github.com/jiajun1992/watercarver@v0.0.0-20191031150618-dfc2b17c0c4a/go-ethereum/ctcrypto/crypto/ringct/key.go (about)

     1  // Copyright 2017-2018 DERO Project. All rights reserved.
     2  // Use of this source code in any form is governed by RESEARCH license.
     3  // license can be found in the LICENSE file.
     4  // GPG: 0F39 E425 8C65 3947 702A  8234 08B2 0360 A03A 9DE8
     5  //
     6  //
     7  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
     8  // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     9  // MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
    10  // THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    11  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
    12  // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
    13  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    14  // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
    15  // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    16  
    17  package ringct
    18  
    19  //import "io"
    20  //import "fmt"
    21  //import "crypto/rand"
    22  
    23  import "github.com/ethereum/go-ethereum/ctcrypto/crypto"
    24  
    25  // bothe the function resturn identity of the ed25519 curve
    26  func identity() (result *crypto.Key) {
    27  	result = new(crypto.Key)
    28  	result[0] = 1
    29  	return
    30  }
    31  
    32  func D2h(val uint64) (result *crypto.Key) {
    33  	return d2h(val)
    34  }
    35  
    36  // convert a uint64 to a scalar
    37  func d2h(val uint64) (result *crypto.Key) {
    38  	result = new(crypto.Key)
    39  	for i := 0; val > 0; i++ {
    40  		result[i] = byte(val & 0xFF)
    41  		val /= 256
    42  	}
    43  	return
    44  }
    45  
    46  func H2d(input crypto.Key) (value uint64) {
    47  	return h2d(input)
    48  }
    49  
    50  //32 byte key to uint long long
    51  // if the key holds a value > 2^64
    52  // then the value in the first 8 bytes is returned
    53  func h2d(input crypto.Key) (value uint64) {
    54  	for j := 7; j >= 0; j-- {
    55  		value = (value*256 + uint64(input[j]))
    56  	}
    57  	return value
    58  }
    59  
    60  // this gives you a commitment from an amount
    61  // this is used to convert tx fee or miner tx amount to commitment
    62  func Commitment_From_Amount(amount uint64) crypto.Key {
    63  	return *(crypto.ScalarMultH(d2h(amount)))
    64  }
    65  
    66  // this is used to convert miner tx commitment to  mask
    67  // equivalent to rctOps.cpp zeroCommit
    68  func ZeroCommitment_From_Amount(amount uint64) crypto.Key {
    69  	mask := *(identity())
    70  	mask = crypto.ScalarmultBase(mask)
    71  	am := d2h(amount)
    72  	bH := crypto.ScalarMultH(am)
    73  	crypto.AddKeys(&mask, &mask, bH)
    74  	return mask
    75  }