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

1.1     ! misho       1: /*
        !             2:  * Copyright (C) 2013 Tobias Brunner
        !             3:  * HSR Hochschule fuer Technik Rapperswil
        !             4:  *
        !             5:  * This program is free software; you can redistribute it and/or modify it
        !             6:  * under the terms of the GNU General Public License as published by the
        !             7:  * Free Software Foundation; either version 2 of the License, or (at your
        !             8:  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
        !             9:  *
        !            10:  * This program is distributed in the hope that it will be useful, but
        !            11:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            12:  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
        !            13:  * for more details.
        !            14:  */
        !            15: 
        !            16: #include "iv_gen_seq.h"
        !            17: 
        !            18: /**
        !            19:  * Magic value for the initial IV state
        !            20:  */
        !            21: #define SEQ_IV_INIT_STATE (~(uint64_t)0)
        !            22: #define SEQ_IV_HIGH_MASK (1ULL << 63)
        !            23: 
        !            24: typedef struct private_iv_gen_t private_iv_gen_t;
        !            25: 
        !            26: /**
        !            27:  * Private data of an iv_gen_t object.
        !            28:  */
        !            29: struct private_iv_gen_t {
        !            30: 
        !            31:        /**
        !            32:         * Public iv_gen_t interface.
        !            33:         */
        !            34:        iv_gen_t public;
        !            35: 
        !            36:        /**
        !            37:         * Previously passed sequence number in lower space to enforce uniqueness
        !            38:         */
        !            39:        uint64_t prevl;
        !            40: 
        !            41:        /**
        !            42:         * Previously passed sequence number in upper space to enforce uniqueness
        !            43:         */
        !            44:        uint64_t prevh;
        !            45: 
        !            46:        /**
        !            47:         * Salt to mask counter
        !            48:         */
        !            49:        uint8_t *salt;
        !            50: };
        !            51: 
        !            52: METHOD(iv_gen_t, get_iv, bool,
        !            53:        private_iv_gen_t *this, uint64_t seq, size_t size, uint8_t *buffer)
        !            54: {
        !            55:        uint8_t iv[sizeof(uint64_t)];
        !            56:        size_t len = size;
        !            57: 
        !            58:        if (!this->salt)
        !            59:        {
        !            60:                return FALSE;
        !            61:        }
        !            62:        if (size < sizeof(uint64_t))
        !            63:        {
        !            64:                return FALSE;
        !            65:        }
        !            66:        if (this->prevl != SEQ_IV_INIT_STATE && seq <= this->prevl)
        !            67:        {
        !            68:                seq |= SEQ_IV_HIGH_MASK;
        !            69:                if (this->prevh != SEQ_IV_INIT_STATE && seq <= this->prevh)
        !            70:                {
        !            71:                        return FALSE;
        !            72:                }
        !            73:        }
        !            74:        if ((seq | SEQ_IV_HIGH_MASK) == SEQ_IV_INIT_STATE)
        !            75:        {
        !            76:                return FALSE;
        !            77:        }
        !            78:        if (seq & SEQ_IV_HIGH_MASK)
        !            79:        {
        !            80:                this->prevh = seq;
        !            81:        }
        !            82:        else
        !            83:        {
        !            84:                this->prevl = seq;
        !            85:        }
        !            86:        if (len > sizeof(uint64_t))
        !            87:        {
        !            88:                len = sizeof(uint64_t);
        !            89:                memset(buffer, 0, size - len);
        !            90:        }
        !            91:        htoun64(iv, seq);
        !            92:        memxor(iv, this->salt, sizeof(uint64_t));
        !            93:        memcpy(buffer + size - len, iv + sizeof(uint64_t) - len, len);
        !            94:        return TRUE;
        !            95: }
        !            96: 
        !            97: METHOD(iv_gen_t, allocate_iv, bool,
        !            98:        private_iv_gen_t *this, uint64_t seq, size_t size, chunk_t *chunk)
        !            99: {
        !           100:        *chunk = chunk_alloc(size);
        !           101:        if (!get_iv(this, seq, chunk->len, chunk->ptr))
        !           102:        {
        !           103:                chunk_free(chunk);
        !           104:                return FALSE;
        !           105:        }
        !           106:        return TRUE;
        !           107: }
        !           108: 
        !           109: METHOD(iv_gen_t, destroy, void,
        !           110:        private_iv_gen_t *this)
        !           111: {
        !           112:        free(this->salt);
        !           113:        free(this);
        !           114: }
        !           115: 
        !           116: iv_gen_t *iv_gen_seq_create()
        !           117: {
        !           118:        private_iv_gen_t *this;
        !           119:        rng_t *rng;
        !           120: 
        !           121:        INIT(this,
        !           122:                .public = {
        !           123:                        .get_iv = _get_iv,
        !           124:                        .allocate_iv = _allocate_iv,
        !           125:                        .destroy = _destroy,
        !           126:                },
        !           127:                .prevl = SEQ_IV_INIT_STATE,
        !           128:                .prevh = SEQ_IV_INIT_STATE,
        !           129:        );
        !           130: 
        !           131:        rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);
        !           132:        if (rng)
        !           133:        {
        !           134:                this->salt = malloc(sizeof(uint64_t));
        !           135:                if (!rng->get_bytes(rng, sizeof(uint64_t), this->salt))
        !           136:                {
        !           137:                        free(this->salt);
        !           138:                        this->salt = NULL;
        !           139:                }
        !           140:                rng->destroy(rng);
        !           141:        }
        !           142: 
        !           143:        return &this->public;
        !           144: }