterations

Returns:

The bytes of the computed Hi value

hmac

public static byte[] hmac(SecretKeySpec secretKeySpec,
                          Mac mac,
                          byte[] message)

Computes the HMAC of a given message. HMAC(key, str): Apply the HMAC keyed hash algorithm (defined in [RFC2104]) using the octet string represented by "key" as the key and the octet string "str" as the input string. The size of the result is the hash result size for the hash function in use. For example, it is 20 octets for SHA-1 (see [RFC3174]).

Parameters:

secretKeySpec - A key of the given algorithm

mac - A MAC instance of the given algorithm

message - The message to compute the HMAC

Returns:

The bytes of the computed HMAC value

xor

public static byte[] xor(byte[] value1,
                         byte[] value2)
                  throws IllegalArgumentException

Computes a byte-by-byte xor operation. XOR: Apply the exclusive-or operation to combine the octet string on the left of this operator with the octet string on the right of this operator. The length of the output and each of the two inputs will be the same for this use.

Parameters:

value1 -

value2 -

Returns:

Throws:

IllegalArgumentException