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Bouncy Castle Cryptography 1.50 | ||||||||
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java.lang.Objectorg.bouncycastle.crypto.CipherKeyGenerator
org.bouncycastle.crypto.generators.Poly1305KeyGenerator
public class Poly1305KeyGenerator
Generates keys for the Poly1305 MAC.
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.
Poly1305
Field Summary |
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Fields inherited from class org.bouncycastle.crypto.CipherKeyGenerator |
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random, strength |
Constructor Summary | |
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Poly1305KeyGenerator()
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Method Summary | |
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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. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public Poly1305KeyGenerator()
Method Detail |
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public void init(KeyGenerationParameters param)
init
in class CipherKeyGenerator
param
- 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 CipherKeyGenerator
public static void clamp(byte[] key)
r
(second 16 bytes) portion of the 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.
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