69 lines
2.3 KiB
Go
69 lines
2.3 KiB
Go
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// Copyright 2017-2018 DERO Project. All rights reserved.
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// Use of this source code in any form is governed by RESEARCH license.
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// license can be found in the LICENSE file.
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// GPG: 0F39 E425 8C65 3947 702A 8234 08B2 0360 A03A 9DE8
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//
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
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// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package dvm
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import "encoding/binary"
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import "golang.org/x/crypto/salsa20/salsa"
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import "github.com/deroproject/derohe/cryptography/crypto"
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/* this file implements a deterministic random number generator
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the random number space is quite large but still unattackable, since the seeds are random
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the seeds depend on the BLID and the TXID, if an attacker can somehow control the TXID,
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he will not be able to control BLID
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*/
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type RND struct {
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Key [32]byte
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Pos uint64 // we will wrap around in 2^64 times but this is per TX,BLOCK,SCID
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}
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// make sure 2 SCs cannot ever generate same series of random numbers
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func Initialize_RND(SCID, BLID, TXID crypto.Hash) (r *RND) {
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r = &RND{}
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tmp := crypto.Keccak256(SCID[:], BLID[:], TXID[:])
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copy(r.Key[:], tmp[:])
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r.Pos = 1 // we start at 1 to eliminate an edge case
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return // TODO we must reinitialize using blid and other parameters
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}
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func (r *RND) Random() uint64 {
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var out [32]byte
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var in [16]byte
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var key [32]byte
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copy(key[:], r.Key[:])
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binary.BigEndian.PutUint64(in[:], r.Pos)
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salsa.HSalsa20(&out, &in, &key, &in)
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deterministic_value := binary.BigEndian.Uint64(out[:])
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r.Pos++
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return deterministic_value
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}
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// range to (input-1)
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func (r *RND) Random_MAX(input uint64) uint64 {
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if input == 0 {
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panic("RNG cannot generate RND with 0 as max")
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}
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return r.Random() % input
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}
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