org.apache.shindig.common.crypto
Class Crypto

java.lang.Object
  org.apache.shindig.common.crypto.Crypto

public final class Crypto
extends Object

Cryptographic utility functions.

Field Summary

static int	CIPHER_KEY_LEN Use keys of this length for encryption operations
static int	HMAC_SHA1_LEN Length of HMAC SHA1 output
static SecureRandom	RAND Use this random number generator instead of creating your own.

Method Summary

static byte[]	aes128cbcDecrypt(byte[] key, byte[] cipherText) AES-128-CBC decryption.
static byte[]	aes128cbcDecryptWithIv(byte[] key, byte[] iv, byte[] cipherText, int offset) AES-128-CBC decryption with a particular IV.
static byte[]	aes128cbcEncrypt(byte[] key, byte[] plain) AES-128-CBC encryption.
static byte[]	aes128cbcEncryptWithIV(byte[] key, byte[] iv, byte[] plain) AES-128-CBC encryption with a given IV.
static byte[]	concat(byte[] a, byte[] b) Concatenate two byte arrays.
static byte[]	getRandomBytes(int numBytes) Returns strong random bytes.
static String	getRandomDigits(int len)
static String	getRandomString(int numBytes) Gets a hex encoded random string.
static byte[]	hmacSha1(byte[] key, byte[] in) HMAC sha1
static void	hmacSha1Verify(byte[] key, byte[] in, byte[] expected) Verifies an HMAC SHA1 hash.

Methods inherited from class java.lang.Object

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

Field Detail

RAND

public static final SecureRandom RAND

Use this random number generator instead of creating your own. This is thread-safe.

CIPHER_KEY_LEN

public static final int CIPHER_KEY_LEN

Use keys of this length for encryption operations

See Also:

Constant Field Values

HMAC_SHA1_LEN

public static final int HMAC_SHA1_LEN

Length of HMAC SHA1 output

See Also:

Constant Field Values

Method Detail

getRandomString

public static String getRandomString(int numBytes)

Gets a hex encoded random string.

Parameters:

numBytes - number of bytes of randomness.

getRandomDigits

public static String getRandomDigits(int len)

Returns:

a random string of digits of the specified length.

getRandomBytes

public static byte[] getRandomBytes(int numBytes)

Returns strong random bytes.

Parameters:

numBytes - number of bytes of randomness

hmacSha1

public static byte[] hmacSha1(byte[] key,
                              byte[] in)
                       throws GeneralSecurityException

HMAC sha1

Parameters:

key - the key must be at least 8 bytes in length.

in - byte array to HMAC.

Returns:

the hash

Throws:

GeneralSecurityException

hmacSha1Verify

public static void hmacSha1Verify(byte[] key,
                                  byte[] in,
                                  byte[] expected)
                           throws GeneralSecurityException

Verifies an HMAC SHA1 hash. Throws if the verification fails.

Parameters:

key -

in -

expected -

Throws:

GeneralSecurityException

aes128cbcEncrypt

public static byte[] aes128cbcEncrypt(byte[] key,
                                      byte[] plain)
                               throws GeneralSecurityException

AES-128-CBC encryption. The IV is returned as the first 16 bytes of the cipher text.

Parameters:

key -

plain -

Returns:

the IV and cipher text

Throws:

GeneralSecurityException

aes128cbcEncryptWithIV

public static byte[] aes128cbcEncryptWithIV(byte[] key,
                                            byte[] iv,
                                            byte[] plain)
                                     throws GeneralSecurityException

AES-128-CBC encryption with a given IV.

Parameters:

key -

iv -

plain -

Returns:

the cipher text

Throws:

GeneralSecurityException

aes128cbcDecrypt

public static byte[] aes128cbcDecrypt(byte[] key,
                                      byte[] cipherText)
                               throws GeneralSecurityException

AES-128-CBC decryption. The IV is assumed to be the first 16 bytes of the cipher text.

Parameters:

key -

cipherText -

Returns:

the plain text

Throws:

GeneralSecurityException

aes128cbcDecryptWithIv

public static byte[] aes128cbcDecryptWithIv(byte[] key,
                                            byte[] iv,
                                            byte[] cipherText,
                                            int offset)
                                     throws GeneralSecurityException

AES-128-CBC decryption with a particular IV.

Parameters:

key - decryption key

iv - initial vector for decryption

cipherText - cipher text to decrypt

offset - offset into cipher text to begin decryption

Returns:

the plain text

Throws:

GeneralSecurityException

concat

public static byte[] concat(byte[] a,
                            byte[] b)

Concatenate two byte arrays.