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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: 1.24 $ $Date: 1996/09/19 11:28:17 $

Author:

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

See Also:

Statement

Statement()

Creates a new, empty Statement object.

Statement(byte[], String, String)

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

decipher(CryptoKeyInfo)

Decipher a ciphered statement.

encipher(CryptoKeyInfo)

Encipher a statement.

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.

getPlainString()

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

getPlaintext()

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

getRecipient()

Get the recipient.

getSender()

Get 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, and include this key enciphered under a public RSA 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)

Set the recipient.

setSender(String)

Set the sender.

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 internalize 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 byte[] getPlaintext() throws StatementManException

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

Returns:

the message contained in the plaintext

Throws: StatementManException

if the statement is not a plaintext

  public String getPlainString() throws StatementManException

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

Returns:

A String corresponding to the message in the statement

Throws: StatementManException

if the statement is not a plaintext

  public int encipher(CryptoKeyInfo newKeyInfo) throws StatementManException

Encipher a statement. Linearises the statement and encrypts it under the key in or designated by newKeyInfo. Afterwards, the enciphered message is deleted and the ciphertext is put in securityVal. The date, senderId and recipientId attributes as well as the actual key value are cleared.

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 a ciphered 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 securityVal attribute which contains the enciphered statement 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 the current date and time in the date attribute ob the object and linearises it. A signature is generated using the key in newKeyInfo. Afterwards the linearized message is in message and the signature is put in securityVal. The newKeyInfo is put into the keyInfo field.

Parameters:

newKeyInfo - the secret signature key

hashAlg - designatures the hashing algorithm to be used

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

Returns:

0 on success

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.

Parameters:

timewindowstart - the earliest signature date to accept

timewindowend - the lates signature date to accept

trustedPublicKey - is the key against which the certificate should be verified

Returns:

0 if the signature is valid. 1 if it is not valid

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. The newKeyInfo is stored in the keyInfo attribute.

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, and include this key enciphered under a public RSA 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:

pkDecipher

  public int pkDecipher(CryptoKeyInfo secretKey) throws StatementManException

Decipher a pkEnciphered statement object.

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

  public void setDate(Date newDate)

Set the date.

Parameters:

newDate - is the Date to be set in a Statement

  public Date getDate()

Get the date.

Returns:

the date value of the statement

  public int getAlg()

Returns the cryptographic algorithm used in the Statement. long description with pre/post-conditions etc follows here

Returns:

an integer describing the algorithm used

  public void setSender(String sender)

Set the sender. The senderId attribute is set to a specified string. A null string clears the sender.

Parameters:

the - sender identification

See Also:

getSender

  public String getSender()

Get the sender. The senderId attribute is returned as a string. A null string means "no sender".

Returns:

the sender identification

See Also:

setSender

  public void setRecipient(String recipient)

Set the recipient. The recipientId attribute is set to a specified string. A null string clears the recipient.

Parameters:

the - recipient identification

See Also:

getRecipient

  public String getRecipient()

Get the recipient. The recipientId attribute is returned as a string. A null string means "no 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

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