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Class semper.statement.Statement

java.lang.Object
   |
   +----semper.statement.Statement

public class Statement

extends Object

implements StatementConstants, Streamable, CryptoConstants

Version:

$Revision: 1.32 $ $Date: 1997/04/17 10:55:22 $

Author:

Jesper Drud Nielsen ([email protected]), Torben Pryds Pedersen ([email protected])

See Also:

CryptoMan

Statement()

Creates a new, empty Statement object.

Statement(byte[], String, String)

Creates a new Statement object containing message, senderID and RecipientId.

Statement(Streamable, String, String)

Creates a new Statement object containing message, senderID and RecipientId.

Statement(String, String, String)

Creates a new Statement object containing message, senderID and RecipientId.

decipher(CryptoKeyInfo)

Decipher an encrypted statement.

encipher(CryptoKeyInfo)

Encipher a statement using a conventional crypto system.

generateMAC(CryptoKeyInfo, Date, int)

Generate a (keyed) MAC value on a statement object.

generateSignature(CryptoKeyInfo, int, Certificate)

Sign a statement.

getAlg()

Returns the cryptographic algorithm used in the Statement.

getDate()

Get the date.

getPlainStreamable()

Returns the message in the Statement as a Streamable provided the Statement is a plaintext and it was constructed using a Streamable.

getPlainString()

Returns the message in the Statement as a String provided the Statement was constructed using a String, which is either in plain, has been signed or a MAC value has been appended.

getPlaintext()

Returns the message in the Statement provided it is a plaintext.

getRecipient()

Get the information �contained in the Statement about the recipient.

getSender()

Get the information �contained in the Statement about the sender.

myStreamSize()

Returns the size of the Statement object when externalized.

pkDecipher(CryptoKeyInfo)

Decipher a pkEnciphered statement object.

pkEncipher(CryptoKeyInfo, int, int)

Encipher a statement object under a random, conventional key using encipher, and include this key enciphered under a public key.

printContents()

Temporary function printing the message and securityVal of a Statement.

readObject(StreamInputInterface)

Internalizes a Statement object.

setDate(Date)

Set the date.

setRecipient(String)

Inserts identification of the recipient in Statement.

setSender(String)

Inserts identification of the sender in Statement.

verifyMAC(Date, Date, CryptoKeyInfo)

Verify a (keyed) MAC value on a statement object.

verifySignature(Date, Date, CryptoKeyInfo)

Verify the signature in a signed statement.

writeObject(StreamOutputInterface)

Externalizes a Statement object.

  public Statement()

Creates a new, empty Statement object. A new Statement object is created. All of its attributes are empty, except that its message_type attribute indicates that the Statement is empty. This method is intended to for use by the reipient of a linearized statement, who will make an empty statement and initialise its contents from a stream.

  public Statement(byte newMessage[],
                   String newSenderId,
                   String newRecipientId)

Creates a new Statement object containing message, senderID and RecipientId. A new Statement object containing a given plaintext and having a sender identification and recipient identification.

Parameters:

newMessage - The plaintext message to insert in the Statement

newSenderId - The sender identification

newRecipientId - The recipient identification

  public Statement(String newMessage,
                   String newSenderId,
                   String newRecipientId)

Creates a new Statement object containing message, senderID and RecipientId. A new Statement object containing a given plaintext and having a sender identification and recipient identification. The message is stored as an array of bytes.

Parameters:

newMessage - The plaintext message as a String to insert in the Statement

newSenderId - The sender identification

newRecipientId - The recipient identification

  public Statement(Streamable newMessage,
                   String newSenderId,
                   String newRecipientId) throws StatementManException

Creates a new Statement object containing message, senderID and RecipientId. A new Statement object containing a given plaintext and having a sender identification and recipient identification. The message is stored as an array of bytes.

Parameters:

newMessage - The plaintext message as a Streamable object to insert in the Statement

newSenderId - The sender identification

newRecipientId - The recipient identification

Throws: StatementManException

if the new message could not be serialised

  public byte[] getPlaintext() throws StatementManException

Returns the message in the Statement provided it is a plaintext. This method only makes sense if the Statement is constructed using anarray of bytes, since otherwise the result of this operation returns an array of bytes which depends on the actual implementation.

Returns:

the array of butes contained in the plaintext

Throws: StatementManException

if the statement is not a plaintext or the message is not an array of bytes.

  public String getPlainString() throws StatementManException

Returns the message in the Statement as a String provided the Statement was constructed using a String, which is either in plain, has been signed or a MAC value has been appended.

Returns:

A String corresponding to the message in the statement

Throws: StatementManException

if the statement is encrypted or does not contain a String message

  public Streamable getPlainStreamable() throws StatementManException

Returns the message in the Statement as a Streamable provided the Statement is a plaintext and it was constructed using a Streamable.

Returns:

A Streamable corresponding to the message in the statement

Throws: StatementManException

if the statement is not a plaintext or the Statement was not initially constructed with a Streamable

  public int encipher(CryptoKeyInfo newKeyInfo) throws StatementManException

Encipher a statement using a conventional crypto system. Linearises the statement and encrypts it under the key in or designated by newKeyInfo. During this process the Statement is changed in that the message and (if present) the date, sender identification and recipient identification are removed. Instead the Statement contains the ciphertext.

Parameters:

newKeyInfo - identifies the key under which to encipher

Returns:

0 on succes

Throws: StatementManException

if the statement could not be enciphered

See Also:

decipher, CryptoConstants

  public int decipher(CryptoKeyInfo convKeyInfo) throws StatementManException

Decipher an encrypted statement. If a decipher key is provided in convKeyInfo, it is used to decipher. Otherwise, a decipher key is derived from the statement objects keyInfo attribute. The ciphertext in the statement (in the securityVal attribute) is deciphered, and the resulting string is delinearized into the statement.

Parameters:

The - key needed for decryption (if null the key information from the Statement is used)

Returns:

0 on success

Throws: StatementManException

if the statement could not be deciphered

See Also:

encipher

  public void generateSignature(CryptoKeyInfo newKeyInfo,
                                int hashAlg,
                                Certificate newCertificate) throws StatementManException

Sign a statement. Writes a timestamp in the Statement, linearises it and hashes it using the ahsh function given as input parameter. A signature on the hash value is generated using the key in newKeyInfo. Afterwards the statement contains the linearised statement (before hashing), identification of the key (a certificate on the public key if supplied as input) used to sign, the signature and possible originator and recipient information if this was in the Statement initially.

Parameters:

newKeyInfo - the secret signature key

hashAlg - designates the hashing algorithm to be used (if a DSA signature is used SHS-1 will be used, overwriting ths parameter)

newCertificate - is the certificate to be added to the statement.

Returns:

0 on success, otherwise an erro code

Throws: StatementManException

if signature generation failed

See Also:

verifySignature

  public int verifySignature(Date timewindowstart,
                             Date timewindowend,
                             CryptoKeyInfo trustedPublicKey) throws StatementManException

Verify the signature in a signed statement. Verifies the signature in securityVal against the message. After verification, the contents of message is delinearized into the statement. Thus this method changes the Statement!

Parameters:

timewindowstart - the earliest signature date to accept

timewindowend - the lates signature date to accept

trustedPublicKey - is used to verify the signature. If no key is supplied the public key in the certificate is used.

Returns:

RC_OK if the signature is valid, RC_INVALIDCERTIFICATE if the an invalid certificate (!= null) is in the Statement, RC_INVSTATEMENTOP if the Statement is not signed, RC_NOPUBLICKEY if no public key is available (neither in certificate nor a trusted public key) and RC_SIGNATURENOTBORN and RC_SIGNATURETOOOLD if the signature is too old or too new, respectively.

Throws: StatementManException

if something went wrong during the verification

See Also:

generateSignature

  public int generateMAC(CryptoKeyInfo newKeyInfo,
                         Date newdate,
                         int MACalg) throws StatementManException

Generate a (keyed) MAC value on a statement object. Linearize the statement into the message attribute. Generate a MAC value and write it in securityVal. Information about the used key is stored in the resulting Statement.

Parameters:

newKeyInfo - the key to use during the MAC operation

newdate - is a timestamp of the operation

MACalg - describes the MAC algorithm to be used

Returns:

0 on success

Throws: StatementManException

if the MAC value could not be generated

See Also:

verifyMAC

  public int verifyMAC(Date timewindowstart,
                       Date timewindowend,
                       CryptoKeyInfo newKeyInfo) throws StatementManException

Verify a (keyed) MAC value on a statement object. Retrieve the MAC key using the keyInfo attribute and verify the MAC using this key. The statement on which the MAC was generated is delinearized into the statement.

Returns:

0 on success

Throws: StatementManException

if the MAC could not be verified

See Also:

generateMAC

  public int pkEncipher(CryptoKeyInfo newKeyInfo,
                        int convAlg,
                        int keyEncryption) throws StatementManException

Encipher a statement object under a random, conventional key using encipher, and include this key enciphered under a public key.

Parameters:

newKeyInfo - is the public key to be used for encryption

convAlg - the conventional algorithm to be used (0 indicates no conventional encryption)

keyEncryption - describes the way the conventional key is encrypted

Returns:

0

Throws: StatementManException

if the encryption fails

See Also:

encipher, pkDecipher

  public int pkDecipher(CryptoKeyInfo secretKey) throws StatementManException

Decipher a pkEnciphered statement object. The enciphered conventinal key is deciphered using the secret key supplied secret (asymmetric) key. The resulting conventional key is used to decipher the statement using decipher.

Parameters:

newKeyInfo - is the key to be used for decryption

Returns:

returncode (0 for success)

Throws: StatementManException

if the statement could not be deciphered

See Also:

pkEncipher, decipher

  public void setDate(Date newDate)

Set the date. This function can be used to put a timestamp in a statement.

Parameters:

newDate - is the Date to be set in a Statement

  public Date getDate()

Get the date.

Returns:

time stamp in the statement (null if there is no time stamp)

  public int getAlg()

Returns the cryptographic algorithm used in the Statement. In case more operations have been done the last one is returned.

Returns:

an integer describing the algorithm used to protect the statement (if the statement is not protected 0 is returned)

  public void setSender(String sender)

Inserts identification of the sender in Statement. A null string clears all information about the sender.

Parameters:

sender - identifies the sender

See Also:

getSender

  public String getSender()

Get the information �contained in the Statement about the sender. A null string means that the statement contains no information about the sender.

Returns:

the sender identification

See Also:

setSender

  public void setRecipient(String recipient)

Inserts identification of the recipient in Statement. A null string clears all information about the recipient.

Parameters:

the - recipient identification

See Also:

getRecipient

  public String getRecipient()

Get the information �contained in the Statement about the recipient. A null string means that the statement contains no information about the recipient.

Returns:

the recipient identification

See Also:

setRecipient

  public void writeObject(StreamOutputInterface s) throws StreamIOException

Externalizes a Statement object. By calling this method a Statement will be written to the IO stream.

Returns:

no return value

Throws: StreamIOException

if linearisation fails

  public void readObject(StreamInputInterface s) throws StreamIOException

Internalizes a Statement object. By calling this method a Statement will be read from the IO stream.

Returns:

no return value

Throws: IOException

If the input data is corrupt.

  public int myStreamSize() throws StreamIOException

Returns the size of the Statement object when externalized.

Returns:

Size of externalized object

Throws: IOException

if the correct sixe could not be computed.

  public void printContents()

Temporary function printing the message and securityVal of a Statement. This function is only supplied for testing.

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