public class Poly1305KeyGenerator extends CipherKeyGenerator
Poly1305 keys are 256 bit keys consisting of a 128 bit secret key used for the underlying block
cipher followed by a 128 bit r value used for the polynomial portion of the Mac.
The r value has a specific format with some bits required to be cleared, resulting in an
effective 106 bit key.
A separately generated 256 bit key can be modified to fit the Poly1305 key format by using the
clamp(byte[]) method to clear the required bits.
Poly1305random, strength| Constructor and Description |
|---|
Poly1305KeyGenerator() |
| Modifier and Type | Method and Description |
|---|---|
static void |
checkKey(byte[] key)
Checks a 32 byte key for compliance with the Poly1305 key requirements, e.g.
|
static void |
clamp(byte[] key)
Modifies an existing 32 byte key value to comply with the requirements of the Poly1305 key by
clearing required bits in the
r (second 16 bytes) portion of the key.Specifically: r[3], r[7], r[11], r[15] have top four bits clear (i.e., are {0, 1, . |
byte[] |
generateKey()
Generates a 256 bit key in the format required for Poly1305 - e.g.
|
void |
init(KeyGenerationParameters param)
Initialises the key generator.
Poly1305 keys are always 256 bits, so the key length in the provided parameters is ignored. |
public void init(KeyGenerationParameters param)
init in class CipherKeyGeneratorparam - the parameters to be used for key generationpublic byte[] generateKey()
k[0] ... k[15], r[0] ... r[15] with the required bits in r cleared
as per clamp(byte[]).generateKey in class CipherKeyGeneratorpublic static void clamp(byte[] key)
r (second 16 bytes) portion of the key.key - a 32 byte key value k[0] ... k[15], r[0] ... r[15]public static void checkKey(byte[] key)
k[0] ... k[15], r[0] ... r[15] with the required bits in r cleared
as per clamp(byte[]).java.lang.IllegalArgumentException - if the key is of the wrong length, or has invalid bits set
in the r portion of the key.