public class DSAPrivateKey extends PrivateKeyInfo implements java.security.interfaces.DSAPrivateKey, java.io.Serializable
This class extends iaik.pkcs.pkcs8.PrivateKeyInfo for supporting the
PKCS#8 Private Key Information Standard for the DSA private keys. This class
implements the java.security.interfaces.DSAPrivateKey interface for
providing the functionality of a private key used for signing some data within
the DSA algorithm.
The Digital Signature Algorithm (DSA) only can be used for digital signing (respectively signature verifying). It cannot be used for data encryption.
The DSA algorithm uses a certain number of parameters:
p, which length is a multiple of 64 bits lying
between 512 and 1024 bits
q) of p-1
(h(p-1)/q)(mod p) > 1
g = (h(p-1)/q)(mod p)
x less than q
y calculated from y = (gx)(mod p)
An application wishing to create a DSAPrivateKey to be used for data signing with the
DSA algorithm, uses a proper getInstance method of the
java.security.KeyPairGenerator class, which subsequently maybe casted to
DSAKeyPairGenerator for performing an algorithm-specific initialization with
proper DSA parameters. If an algorithm-specific initialization is not required, the cast
to DSAKeyPairGenerator can be omitted.
Generally four steps have to be performed for creating a DSAPrivateKey by using a proper KeyPairGenerator:
KeyPairGenerator has to be instantiated thereby specifying
the application's intention to create keys for use within the DSA algorithm:
KeyPairGenerator key_gen = KeyPairGenerator.getInstance("DSA", "IAIK");
initialize method. For initializing the generator to create keys with
a modulus length of, e.g., 1024 bits, this can be explicitly specified (1024 bits also
is the default value for the modulus length when not explicitly initializing the
generator):
key_gen.initialize(1024);
generateKeyPair():
KeyPair key_pair = key_gen.generateKeyPair();
DSAPrivateKey dsa_priv_key = (DSAPrivateKey)key_pair.getPrivate();
For performing an algorithm-specific initialization with particular DSA parameters
(which may be an instance of DSAParams representing the public parameter
values p, q and g), an explicit cast of the
KeyPairGenerator will be necessary for obtaining a specific DSAKeyPairGenerator to
be initialized with the desired DSA parameters:
DSAKeyPairGenerator dsa_key_gen = (DSAKeyPairGenerator)key_gen; dsa_key_gen.initialize(dsa_params, random);
(where random denotes some random seed)
Guidelines on how to create some key using a KeyPairGenerator can be found in http://java.sun.com/products/JDK/1.1/docs/guide/security/CryptoSpec.html.
PrivateKeyInfo,
DSAPrivateKey,
KeyPairGenerator,
KeyPair,
DSAPublicKey,
DSAKeyPairGenerator,
DSAKeyFactory,
DSAParams,
Serialized Formprivate_key_algorithm, private_key_info| Constructor and Description |
|---|
DSAPrivateKey(ASN1Object obj)
Creates a new DSAPrivateKey from the given ASN.1 object.
|
DSAPrivateKey(java.math.BigInteger x,
java.math.BigInteger p,
java.math.BigInteger q,
java.math.BigInteger g)
Creates a new DSAPrivateKey from the given BigInteger values.
|
DSAPrivateKey(java.math.BigInteger x,
java.security.interfaces.DSAParams dsaParams)
Creates a new DSAPrivateKey from given private key value x and DSA parameters
|
DSAPrivateKey(byte[] key)
Creates a new DSAPrivateKey from the given DER encoded byte array.
|
DSAPrivateKey(java.security.interfaces.DSAPrivateKey privKey)
Creates a new DSAPrivateKey from the given DSAPrivateKey.
|
DSAPrivateKey(java.security.spec.DSAPrivateKeySpec keySpec)
Creates a new DSAPrivateKey from the given DSAPrivateKeySpec representing
the DSA private key value x, and the public values p, q and g.
|
DSAPrivateKey(java.io.InputStream is)
Creates a new DSAPrivateKey from an InputStream.
|
| Modifier and Type | Method and Description |
|---|---|
protected void |
decode(byte[] privateKey)
Decodes a DER encoded DSA private key.
|
protected byte[] |
encode()
Returns this DSA private key as DER encoded byte array.
|
boolean |
equals(java.lang.Object obj)
Compares this DSAPrivateKey with the given DSAPrivateKey.
|
java.lang.String |
getAlgorithm()
Returns the name of the appertaining algorithm.
|
java.security.interfaces.DSAParams |
getParams()
Returns the DSA parameters prime p, sub-prime q and base g as DSAParams.
|
java.math.BigInteger |
getX()
Returns the private key value x.
|
int |
hashCode()
Returns a hash code for this DSAPrivateKey object.
|
java.lang.String |
toString()
Returns a string that represents the contents of this private key.
|
createPrivateKeyInfo, decode, getEncoded, getFormat, getPrivateKey, getPrivateKey, toASN1Object, writeTopublic DSAPrivateKey(java.math.BigInteger x,
java.security.interfaces.DSAParams dsaParams)
x - the BigInteger value representing the DSA private key valuedsaParams - the public DSA parameters p (prime), q (sub-prime) and g (base) as DSAParamsDSAParamspublic DSAPrivateKey(java.math.BigInteger x,
java.math.BigInteger p,
java.math.BigInteger q,
java.math.BigInteger g)
x - the BigInteger value representing the DSA private keyp - the public prime p (of a multiple length of 64 bits between 512 and 1024 bits)q - the public sub-prime q (a 160-bit prime factor of p-1)g - the public base g (=(h(p-1)/q)(mod p) > 1, with h < p-1)public DSAPrivateKey(java.security.spec.DSAPrivateKeySpec keySpec)
keySpec - the DSAPrivateKeySpec representing the private key value x,
the prime p, the sub-prime q, and the base gDSAPrivateKeySpecpublic DSAPrivateKey(java.security.interfaces.DSAPrivateKey privKey)
privKey - the DSAPrivateKeypublic DSAPrivateKey(byte[] key)
throws java.security.InvalidKeyException
key - the byte array holding the DER encoded private key ASN.1 data structurejava.security.InvalidKeyException - if something is wrong with the encoding of the keypublic DSAPrivateKey(ASN1Object obj) throws java.security.InvalidKeyException
PrivateKeyInfo holding the DSA private key.obj - the private key ASN.1 data structurejava.security.InvalidKeyException - if something is wrong with the key encodingpublic DSAPrivateKey(java.io.InputStream is)
throws java.security.InvalidKeyException,
java.io.IOException
This constructor may be used for parsing an already exisiting
DSA private key, wrapped into a PKCS#8 PrivateKeyInfo that is supplied as DER encoded byte array.
is - the input stream with the data to be read to initialize the private keyjava.security.InvalidKeyException - if something is wrong with the key encodingjava.io.IOException - if an I/O error occurspublic java.math.BigInteger getX()
getX in interface java.security.interfaces.DSAPrivateKeypublic java.security.interfaces.DSAParams getParams()
getParams in interface java.security.interfaces.DSAKeyprotected byte[] encode()
This method is protected and typically will not be used by an application. Rather
it is used by the parent PKCS#8 PrivateKeyInfo class for encoding the inherent DSA private key.
encode in class PrivateKeyInfoprotected void decode(byte[] privateKey)
throws java.security.InvalidKeyException
This method is protected and typically will not be used by an application. Rather
it is used by the parent PKCS#8 PrivateKeyInfo class for decoding the inherent DSA private key.
decode in class PrivateKeyInfoprivateKey - the DSA private key as DER encoded byte arrayjava.security.InvalidKeyException - if the given key is not a DSA private keypublic java.lang.String getAlgorithm()
getAlgorithm in interface java.security.KeygetAlgorithm in class PrivateKeyInfopublic int hashCode()
hashCode in class java.lang.Objectpublic boolean equals(java.lang.Object obj)
equals in class PrivateKeyInfoobj - the other DSAPrivateKeytrue, if the two private key objects are equal, false otherwisepublic java.lang.String toString()
toString in class PrivateKeyInfo