507 lines
12 KiB
C
507 lines
12 KiB
C
/*
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* Copyright (C) 2017-2018 Tobias Brunner
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* Copyright (C) 2005-2009 Martin Willi
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* Copyright (C) 2005 Jan Hutter
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* HSR Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <gmp.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include "gmp_rsa_public_key.h"
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#include <utils/debug.h>
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#include <asn1/oid.h>
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#include <asn1/asn1.h>
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#include <asn1/asn1_parser.h>
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#include <crypto/hashers/hasher.h>
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#include <credentials/keys/signature_params.h>
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#ifdef HAVE_MPZ_POWM_SEC
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# undef mpz_powm
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# define mpz_powm mpz_powm_sec
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#endif
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typedef struct private_gmp_rsa_public_key_t private_gmp_rsa_public_key_t;
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/**
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* Private data structure with signing context.
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*/
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struct private_gmp_rsa_public_key_t {
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/**
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* Public interface for this signer.
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*/
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gmp_rsa_public_key_t public;
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/**
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* Public modulus.
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*/
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mpz_t n;
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/**
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* Public exponent.
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*/
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mpz_t e;
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/**
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* Keysize in bytes.
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*/
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size_t k;
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/**
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* reference counter
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*/
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refcount_t ref;
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};
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/**
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* Shared functions defined in gmp_rsa_private_key.c
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*/
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chunk_t gmp_mpz_to_chunk(const mpz_t value);
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bool gmp_emsa_pkcs1_signature_data(hash_algorithm_t hash_algorithm,
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chunk_t data, size_t keylen, chunk_t *em);
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/**
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* RSAEP algorithm specified in PKCS#1.
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*/
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static chunk_t rsaep(private_gmp_rsa_public_key_t *this, chunk_t data)
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{
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mpz_t m, c;
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chunk_t encrypted;
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mpz_init(m);
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mpz_import(m, data.len, 1, 1, 1, 0, data.ptr);
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if (mpz_cmp_ui(m, 0) <= 0 || mpz_cmp(m, this->n) >= 0)
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{ /* m must be <= n-1, and while 0 is technically a valid value, it
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* doesn't really make sense here, so we filter that too */
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mpz_clear(m);
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return chunk_empty;
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}
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mpz_init(c);
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mpz_powm(c, m, this->e, this->n);
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encrypted.len = this->k;
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encrypted.ptr = mpz_export(NULL, NULL, 1, encrypted.len, 1, 0, c);
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if (encrypted.ptr == NULL)
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{
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encrypted.len = 0;
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}
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mpz_clear(c);
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mpz_clear(m);
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return encrypted;
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}
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/**
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* RSAVP1 algorithm specified in PKCS#1.
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*/
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static chunk_t rsavp1(private_gmp_rsa_public_key_t *this, chunk_t data)
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{
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return rsaep(this, data);
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}
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/**
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* Verification of an EMSA PKCS1 signature described in PKCS#1
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*/
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static bool verify_emsa_pkcs1_signature(private_gmp_rsa_public_key_t *this,
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hash_algorithm_t algorithm,
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chunk_t data, chunk_t signature)
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{
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chunk_t em_expected, em;
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bool success = FALSE;
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/* remove any preceding 0-bytes from signature */
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while (signature.len && *(signature.ptr) == 0x00)
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{
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signature = chunk_skip(signature, 1);
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}
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if (signature.len == 0 || signature.len > this->k)
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{
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return FALSE;
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}
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/* generate expected signature value */
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if (!gmp_emsa_pkcs1_signature_data(algorithm, data, this->k, &em_expected))
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{
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return FALSE;
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}
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/* unpack signature */
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em = rsavp1(this, signature);
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success = chunk_equals_const(em_expected, em);
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chunk_free(&em_expected);
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chunk_free(&em);
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return success;
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}
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/**
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* Verification of an EMSA PSS signature described in PKCS#1
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*/
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static bool verify_emsa_pss_signature(private_gmp_rsa_public_key_t *this,
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rsa_pss_params_t *params, chunk_t data,
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chunk_t signature)
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{
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ext_out_function_t xof;
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hasher_t *hasher = NULL;
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xof_t *mgf = NULL;
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chunk_t em, hash, salt, db, h, dbmask, m;
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size_t embits, maskbits;
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int i;
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bool success = FALSE;
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if (!params)
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{
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return FALSE;
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}
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xof = xof_mgf1_from_hash_algorithm(params->mgf1_hash);
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if (xof == XOF_UNDEFINED)
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{
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DBG1(DBG_LIB, "%N is not supported for MGF1", hash_algorithm_names,
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params->mgf1_hash);
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return FALSE;
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}
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chunk_skip_zero(signature);
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if (signature.len == 0 || signature.len > this->k)
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{
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return FALSE;
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}
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/* EM = RSAVP1((n, e), S) */
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em = rsavp1(this, signature);
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if (!em.len)
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{
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goto error;
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}
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/* emBits = modBits - 1 */
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embits = mpz_sizeinbase(this->n, 2) - 1;
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/* mHash = Hash(M) */
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hasher = lib->crypto->create_hasher(lib->crypto, params->hash);
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if (!hasher)
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{
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DBG1(DBG_LIB, "hash algorithm %N not supported",
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hash_algorithm_names, params->hash);
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goto error;
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}
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hash = chunk_alloca(hasher->get_hash_size(hasher));
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if (!hasher->get_hash(hasher, data, hash.ptr))
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{
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goto error;
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}
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salt.len = params->salt_len;
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/* verify general structure of EM */
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maskbits = (8 * em.len) - embits;
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if (em.len < (hash.len + salt.len + 2) || em.ptr[em.len-1] != 0xbc ||
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(em.ptr[0] & (0xff << (8-maskbits))))
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{ /* inconsistent */
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goto error;
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}
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/* split EM in maskedDB and H */
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db = chunk_create(em.ptr, em.len - hash.len - 1);
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h = chunk_create(em.ptr + db.len, hash.len);
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/* dbMask = MGF(H, emLen - hLen - 1) */
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mgf = lib->crypto->create_xof(lib->crypto, xof);
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if (!mgf)
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{
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DBG1(DBG_LIB, "%N not supported", ext_out_function_names, xof);
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goto error;
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}
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dbmask = chunk_alloca(db.len);
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if (!mgf->set_seed(mgf, h) ||
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!mgf->get_bytes(mgf, dbmask.len, dbmask.ptr))
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{
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DBG1(DBG_LIB, "%N not supported or failed", ext_out_function_names, xof);
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goto error;
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}
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/* DB = maskedDB xor dbMask */
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memxor(db.ptr, dbmask.ptr, db.len);
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if (maskbits)
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{
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db.ptr[0] &= (0xff >> maskbits);
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}
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/* check DB = PS | 0x01 | salt */
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for (i = 0; i < (db.len - salt.len - 1); i++)
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{
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if (db.ptr[i])
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{ /* padding not 0 */
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goto error;
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}
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}
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if (db.ptr[i++] != 0x01)
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{ /* 0x01 not found */
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goto error;
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}
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salt.ptr = &db.ptr[i];
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/* M' = 0x0000000000000000 | mHash | salt */
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m = chunk_cata("ccc",
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chunk_from_chars(0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00),
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hash, salt);
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if (!hasher->get_hash(hasher, m, hash.ptr))
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{
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goto error;
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}
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success = memeq_const(h.ptr, hash.ptr, hash.len);
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error:
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DESTROY_IF(hasher);
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DESTROY_IF(mgf);
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free(em.ptr);
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return success;
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}
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METHOD(public_key_t, get_type, key_type_t,
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private_gmp_rsa_public_key_t *this)
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{
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return KEY_RSA;
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}
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METHOD(public_key_t, verify, bool,
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private_gmp_rsa_public_key_t *this, signature_scheme_t scheme, void *params,
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chunk_t data, chunk_t signature)
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{
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switch (scheme)
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{
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case SIGN_RSA_EMSA_PKCS1_NULL:
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return verify_emsa_pkcs1_signature(this, HASH_UNKNOWN, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA2_224:
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return verify_emsa_pkcs1_signature(this, HASH_SHA224, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA2_256:
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return verify_emsa_pkcs1_signature(this, HASH_SHA256, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA2_384:
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return verify_emsa_pkcs1_signature(this, HASH_SHA384, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA2_512:
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return verify_emsa_pkcs1_signature(this, HASH_SHA512, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA3_224:
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return verify_emsa_pkcs1_signature(this, HASH_SHA3_224, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA3_256:
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return verify_emsa_pkcs1_signature(this, HASH_SHA3_256, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA3_384:
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return verify_emsa_pkcs1_signature(this, HASH_SHA3_384, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA3_512:
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return verify_emsa_pkcs1_signature(this, HASH_SHA3_512, data, signature);
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case SIGN_RSA_EMSA_PKCS1_SHA1:
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return verify_emsa_pkcs1_signature(this, HASH_SHA1, data, signature);
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case SIGN_RSA_EMSA_PKCS1_MD5:
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return verify_emsa_pkcs1_signature(this, HASH_MD5, data, signature);
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case SIGN_RSA_EMSA_PSS:
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return verify_emsa_pss_signature(this, params, data, signature);
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default:
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DBG1(DBG_LIB, "signature scheme %N not supported in RSA",
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signature_scheme_names, scheme);
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return FALSE;
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}
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}
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#define MIN_PS_PADDING 8
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METHOD(public_key_t, encrypt_, bool,
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private_gmp_rsa_public_key_t *this, encryption_scheme_t scheme,
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chunk_t plain, chunk_t *crypto)
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{
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chunk_t em;
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u_char *pos;
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int padding;
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rng_t *rng;
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if (scheme != ENCRYPT_RSA_PKCS1)
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{
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DBG1(DBG_LIB, "encryption scheme %N not supported",
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encryption_scheme_names, scheme);
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return FALSE;
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}
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/* number of pseudo-random padding octets */
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padding = this->k - plain.len - 3;
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if (padding < MIN_PS_PADDING)
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{
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DBG1(DBG_LIB, "pseudo-random padding must be at least %d octets",
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MIN_PS_PADDING);
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return FALSE;
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}
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rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
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if (rng == NULL)
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{
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DBG1(DBG_LIB, "no random generator available");
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return FALSE;
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}
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/* padding according to PKCS#1 7.2.1 (RSAES-PKCS1-v1.5-ENCRYPT) */
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DBG2(DBG_LIB, "padding %u bytes of data to the rsa modulus size of"
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" %u bytes", plain.len, this->k);
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em.len = this->k;
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em.ptr = malloc(em.len);
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pos = em.ptr;
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*pos++ = 0x00;
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*pos++ = 0x02;
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/* fill with pseudo random octets */
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if (!rng_get_bytes_not_zero(rng, padding, pos, TRUE))
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{
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DBG1(DBG_LIB, "failed to allocate padding");
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chunk_clear(&em);
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rng->destroy(rng);
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return FALSE;
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}
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rng->destroy(rng);
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pos += padding;
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/* append the padding terminator */
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*pos++ = 0x00;
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/* now add the data */
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memcpy(pos, plain.ptr, plain.len);
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DBG3(DBG_LIB, "padded data before rsa encryption: %B", &em);
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/* rsa encryption using PKCS#1 RSAEP */
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*crypto = rsaep(this, em);
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DBG3(DBG_LIB, "rsa encrypted data: %B", crypto);
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chunk_clear(&em);
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return TRUE;
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}
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METHOD(public_key_t, get_keysize, int,
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private_gmp_rsa_public_key_t *this)
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{
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return mpz_sizeinbase(this->n, 2);
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}
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METHOD(public_key_t, get_encoding, bool,
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private_gmp_rsa_public_key_t *this, cred_encoding_type_t type,
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chunk_t *encoding)
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{
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chunk_t n, e;
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bool success;
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n = gmp_mpz_to_chunk(this->n);
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e = gmp_mpz_to_chunk(this->e);
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success = lib->encoding->encode(lib->encoding, type, NULL, encoding,
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CRED_PART_RSA_MODULUS, n, CRED_PART_RSA_PUB_EXP, e, CRED_PART_END);
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chunk_free(&n);
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chunk_free(&e);
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return success;
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}
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METHOD(public_key_t, get_fingerprint, bool,
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private_gmp_rsa_public_key_t *this, cred_encoding_type_t type, chunk_t *fp)
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{
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chunk_t n, e;
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bool success;
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if (lib->encoding->get_cache(lib->encoding, type, this, fp))
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{
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return TRUE;
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}
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n = gmp_mpz_to_chunk(this->n);
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e = gmp_mpz_to_chunk(this->e);
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success = lib->encoding->encode(lib->encoding, type, this, fp,
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CRED_PART_RSA_MODULUS, n, CRED_PART_RSA_PUB_EXP, e, CRED_PART_END);
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chunk_free(&n);
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chunk_free(&e);
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return success;
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}
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METHOD(public_key_t, get_ref, public_key_t*,
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private_gmp_rsa_public_key_t *this)
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{
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ref_get(&this->ref);
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return &this->public.key;
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}
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METHOD(public_key_t, destroy, void,
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private_gmp_rsa_public_key_t *this)
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{
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if (ref_put(&this->ref))
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{
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mpz_clear(this->n);
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mpz_clear(this->e);
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lib->encoding->clear_cache(lib->encoding, this);
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free(this);
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}
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}
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/**
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* See header.
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*/
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gmp_rsa_public_key_t *gmp_rsa_public_key_load(key_type_t type, va_list args)
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{
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private_gmp_rsa_public_key_t *this;
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chunk_t n, e;
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n = e = chunk_empty;
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while (TRUE)
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{
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switch (va_arg(args, builder_part_t))
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{
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case BUILD_RSA_MODULUS:
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n = va_arg(args, chunk_t);
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continue;
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case BUILD_RSA_PUB_EXP:
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e = va_arg(args, chunk_t);
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continue;
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case BUILD_END:
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break;
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default:
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return NULL;
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}
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break;
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}
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if (!e.len || !n.len || (n.ptr[n.len-1] & 0x01) == 0)
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{
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return NULL;
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}
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INIT(this,
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.public = {
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.key = {
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.get_type = _get_type,
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.verify = _verify,
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.encrypt = _encrypt_,
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.equals = public_key_equals,
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.get_keysize = _get_keysize,
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.get_fingerprint = _get_fingerprint,
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.has_fingerprint = public_key_has_fingerprint,
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.get_encoding = _get_encoding,
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.get_ref = _get_ref,
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.destroy = _destroy,
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},
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},
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.ref = 1,
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);
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mpz_init(this->n);
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mpz_init(this->e);
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mpz_import(this->n, n.len, 1, 1, 1, 0, n.ptr);
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mpz_import(this->e, e.len, 1, 1, 1, 0, e.ptr);
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this->k = (mpz_sizeinbase(this->n, 2) + 7) / BITS_PER_BYTE;
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if (!mpz_sgn(this->e))
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{
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destroy(this);
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return NULL;
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}
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return &this->public;
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}
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