Public Member Functions | Private Attributes | List of all members
arithm::ModPGrp Class Reference

Implements a q-subgroup of a modular field. More...

#include <modpgrp.hpp>

+ Inheritance diagram for arithm::ModPGrp:
+ Collaboration diagram for arithm::ModPGrp:

Public Member Functions

 ModPGrp (mpz_class ord, mpz_class add, mpz_class gen, uint8_t encoding)
 Initializes a modular p-subgroup of order ord by building a new ModField instance of order add, setting it to be the baseGroup and using gen as a generator.
 ModPGrp (verifierUtils::ByteTree *bt)
 Parses a ByteTree to create a ModPGrp.
verifierUtils::ByteTree * toByteTree ()
 Returns the bytetree representation of this group.
ArrayOfElmts getRandArray (cryptoTools::PRG *prg, unsigned int nr, unsigned int n0)
 Returns an array of elements of size n0 derived using a prg.
- Public Member Functions inherited from arithm::PSubGroup
 PSubGroup (Group *bgrp, mpz_class order, mpz_class gen)
 Initializes a p-subgroup instance.
Elmt multiplication (Elmt e1, Elmt e2)
 Returns the product of the two elements as an element of this group.
Elmt multInverse (Elmt e)
 Returns $e^{-1}$ as an element of this group.
Elmt exponentiation (Elmt e, Elmt s)
 Returns the $e^s$ as an element of this group.
unsigned int getLeafSize ()
 Returns the byte size the leaves representing element of this group must have.
bool isIn (mpz_class r)
 Returns true if and only if $r^{order}$ is equal to 1.
std::string getType ()
 Returns a string containing the name of this Group.
- Public Member Functions inherited from arithm::Group
 Group (mpz_class order, mpz_class gen)
 Sets the attributes of a new group instance.
bool compare (Elmt e1, Elmt e2)
 Returns true if e1 and e2 have identical values, false otherwise.
ArrayOfElmts multiplication (ArrayOfElmts e1, ArrayOfElmts e2)
 Returns $R ~|~ R_i = e_{1,i} \times e_{2,i}$ as an array of elements of this group.
ArrayOfElmts multInverse (ArrayOfElmts e)
 Returns $R ~|~ R_i = e_i^{-1}$ as an array of elements of this group.
ArrayOfElmts exponentiation (ArrayOfElmts e, ArrayOfElmts s)
 Returns $R ~|~ R_i = e_i^{s_i}$ as an array of elements of this group.
Elmt product (ArrayOfElmts e)
 Returns $r = \prod e_i$ as an element of this group.
Elmt expProduct (ArrayOfElmts e, ArrayOfElmts s)
 Returns $r = \prod e_i^{s_i}$ as an element of this group.
bool compare (ArrayOfElmts e1, ArrayOfElmts e2)
 Returns true if e1 and e2 have identical values component-wise, false if at least one of the component is different.
virtual Elmt encode (std::vector< uint8_t > message)
 Encodes the message into a element of this group.
virtual std::vector< uint8_t > decode (Elmt e)
 Returns the element encoded in the element given as a paramater.
Elmt getOne ()
 Returns an element containing the unit of this group.
ArrayOfElmts getOne (unsigned int n)
 Returns an array containing n copies of the unit of this group.
Elmt getElmt (mpz_class repr)
 Returns the element of this group which has repr as a representative.
Elmt getElmt (verifierUtils::ByteTree *bt)
 Returns the element of this group which bt as a bytetree representation.
ArrayOfElmts getArray (verifierUtils::ByteTree *bt)
 Returns the array of elements of this group which has bt as a bytetree representation.
mpz_class getMultOrder ()
 Returns the multiplicative generator of this group.
Elmt getGenerator ()
 Returns the multiplicative generator of this group as an element of this group.
ArrayOfElmts getGenerator (unsigned int n)
 Returns an array containing n copies of the multiplicative order of this group.

Private Attributes

uint8_t code
 The type of encoding to use to parse and store messages using Elmts of this group.
mpz_class addOrder
 The additive order of the base ModField.

Additional Inherited Members

- Protected Attributes inherited from arithm::PSubGroup
Group * baseGroup
 The group this instance is a p-subgroup of.
mpz_class coOrder
 The order of baseGroup divided by that of this one.

Detailed Description

Implements a q-subgroup of a modular field.

Definition at line 23 of file modpgrp.hpp.

Constructor & Destructor Documentation

ModPGrp::ModPGrp ( mpz_class  ord,
mpz_class  add,
mpz_class  gen,
uint8_t  encoding 
)

Initializes a modular p-subgroup of order ord by building a new ModField instance of order add, setting it to be the baseGroup and using gen as a generator.

Definition at line 18 of file modpgrp.cpp.

:
PSubGroup(new ModField(add), ord, gen)
{
code = encoding;
addOrder = add;
}
ModPGrp::ModPGrp ( verifierUtils::ByteTree *  bt)

Parses a ByteTree to create a ModPGrp.

Parameters
btA Node containing 4 leaves:
  • the additive order
  • the order of this subgroup
  • the generator
  • the encoding to use

Definition at line 27 of file modpgrp.cpp.

:
PSubGroup(new ModField(bt->getChild(0)->toInteger()),
bt->getChild(1)->toInteger(),
bt->getChild(2)->toInteger())
{
if (!bt->isNode())
{
std::cout<<"ERROR: in ModPGrp(bt), bt is not a node. "
<<"\nbt=";
bt->prettyPrint("");
std::cout<<std::endl;
exit(1);
}
addOrder = bt->getChild(0)->toInteger();
code = bt->getChild(3)->toInteger().get_ui();
}

Member Function Documentation

ArrayOfElmts ModPGrp::getRandArray ( cryptoTools::PRG *  prg,
unsigned int  nr,
unsigned int  n0 
)
virtual

Returns an array of elements of size n0 derived using a prg.

Parameters
prgThe pseudo-random generator to use.
nrThe statistical distance to use.
n0The size of the array.

Reimplemented from arithm::Group.

Definition at line 57 of file modpgrp.cpp.

{
ArrayOfElmts result;
unsigned int np = mpz_sizeinbase(addOrder.get_mpz_t(),2);
unsigned int tiLength = (np+nr)/8; // The byte length of the
// t_i:s
mpz_class ti(0);
mpz_class base(2),
modulo(0);
mpz_pow_ui(modulo.get_mpz_t(),
base.get_mpz_t(),
np+nr);
for (unsigned int i=0; i<n0; i++)
{
ti = 0;
for (unsigned int j=0; j<=tiLength; j++)
ti = ti*0x100 + prg->getNextRandByte();
ti = (ti % modulo);
// don't use ->exponentiation as 'ti' may well
// not be in 'field'
mpz_powm(ti.get_mpz_t(),
ti.get_mpz_t(),
coOrder.get_mpz_t(),
addOrder.get_mpz_t());
result.addElmt(getElmt(ti));
}
return result;
}
verifierUtils::ByteTree * ModPGrp::toByteTree ( )
virtual

Returns the bytetree representation of this group.

Reimplemented from arithm::Group.

Definition at line 45 of file modpgrp.cpp.

{
unsigned int length = getLeafSize();
verifierUtils::ByteTree * res = new verifierUtils::Node();
res->addChild(new verifierUtils::Leaf(addOrder,length));
res->addChild(new verifierUtils::Leaf(multOrder,length));
res->addChild(new verifierUtils::Leaf(generator,length));
res->addChild(new verifierUtils::Leaf(code,4));
return res;
}

Member Data Documentation

mpz_class arithm::ModPGrp::addOrder
private

The additive order of the base ModField.

Definition at line 35 of file modpgrp.hpp.

uint8_t arithm::ModPGrp::code
private

The type of encoding to use to parse and store messages using Elmts of this group.

Definition at line 30 of file modpgrp.hpp.

The documentation for this class was generated from the following files:
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