net.named_data.jndn.util

Class Common

java.lang.Object

net.named_data.jndn.util.Common

public class Common
extends Object

The Common class has static utility functions.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_NDN_PACKET_SIZE The practical limit of the size of a network-layer packet.

Constructor Summary

Constructors

Constructor and Description
Common()

Method Summary

Modifier and Type	Method and Description
static byte[]	base64Decode(String encoding) Decode the input as base64 using the appropriate base64Converter_ from establishBase64Converter(), for ANDROID or Java 7+.
static String	base64Encode(byte[] input) Encode the input as base64 using the appropriate base64Converter_ from establishBase64Converter(), for ANDROID or Java 7+.
static String	base64Encode(byte[] input, boolean addNewlines) Encode the input as base64 using the appropriate base64Converter_ from establishBase64Converter(), for ANDROID or Java 7+.
static byte[]	computeHmacWithSha256(byte[] key, ByteBuffer data) Compute the HMAC with SHA-256 of data, as defined in http://tools.ietf.org/html/rfc2104#section-2 .
static byte[]	computePbkdf2WithHmacSha1(byte[] password, byte[] salt, int nIterations, int resultLength) Compute the PBKDF2 with HMAC SHA1 of the password.
static byte[]	computePbkdf2WithHmacSha1(char[] password, byte[] salt, int nIterations, int resultLength) Compute the PBKDF2 with HMAC SHA1 of the password.
static long	dateToMillisecondsSince1970(Date date) Convert a Date object milliseconds.
static byte[]	digestSha256(byte[] data) Compute the sha-256 digest of data.
static byte[]	digestSha256(ByteBuffer data) Compute the sha-256 digest of data.
static File	getCurrentDirectory() Get the current directory.
static File	getHomeDirectory() Get the user's home directory.
static double	getNowMilliseconds() Get the current time in milliseconds.
static Random	getRandom() Get the library-wide random number generator.
static Date	millisecondsSince1970ToDate(long millisecondsSince1970) Convert the milliseconds to a Date object.
static boolean	platformIsOSX() Return true if the platform is OS X.
static void	setRandom(Random randomNumberGenerator) Set the library-wide random number generator; this method will only allow the generator to be set once.
static String	toHex(byte[] buffer) Return a hex string of the contents of buffer.

Methods inherited from class java.lang.Object

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

Field Detail

MAX_NDN_PACKET_SIZE

public static final int MAX_NDN_PACKET_SIZE

The practical limit of the size of a network-layer packet. If a packet is larger than this, the library or application MAY drop it. This constant is defined in this low-level class so that internal code can use it, but applications should use the static API method Face.getMaxNdnPacketSize() which is equivalent.

See Also:

Constant Field Values

Constructor Detail

Common

public Common()

Method Detail

getNowMilliseconds

public static double getNowMilliseconds()

Get the current time in milliseconds.

Returns:

The current time in milliseconds since 1/1/1970 UTC.

getRandom

public static Random getRandom()

Get the library-wide random number generator. This method is synchronized so that multiple accesses to the generator when a generator is not yet set will not throw an UnsupportedOperationException

Returns:

the random number generator set in setRandom(Random) or (by default) a SecureRandom

setRandom

public static void setRandom(Random randomNumberGenerator)

Set the library-wide random number generator; this method will only allow the generator to be set once. Additionally, this method is thread-safe in that it guarantees that only the first caller will be able to set the generator.

Parameters:

randomNumberGenerator - the random number generator

Throws:

UnsupportedOperationException - if a user attempts to set the generator a second time

digestSha256

public static byte[] digestSha256(ByteBuffer data)

Compute the sha-256 digest of data.

Parameters:

data - The input byte buffer. This does not change the position.

Returns:

The digest.

digestSha256

public static byte[] digestSha256(byte[] data)

Compute the sha-256 digest of data.

Parameters:

data - The input byte buffer.

Returns:

The digest.

computeHmacWithSha256

public static byte[] computeHmacWithSha256(byte[] key,
                                           ByteBuffer data)

Compute the HMAC with SHA-256 of data, as defined in http://tools.ietf.org/html/rfc2104#section-2 .

Parameters:

key - The key byte array.

data - The input byte buffer.

Returns:

The HMAC result.

computePbkdf2WithHmacSha1

public static byte[] computePbkdf2WithHmacSha1(char[] password,
                                               byte[] salt,
                                               int nIterations,
                                               int resultLength)
                                        throws NoSuchAlgorithmException,
                                               InvalidKeySpecException

Compute the PBKDF2 with HMAC SHA1 of the password.

Parameters:

password - The input password, which should have characters in the range of 1 to 127.

salt - The 8-byte salt.

nIterations - The number of iterations of the hashing algorithm.

resultLength - The number of bytes of the result array.

Returns:

The result byte array.

Throws:

NoSuchAlgorithmException

InvalidKeySpecException

computePbkdf2WithHmacSha1

public static byte[] computePbkdf2WithHmacSha1(byte[] password,
                                               byte[] salt,
                                               int nIterations,
                                               int resultLength)
                                        throws NoSuchAlgorithmException,
                                               InvalidKeySpecException

Compute the PBKDF2 with HMAC SHA1 of the password.

Parameters:

password - The input password, which should have values in the range of 1 to 127.

salt - The 8-byte salt.

nIterations - The number of iterations of the hashing algorithm.

resultLength - The number of bytes of the result array.

Returns:

The result byte array.

Throws:

NoSuchAlgorithmException

InvalidKeySpecException

toHex

public static String toHex(byte[] buffer)

Return a hex string of the contents of buffer.

Parameters:

buffer - The buffer.

Returns:

A string of hex bytes.

base64Encode

public static String base64Encode(byte[] input)

Encode the input as base64 using the appropriate base64Converter_ from establishBase64Converter(), for ANDROID or Java 7+.

Parameters:

input - The bytes to encode.

Returns:

The base64 string.

Throws:

UnsupportedOperationException - If can't establish a base64 converter for this platform.

base64Encode

public static String base64Encode(byte[] input,
                                  boolean addNewlines)

Encode the input as base64 using the appropriate base64Converter_ from establishBase64Converter(), for ANDROID or Java 7+.

Parameters:

input - The bytes to encode.

addNewlines - If true, add newlines to the output (good for writing to a file). If false, do not add newlines.

Returns:

The base64 string.

Throws:

UnsupportedOperationException - If can't establish a base64 converter for this platform.

base64Decode

public static byte[] base64Decode(String encoding)
                           throws SecurityException

Decode the input as base64 using the appropriate base64Converter_ from establishBase64Converter(), for ANDROID or Java 7+.

Parameters:

encoding - The base64 string.

Returns:

The decoded bytes.

Throws:

UnsupportedOperationException - If can't establish a base64 converter for this platform.

SecurityException

millisecondsSince1970ToDate

public static Date millisecondsSince1970ToDate(long millisecondsSince1970)

Convert the milliseconds to a Date object. This is a centralized utility method to support portability.

Parameters:

millisecondsSince1970 - The milliseconds since 1970.

Returns:

A new Date object.

dateToMillisecondsSince1970

public static long dateToMillisecondsSince1970(Date date)

Convert a Date object milliseconds. This is a centralized utility method to support portability.

Parameters:

date - the Date object.

Returns:

The milliseconds since 1970.

platformIsOSX

public static boolean platformIsOSX()

Return true if the platform is OS X.

Returns:

True if OS X, false if not.

getHomeDirectory

public static File getHomeDirectory()

Get the user's home directory.

Returns:

The home directory as a File object, or new File(".") if unknown.

getCurrentDirectory

public static File getCurrentDirectory()

Get the current directory.

Returns:

The current directory as a File object.