ds.ov2.front
Class PTLS_rsa_parameters

java.lang.Object
  ds.ov2.front.PTLS_rsa_parameters

public class PTLS_rsa_parameters
extends Object

PTLS parameters. The PTLS parameters are the static parameters that are needed for the OV-chip RSA protocols. They need to be generated once before the system starts. The PTLS parameter set contains the key material as well as the number of attributes and the key length'.

Montgomerization and Demontgomerization factors depend on the RSA modulus n and they are therefore included here (in the host modulus hmod). However, they also depend on the number of Montgomery digits and therefore on the applet type. Some methods here take therefore an applet type argument, although the PTLS parameters itself are independent of the applet type.

CPP Preprocessing

This class uses the following cpp defines: APPLET_TESTFRAME, TESTFRAME

Execution Environment:

host

Author:

Hendrik Tews

Version:

$Revision: 1.22 $

Last Commit:

$Date: 2010-02-16 10:26:07 $ by $Author: tews $

Nested Class Summary

static class

PTLS_rsa_parameters.PTLS_io_exception Exception for I/O problems during reading/writing PTLS parameters from/to disk.

Field Summary

int	attribute_number The number of attributes.
BigInteger[]	base The array of the bases.
int	base_length Length of the bases and the RSA modulus in bits (long bignats).
int	exponent_length The length of the attributes in bits (short or exponent bignats).
Host_modulus	hmod The RSA modulus wrapped in a host modulus that contains (de-)montgomerization factors as well.
(package private) BigInteger	inv_v 1/v, the inverse of v modulus euler_phi(n)
BigInteger	n The RSA modulus, product of two primes.
private PrintWriter	out Output channel for debug and progress messages.
static int	prime_certainy Prime certainy: certainy parameter for probabilistic prime generation.
private BigInteger	ptls_private_key The private key x of the PTLS.
BigInteger	ptls_public_key The public key of the PTLS h = x^v.
private Random	rand Randomness source.
BigInteger	v The RSA exponent v, coprime to euler_phi(n).
private int	verbosity Verbosity level.
private static String	version cvs revision number, kept up to date by cvs keyword substitution.

Constructor Summary

PTLS_rsa_parameters(int attribute_number, PrintWriter out, int verbosity)
Constructor.

Method Summary

private BigInteger[]	generate_v(BigInteger p, BigInteger q) Generate the public RSA exponent v.
void	generate(int base_length, int exponent_length, Applet_type applet_type) Generate a new set of PTLS parameters and store them in this instance.
private static String	get_next_data(BufferedReader fin) Retrurn the part after the colon from the next line in the input fin.
int	make_base_bytes(int montgomery_digits) Compute the length of the bases and the RSA modulus in bytes for this instance.
int	make_exponent_bytes() Compute the length of the attributes/exponents in bytes for this instance.
(package private) void	print_all(Applet_type applet_type, PrintWriter out) Print all parameters in this instance to the given channel.
static PTLS_rsa_parameters	read_from_file(String filename, Applet_type applet_type, PrintWriter out, int verbosity) Create a new PTLS parameter instance by loading file filename.
void	write_to_file(String filename) Write the PTLS parameters in this instance to file filename.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

base_length

public int base_length

Length of the bases and the RSA modulus in bits (long bignats).

exponent_length

public int exponent_length

The length of the attributes in bits (short or exponent bignats).

attribute_number

public final int attribute_number

The number of attributes.

n

public BigInteger n

The RSA modulus, product of two primes.

hmod

public Host_modulus hmod

The RSA modulus wrapped in a host modulus that contains (de-)montgomerization factors as well.

v

public BigInteger v

The RSA exponent v, coprime to euler_phi(n). All attributes must be smaller than v.

inv_v

BigInteger inv_v

1/v, the inverse of v modulus euler_phi(n)

ptls_private_key

private BigInteger ptls_private_key

The private key x of the PTLS.

ptls_public_key

public BigInteger ptls_public_key

The public key of the PTLS h = x^v.

base

public BigInteger[] base

The array of the bases. Has length attribute_number.

prime_certainy

public static final int prime_certainy

Prime certainy: certainy parameter for probabilistic prime generation.

See Also:

Constant Field Values

rand

private final Random rand

Randomness source.

out

private PrintWriter out

Output channel for debug and progress messages.

verbosity

private int verbosity

Verbosity level.

version

private static final String version

cvs revision number, kept up to date by cvs keyword substitution. The revision number is used to tag PTLS parameter files.

See Also:

Constant Field Values

Constructor Detail

PTLS_rsa_parameters

public PTLS_rsa_parameters(int attribute_number,
                           PrintWriter out,
                           int verbosity)

Constructor. Copies only the arguments into the state of this instance. Does not generate new PTLS parameters.

Parameters:

attribute_number - number of attributes

out - debug/progress messages

verbosity - verbosity

Method Detail

generate_v

private BigInteger[] generate_v(BigInteger p,
                                BigInteger q)

Generate the public RSA exponent v. If compiled with APPLET_TESTFRAME and if another fixed input is available, take the next fixed input as v. Otherwise generate it randomly satisfying the necessary conditions.

Parameters:

p - first factor of the RSA modulus

q - second factor of the RSA modulus

Returns:

v of bit-length exponent_length, prime, and coprime to phi(p * q)

make_base_bytes

public int make_base_bytes(int montgomery_digits)

Compute the length of the bases and the RSA modulus in bytes for this instance.

Parameters:

montgomery_digits - number of montgomery digits

Returns:

base length in bytes

make_exponent_bytes

public int make_exponent_bytes()

Compute the length of the attributes/exponents in bytes for this instance.

Returns:

attribute/exponent length in bytes

generate

public void generate(int base_length,
                     int exponent_length,
                     Applet_type applet_type)
              throws NoSuchAlgorithmException

Generate a new set of PTLS parameters and store them in this instance. For base length greater than 512 bits the (hopefully secure) Java RSA key generator is used. For base length below 512 bits Unsecure_rsa_key is used.

If compiled with APPLET_TESTFRAME, and if fixed inputs are available, they are taken as follows. First two inputs: factors of the RSA modulus n. Input number 3: v. Input number 4: x, the private PTLS key ptls_private_key. The next attribute_number inputs: the bases.

Parameters:

base_length - length of the bases and the RSA modulus in bits

exponent_length - length of the attributes (exponents) in bits

applet_type - current applet type for determining the number of Montgomery digits and the (de-)montgomerization factors

Throws:

NoSuchAlgorithmException - if no provider for RSA key generation can be found

write_to_file

public void write_to_file(String filename)
                   throws PTLS_rsa_parameters.PTLS_io_exception

Write the PTLS parameters in this instance to file filename. No compatibility with future and past versions. The file format is simply ASCII with the numbers as decimal strings.

Parameters:

filename - file to write to

Throws:

PTLS_rsa_parameters.PTLS_io_exception - if an IO error occurs

get_next_data

private static String get_next_data(BufferedReader fin)
                             throws PTLS_rsa_parameters.PTLS_io_exception

Retrurn the part after the colon from the next line in the input fin.

Parameters:

fin - input reader

Returns:

the part after the colon of the next line, which should be a number in decimal base

Throws:

PTLS_rsa_parameters.PTLS_io_exception - for read errors

read_from_file

public static PTLS_rsa_parameters read_from_file(String filename,
                                                 Applet_type applet_type,
                                                 PrintWriter out,
                                                 int verbosity)
                                          throws PTLS_rsa_parameters.PTLS_io_exception

Create a new PTLS parameter instance by loading file filename.

Parameters:

filename - file to read

applet_type - current applet type for determining the number of Montgomery digits and the (de-)montgomerization factors

out - debug/progress channel, may be null to supress output

verbosity - verbosity level

Returns:

parameter instance with parameters read from filename

Throws:

PTLS_rsa_parameters.PTLS_io_exception - if the file is not accessable, its version tag does not match version, or some other read error occurs

print_all

void print_all(Applet_type applet_type,
               PrintWriter out)

Print all parameters in this instance to the given channel.

Only available if TESTFRAME is defined.

Parameters:

applet_type - current applet type for determining the number of Montgomery digits and the (de-)montgomerization factors

out - channel to print to