AlgorithmParameterSpec
public class GCMParameterSpec extends Object implements AlgorithmParameterSpec
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.
Constructor | Description |
---|---|
GCMParameterSpec |
Constructs a GCMParameterSpec using the specified authentication tag bit-length and IV buffer. |
GCMParameterSpec |
Constructs a GCMParameterSpec object using the specified authentication tag bit-length and a subset of the specified buffer as the IV. |
public GCMParameterSpec(int tLen, byte[] src)
tLen
- the authentication tag length (in bits)src
- the IV source buffer. The contents of the buffer are copied to protect against subsequent modification.IllegalArgumentException
- if tLen
is negative, or src
is null.public GCMParameterSpec(int tLen, byte[] src, int offset, int len)
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 in src
where the IV startslen
- the number of IV bytesIllegalArgumentException
- if tLen
is negative, src
is null, len
or offset
is negative, or the sum of offset
and len
is greater than the length of the src
byte array.public int getTLen()
public byte[] getIV()
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/javax/crypto/spec/GCMParameterSpec.html