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Annotation of embedaddon/strongswan/src/libstrongswan/crypto/prf_plus.c, revision 1.1

1.1     ! misho       1: /*
        !             2:  * Copyright (C) 2005-2006 Martin Willi
        !             3:  * Copyright (C) 2005 Jan Hutter
        !             4:  * HSR Hochschule fuer Technik Rapperswil
        !             5:  *
        !             6:  * This program is free software; you can redistribute it and/or modify it
        !             7:  * under the terms of the GNU General Public License as published by the
        !             8:  * Free Software Foundation; either version 2 of the License, or (at your
        !             9:  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
        !            10:  *
        !            11:  * This program is distributed in the hope that it will be useful, but
        !            12:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            13:  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
        !            14:  * for more details.
        !            15:  */
        !            16: 
        !            17: #include <string.h>
        !            18: 
        !            19: #include "prf_plus.h"
        !            20: 
        !            21: typedef struct private_prf_plus_t private_prf_plus_t;
        !            22: 
        !            23: typedef bool (*apply_prf_t)(private_prf_plus_t *this);
        !            24: 
        !            25: /**
        !            26:  * Private data of an prf_plus_t object.
        !            27:  *
        !            28:  */
        !            29: struct private_prf_plus_t {
        !            30: 
        !            31:        /**
        !            32:         * Public interface of prf_plus_t.
        !            33:         */
        !            34:        prf_plus_t public;
        !            35: 
        !            36:        /**
        !            37:         * PRF to use.
        !            38:         */
        !            39:        prf_t *prf;
        !            40: 
        !            41:        /**
        !            42:         * Initial seed.
        !            43:         */
        !            44:        chunk_t seed;
        !            45: 
        !            46:        /**
        !            47:         * Octet which will be appended to the seed if a counter is used.
        !            48:         */
        !            49:        uint8_t counter;
        !            50: 
        !            51:        /**
        !            52:         * Already given out bytes in current buffer.
        !            53:         */
        !            54:        size_t used;
        !            55: 
        !            56:        /**
        !            57:         * Buffer to store current PRF result.
        !            58:         */
        !            59:        chunk_t buffer;
        !            60: 
        !            61:        /**
        !            62:         * The prf application method depending on whether a counter is used.
        !            63:         */
        !            64:        apply_prf_t apply_prf;
        !            65: };
        !            66: 
        !            67: /**
        !            68:  * Apply the PRF using the running counter
        !            69:  */
        !            70: static bool apply_prf_counter(private_prf_plus_t *this)
        !            71: {
        !            72:        if (!this->prf->get_bytes(this->prf, this->seed, NULL) ||
        !            73:                !this->prf->get_bytes(this->prf, chunk_from_thing(this->counter),
        !            74:                                                          this->buffer.ptr))
        !            75:        {
        !            76:                return FALSE;
        !            77:        }
        !            78:        this->counter++;
        !            79:        if (!this->counter)
        !            80:        {       /* according to RFC 7296, section 2.13, prf+ is undefined once the
        !            81:                 * counter wrapped, so let's fail for future calls */
        !            82:                this->apply_prf = (void*)return_false;
        !            83:        }
        !            84:        return TRUE;
        !            85: }
        !            86: 
        !            87: /**
        !            88:  * Apply the PRF using the running counter
        !            89:  */
        !            90: static bool apply_prf(private_prf_plus_t *this)
        !            91: {
        !            92:        return this->prf->get_bytes(this->prf, this->seed, this->buffer.ptr);
        !            93: }
        !            94: 
        !            95: METHOD(prf_plus_t, get_bytes, bool,
        !            96:        private_prf_plus_t *this, size_t length, uint8_t *buffer)
        !            97: {
        !            98:        size_t round, written = 0;
        !            99: 
        !           100:        while (length > 0)
        !           101:        {
        !           102:                if (this->buffer.len == this->used)
        !           103:                {       /* buffer used, get next round */
        !           104:                        if (!this->prf->get_bytes(this->prf, this->buffer, NULL))
        !           105:                        {
        !           106:                                return FALSE;
        !           107:                        }
        !           108:                        if (!this->apply_prf(this))
        !           109:                        {
        !           110:                                return FALSE;
        !           111:                        }
        !           112:                        this->used = 0;
        !           113:                }
        !           114:                round = min(length, this->buffer.len - this->used);
        !           115:                memcpy(buffer + written, this->buffer.ptr + this->used, round);
        !           116: 
        !           117:                length -= round;
        !           118:                this->used += round;
        !           119:                written += round;
        !           120:        }
        !           121:        return TRUE;
        !           122: }
        !           123: 
        !           124: METHOD(prf_plus_t, allocate_bytes, bool,
        !           125:        private_prf_plus_t *this, size_t length, chunk_t *chunk)
        !           126: {
        !           127:        *chunk = chunk_alloc(length);
        !           128:        if (!get_bytes(this, length, chunk->ptr))
        !           129:        {
        !           130:                chunk_free(chunk);
        !           131:                return FALSE;
        !           132:        }
        !           133:        return TRUE;
        !           134: }
        !           135: 
        !           136: METHOD(prf_plus_t, destroy, void,
        !           137:        private_prf_plus_t *this)
        !           138: {
        !           139:        chunk_clear(&this->buffer);
        !           140:        chunk_clear(&this->seed);
        !           141:        free(this);
        !           142: }
        !           143: 
        !           144: /*
        !           145:  * Description in header.
        !           146:  */
        !           147: prf_plus_t *prf_plus_create(prf_t *prf, bool counter, chunk_t seed)
        !           148: {
        !           149:        private_prf_plus_t *this;
        !           150: 
        !           151:        INIT(this,
        !           152:                .public = {
        !           153:                        .get_bytes = _get_bytes,
        !           154:                        .allocate_bytes = _allocate_bytes,
        !           155:                        .destroy = _destroy,
        !           156:                },
        !           157:                .prf = prf,
        !           158:                .seed = chunk_clone(seed),
        !           159:                .buffer = chunk_alloc(prf->get_block_size(prf)),
        !           160:                .apply_prf = counter ? apply_prf_counter : apply_prf,
        !           161:                .counter = 0x01,
        !           162:        );
        !           163: 
        !           164:        if (!this->apply_prf(this))
        !           165:        {
        !           166:                destroy(this);
        !           167:                return NULL;
        !           168:        }
        !           169:        return &this->public;
        !           170: }