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Class semper.statement.StatementFile

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

public class StatementFile

extends Statement

Version:

$Revision: 1.3 $ $Date: 1998/07/17 09:13:00 $

Author:

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

See Also:

CryptoMan, Statement

StatementFile()

Creates a new, empty StatementFile object.

StatementFile(String)

Creates a StatementFile object with a reference to a file.

copyFrom(StatementFile)

Copy the contents of a StatementFile object to this one.

decipher(CryptoKeyInfo)

Decipher the statement.

decipher(String, CryptoKeyInfo)

Decipher an encrypted file and the statement.

encipher(String, CryptoKeyInfo)

Encipher the file and the statement using a conventional crypto system.

generateMAC(CryptoKeyInfo, MACAlgorithm)

Generate a (keyed) MAC value on a file.

generateSignature(CryptoKeyInfo, HashingAlgorithm, Certificate)

Sign a file.

getPlainText()

Returns the file in the StatementFile object.

getPrevious()

If a given StatementFile is obtained by making an operation on a StatementFile (sign, MAC) then this method can be used to retrieve that previous StatementFile.

pkDecipher(String, CryptoKeyInfo)

Decipher a pkEnciphered file and the statement object.

pkEncipher(String, CryptoKeyInfo, ConventionalAlgorithm, KeyPadding)

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

printContents()

Temporary function printing the file name and securityVal of a Statement.

setPlainFile(String)

Sets the file in the StatementFile.

statementFromBytes(byte[])

Convert byte array into a StatementFile object.

statementToBytes()

"Helper" method to linearize the statement into an array of bytes.

verifyMAC(CryptoKeyInfo)

Verify a (keyed) MAC value on a file.

verifySignature(CryptoKeyInfo)

Verify the signature in a signed file.

 public StatementFile()

Creates a new, empty StatementFile object. This method is intended to for use by the recipient of a linearized statement, who will make an empty statement and initialise its contents from a stream.

 public StatementFile(String newFileName)

Creates a StatementFile object with a reference to a file.

Parameters:

newFileName - the file name.

 public Object getPlainText()

Returns the file in the StatementFile object.

Returns:

the file to which the StatementFile object refers to.

Overrides:

getPlainText in class Statement

 public void setPlainFile(String filename)

Sets the file in the StatementFile.

Parameters:

the - file name to which the StatementFile will refer to.

 public Statement getPrevious() throws StatementManException

If a given StatementFile is obtained by making an operation on a StatementFile (sign, MAC) then this method can be used to retrieve that previous StatementFile. if a StatementFile has not been operated on or the last operation was encryption, then it is not possible to go back.

Returns:

the StatementFile from which the current was obtained

Throws: StatementManException

if it is not possible to retrieve the last StatementFile

Overrides:

getPrevious in class Statement

 public void encipher(String destFileName,
                      CryptoKeyInfo newKeyInfo) throws StatementManException

Encipher the file and the statement using a conventional crypto system. Encrypt the file that the Statement refers to. Linearise 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:

destFileName - identifies the name of the destination file that will store the encrypted information

newKeyInfo - identifies the key under which to encipher

Throws: StatementManException

if the statement could not be enciphered

See Also:

decipher, encipher, CryptoConstants

 public void decipher(String destFileName,
                      CryptoKeyInfo convKeyInfo) throws StatementManException

Decipher an encrypted file and the 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 is deciphered, and the resulting string is delinearized into the statement.

Parameters:

destFileName - identifies the name of the destination file that will store the decrypted information

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

Throws: StatementManException

if the statement could not be deciphered

See Also:

encipher, decipher

 public void decipher(CryptoKeyInfo convKeyInfo) throws StatementManException

Decipher the 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 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)

Throws: StatementManException

if the statement could not be deciphered

Overrides:

decipher in class Statement

See Also:

encipher, decipher

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

Sign a file. Hashes the file using the hash algorithm given as input parameter. The hash algorithm used is added to the file's hash value and the result is signed. A signature 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 and the signature.

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.

Throws: StatementManException

if signature generation failed

Overrides:

generateSignature in class Statement

See Also:

verifySignature

 public boolean verifySignature(CryptoKeyInfo trustedPublicKey) throws StatementManException

Verify the signature in a signed file. This method DOES NOT alter the Statement. To obtain the Statement, which was originally signed, use getPrevious().

Parameters:

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

Returns:

true if the signture is valid with respect to the given key.

Throws: StatementManException

if something went wrong during the verification

Overrides:

verifySignature in class Statement

See Also:

generateSignature, getPrevious

 public void generateMAC(CryptoKeyInfo newKeyInfo,
                         MACAlgorithm MACalg) throws StatementManException

Generate a (keyed) MAC value on a file. Generate a MAC value on the file. The MAC algorithm used is added and the MAC value of the result is stored in securityVal.

Parameters:

newKeyInfo - the key to use during the MAC operation

MACalg - describes the MAC algorithm to be used

Throws: StatementManException

if the MAC value could not be generated

Overrides:

generateMAC in class Statement

See Also:

verifyMAC, generateMAC

 public boolean verifyMAC(CryptoKeyInfo newKeyInfo) throws StatementManException

Verify a (keyed) MAC value on a file. Retrieve the MAC key using the keyInfo attribute and verify the MAC using this key. The statement is NOT CHANGED during verification. To get the Statement which was originally authenticated, use getPrevious().

Parameters:

newKeyInfo - the key to verify MAC with

Returns:

true if the MAC value is correct with respect to the key.

Throws: StatementManException

if the MAC could not be verified

Overrides:

verifyMAC in class Statement

See Also:

generateMAC, getPrevious

 public void pkEncipher(String destFileName,
                        CryptoKeyInfo newKeyInfo,
                        ConventionalAlgorithm convAlg,
                        KeyPadding keyEncryption) throws StatementManException

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

Parameters:

destFileName - identifies the name of the destination file that will store the encrypted information

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

Throws: StatementManException

if the encryption fails

See Also:

encipher, pkDecipher

 public void pkDecipher(String destFileName,
                        CryptoKeyInfo secretKey) throws StatementManException

Decipher a pkEnciphered file and the 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:

destFileName - identifies the name of the destination file that will store the decrypted information

newKeyInfo - is the key to be used for decryption

Throws: StatementManException

if the statement could not be deciphered

See Also:

pkEncipher, decipher

 public byte[] statementToBytes() throws StatementManException

"Helper" method to linearize the statement into an array of bytes.

Returns:

byte array containing the linearized statement.

Throws: StatementManException

if the statement could not be linearised.

 public void statementFromBytes(byte _byteArray[]) throws StatementManException

Convert byte array into a StatementFile object.

Throws: StatementManException

if conversion fails.

 public void copyFrom(StatementFile src)

Copy the contents of a StatementFile object to this one.

Throws: StatementManException

if conversion fails.

 public void printContents()

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

Overrides:

printContents in class Statement

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