Java Card API

keypair

2017-05-22 16:52:55 M&W SmartCard 2

javacard.security

Class KeyPair


public final class KeyPairextends Object

This class is a container for a key pair (a public key and a private key). It does not enforce any security, and, when initialized, should be treated like a PrivateKey. In addition, this class features a key generation method.

See Also:PublicKey ,PrivateKey


Field Summary
static byte ALG_DSA           KeyPair object containing a DSA key pair.
static byte ALG_EC_F2M           KeyPair object containing an EC key pair for EC operations over fields of characteristic 2 with polynomial basis.
static byte ALG_EC_FP           KeyPair object containing an EC key pair for EC operations over large prime fields
static byte ALG_RSA           KeyPair object containing a RSA key pair.
static byte ALG_RSA_CRT           KeyPair object containing a RSA key pair with private key in its Chinese Remainder Theorem form.

 

Constructor Summary
KeyPair (byte algorithm,short keyLength)          Constructs a KeyPair instance for the specified algorithm and keylength;the encapsulated keys are uninitialized.
KeyPair (PublicKey  publicKey,PrivateKey  privateKey)          Constructs a new KeyPair object containing the specifiedpublic key and private key.

 

Method Summary
 void genKeyPair ()          (Re)Initializes the key objects encapsulated in this KeyPair instancewith new key values.
 PrivateKey getPrivate ()          Returns a reference to the private key component of this KeyPair object.
 PublicKey getPublic ()          Returns a reference to the public key component of this KeyPair object.

 

Methods inherited from class java.lang.Object
equals

 

Field Detail

ALG_RSA

public static final byte ALG_RSA

KeyPair object containing a RSA key pair.

See Also:Constant Field Values


ALG_RSA_CRT

public static final byte ALG_RSA_CRT

KeyPair object containing a RSA key pair with private key in its Chinese Remainder Theorem form.

See Also:Constant Field Values


ALG_DSA

public static final byte ALG_DSA

KeyPair object containing a DSA key pair.

See Also:Constant Field Values


ALG_EC_F2M

public static final byte ALG_EC_F2M

KeyPair object containing an EC key pair for EC operations over fields of characteristic 2 with polynomial basis.

See Also:Constant Field Values


ALG_EC_FP

public static final byte ALG_EC_FP

KeyPair object containing an EC key pair for EC operations over large prime fields

See Also:Constant Field Values

Constructor Detail

KeyPair

public KeyPair(byte algorithm, short keyLength) throws CryptoException

Constructs a KeyPair instance for the specified algorithm and keylength;the encapsulated keys are uninitialized. To initialize the KeyPair instance use thegenKeyPair() method. The encapsulated key objects are of the specified keyLength size and implement the appropriate Keyinterface associated with the specified algorithm (example - RSAPublicKey interface for the public key andRSAPrivateKey interface for the private key within an ALG_RSA key pair). Notes:

  • The key objects encapsulated in the generated KeyPair object need not support the KeyEncryption interface.


Parameters:algorithm - the type of algorithm whose key pair needs to be generated. Valid codes listed in ALG_* constants above. See ALG_RSA .

keyLength - the key size in bits. The valid key bit lengths are key type dependent. See the KeyBuilder class.

Throws: CryptoException- with the following reason codes:

  • CryptoException.NO_SUCH_ALGORITHM if the requested algorithm associated with the specified type, size of key is not supported.


See Also:KeyBuilder ,Signature ,javacardx.crypto.Cipher ,javacardx.crypto.KeyEncryption


KeyPair

public KeyPair(PublicKey  publicKey, PrivateKey  privateKey) throws CryptoException

Constructs a new KeyPair object containing the specifiedpublic key and private key.

Note that this constructor only stores references to the public and private key components in the generated KeyPair object. It does not throw an exception if the key parameter objects are uninitialized.

Parameters:publicKey - the public key.

privateKey - the private key.

Throws: CryptoException- with the following reason codes:

  • CryptoException.ILLEGAL_VALUE if the input parameter key objects are mismatched - different algorithms or different key sizes. Parameter values are not checked.


  • CryptoException.NO_SUCH_ALGORITHM if the algorithm associated with the specified type, size of key is not supported.


Method Detail

genKeyPair

public final void genKeyPair() throws CryptoException

(Re)Initializes the key objects encapsulated in this KeyPair instancewith new key values. The initialized public and private key objects encapsulated in this instance will then be suitable for use with the Signature, Cipher and KeyAgreement objects.An internal secure random number generator is used during new key pair generation. Notes:

  • For the RSA algorithm, if the exponent value in the public key object is pre-initialized, it will be retained. Otherwise, a default value of 65537 will be used.


  • For the DSA algorithm, if the p, q and g parameters of the public key object are pre-initialized, they will be retained. Otherwise, default precomputed parameter sets will be used. The requireddefault precomputed values are listed in Appendix B of Java Cryptography ArchitectureAPISpecification&Reference document.


  • For the EC case, if the Field, A, B, G and R parameters of the public key object are pre-initialized, then they will be retained. Otherwise default pre-specified values MAY be used (e.g. WAP predefined curves), since computation of random generic EC keys is infeasible on the smart card platform.


  • If the time taken to generate the key values is excessive, the implementation may automatically request additional APDU processing time from the CAD.


Throws: CryptoException- with the following reason codes:

  • CryptoException.ILLEGAL_VALUE if the pre-initialized exponentvalue parameter in the RSA public key or the pre-initialized p, q, g parameter set in theDSA public key or the pre-initialized Field, A, B, G and R parameter set in public EC keyis invalid.


See Also:javacard.framework.APDU ,Signature ,javacardx.crypto.Cipher ,RSAPublicKey ,ECKey ,DSAKey


getPublic

public PublicKeygetPublic()

Returns a reference to the public key component of this KeyPair object.

Returns:a reference to the public key.


getPrivate

public PrivateKeygetPrivate()

Returns a reference to the private key component of this KeyPair object.

Returns:a reference to the private key. 


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