120 lines
3.7 KiB
C
120 lines
3.7 KiB
C
/*
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* Copyright (C) 2014 FH Bielefeld
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*
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* This file is part of a FH Bielefeld project.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301 USA
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*/
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/**
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* @file ascii_poly.h
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* Header for the internal API of ascii_poly.c.
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* @brief header for ascii_poly.c
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*/
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#ifndef NTRU_ASCII_POLY_H_
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#define NTRU_ASCII_POLY_H_
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#include "common.h"
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#include "context.h"
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#include <fmpz_poly.h>
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#include <fmpz.h>
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/**
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* Convert an ascii string to an array of ternary polyomials.
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* The ascii string will be converted to a binary representation
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* and the following mapping will apply between binary -> poly:
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*
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* 1 => 1
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*
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* 0 => -1
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*
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* If the last polynomial is of degree less than N -1, then it will
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* be filled with trailing 2's for later use in tern_poly_to_ascii().
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*
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* @param to_poly the string to get into ternary polynomial format
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* @param ctx the NTRUEncrypt context
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* @return newly allocated array of ternary polynomials
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*/
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fmpz_poly_t **
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ascii_to_tern_poly(char *to_poly, ntru_context *ctx);
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/**
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* Convert an ascii string to an array of polyomials with coefficients
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* which are expected to be in the range {0, q-1}.
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* The chars will be converted to their integer representation and
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* directly put into the coefficients.
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*
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* If the last polynomial is of degree less than N -1, then it will
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* be filled with trailing q's for later user in poly_to_ascii().
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*
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* @param to_poly the string to get into polynomial format,
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* which is of type string, so we can iterate safely over it
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* (the string might have null-bytes in the middle of it)
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* @param ctx the NTRUEncrypt context
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* @return newly allocated array of polynomials
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*/
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fmpz_poly_t **
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ascii_to_poly(string *to_poly, ntru_context *ctx);
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/**
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* Convert an array of ternary polynomials back to a real string.
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* The polynomial coefficients represent a binary format of the
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* ascii string with the following mapping:
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*
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* 1 => 1
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*
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* -1 => 0
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*
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* 2 => 0
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*
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* The 2's are only used for filling up the last polynomial, so they will
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* just end up as '\0's at the end of the string and will not confuse
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* the result.
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*
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* @param tern_poly_arr the array of polynomials
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* @param ctx the NTRUEncrypt context
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* @return the real string, newly allocated
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*/
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char *
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tern_poly_to_ascii(fmpz_poly_t **tern_poly_arr, ntru_context *ctx);
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/**
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* Convert an array of polynomials back to a real string.
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* The polynomial coefficients are expected to be in the range
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* {0, q-1} and will be casted back to chars without any mapping.
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*
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* Trailing q's are only used for filling up the last polynomial,
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* so they will just end up as '\0's at the end of the string and
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* will not confuse the result.
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*
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* A struct of type string is returned, because we cannot
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* rely on null-termination in ascii_to_poly(), since there
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* may be null-bytes in the middle of the string as well.
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*
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* @param poly_arr the array of polynomials
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* @param ctx the NTRUEncrypt context
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* @return the real string, newly allocated
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*/
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string *
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poly_to_ascii(fmpz_poly_t **poly_arr, ntru_context *ctx);
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#endif /* NTRU_ASCII_POLY_H_ */
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