Class GCMParameterSpec
- java.lang.Object
-
- javax.crypto.spec.GCMParameterSpec
- All Implemented Interfaces:
AlgorithmParameterSpec
public class GCMParameterSpec extends Object implements AlgorithmParameterSpec
Specifies the set of parameters required by a Cipher
using the Galois/Counter Mode (GCM) mode.
Simple block cipher modes (such as CBC) generally require only an initialization vector (such as IvParameterSpec
), but GCM needs these parameters:
-
IV
: Initialization Vector (IV) -
tLen
: length (in bits) of authentication tag T
In addition to the parameters described here, other GCM inputs/output (Additional Authenticated Data (AAD), Keys, block ciphers, plain/ciphertext and authentication tags) are handled in the
Cipher
class.
Please see RFC 5116 for more information on the Authenticated Encryption with Associated Data (AEAD) algorithm, and NIST Special Publication 800-38D, "NIST Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC."
The GCM specification states that tLen
may only have the values {128, 120, 112, 104, 96}, or {64, 32} for certain applications. Other values can be specified for this class, but not all CSP implementations will support them.
- Since:
- 1.7
- See Also:
Cipher
Constructor Summary
Constructor | Description |
---|---|
GCMParameterSpec(int tLen,
byte[] src) | Constructs a GCMParameterSpec using the specified authentication tag bit-length and IV buffer. |
GCMParameterSpec(int tLen,
byte[] src,
int offset,
int len) | Constructs a GCMParameterSpec object using the specified authentication tag bit-length and a subset of the specified buffer as the IV. |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
byte[] | getIV() | Returns the Initialization Vector (IV). |
int | getTLen() | Returns the authentication tag length. |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Constructor Detail
GCMParameterSpec
public GCMParameterSpec(int tLen, byte[] src)
Constructs a GCMParameterSpec using the specified authentication tag bit-length and IV buffer.
- Parameters:
-
tLen
- the authentication tag length (in bits) -
src
- the IV source buffer. The contents of the buffer are copied to protect against subsequent modification. - Throws:
-
IllegalArgumentException
- iftLen
is negative, orsrc
is null.
GCMParameterSpec
public GCMParameterSpec(int tLen, byte[] src, int offset, int len)
Constructs a GCMParameterSpec object using the specified authentication tag bit-length and a subset of the specified buffer as the IV.
- Parameters:
-
tLen
- the authentication tag length (in bits) -
src
- the IV source buffer. The contents of the buffer are copied to protect against subsequent modification. -
offset
- the offset insrc
where the IV starts -
len
- the number of IV bytes - Throws:
-
IllegalArgumentException
- iftLen
is negative,src
is null,len
oroffset
is negative, or the sum ofoffset
andlen
is greater than the length of thesrc
byte array.
Method Detail
getTLen
public int getTLen()
Returns the authentication tag length.
- Returns:
- the authentication tag length (in bits)
getIV
public byte[] getIV()
Returns the Initialization Vector (IV).
- Returns:
- the IV. Creates a new array each time this method is called.