Golang big.Int类代码示例

// Creates a new STS session, ready to initiate or accept key exchanges. The group/generator pair defines the
// cyclic group on which STS will operate. cipher and bits are used during the authentication token's symmetric
// encryption, whilst hash is needed during RSA signing.
func New(random io.Reader, group, generator *big.Int, cipher func([]byte) (cipher.Block, error),
	bits int, hash crypto.Hash) (*Session, error) {
	// Generate a random secret exponent
	expbits := group.BitLen()
	secret := make([]byte, (expbits+7)/8)
	n, err := io.ReadFull(random, secret)
	if n != len(secret) || err != nil {
		return nil, err
	}

	// Clear top bits if non-power was requested
	clear := uint(expbits % 8)
	if clear == 0 {
		clear = 8
	}
	secret[0] &= uint8(int(1<<clear) - 1)

	exp := new(big.Int).SetBytes(secret)
	ses := new(Session)
	ses.group = group
	ses.generator = generator
	ses.exponent = exp
	ses.hash = hash
	ses.crypter = cipher
	ses.keybits = bits

	return ses, nil
}

// bigIntToNetIPv6 is a helper function that correctly returns a net.IP with the
// correctly padded values.
func bigIntToNetIPv6(bi *big.Int) *net.IP {
	x := make(net.IP, IPv6len)
	ipv6Bytes := bi.Bytes()

	// It's possibe for ipv6Bytes to be less than IPv6len bytes in size.  If
	// they are different sizes we to pad the size of response.
	if len(ipv6Bytes) < IPv6len {
		buf := new(bytes.Buffer)
		buf.Grow(IPv6len)

		for i := len(ipv6Bytes); i < IPv6len; i++ {
			if err := binary.Write(buf, binary.BigEndian, byte(0)); err != nil {
				panic(fmt.Sprintf("Unable to pad byte %d of input %v: %v", i, bi, err))
			}
		}

		for _, b := range ipv6Bytes {
			if err := binary.Write(buf, binary.BigEndian, b); err != nil {
				panic(fmt.Sprintf("Unable to preserve endianness of input %v: %v", bi, err))
			}
		}

		ipv6Bytes = buf.Bytes()
	}
	i := copy(x, ipv6Bytes)
	if i != IPv6len {
		panic("IPv6 wrong size")
	}
	return &x
}

// BigIntToEncodedBytes converts a big integer into its corresponding
// 32 byte little endian representation.
func BigIntToEncodedBytes(a *big.Int) *[32]byte {
	s := new([32]byte)
	if a == nil {
		return s
	}
	// Caveat: a can be longer than 32 bytes.
	aB := a.Bytes()

	// If we have a short byte string, expand
	// it so that it's long enough.
	aBLen := len(aB)
	if aBLen < fieldIntSize {
		diff := fieldIntSize - aBLen
		for i := 0; i < diff; i++ {
			aB = append([]byte{0x00}, aB...)
		}
	}

	for i := 0; i < fieldIntSize; i++ {
		s[i] = aB[i]
	}

	// Reverse the byte string --> little endian after
	// encoding.
	reverse(s)

	return s
}

// parseECPrivateKey parses an ASN.1 Elliptic Curve Private Key Structure.
// The OID for the named curve may be provided from another source (such as
// the PKCS8 container) - if it is provided then use this instead of the OID
// that may exist in the EC private key structure.
func parseECPrivateKey(namedCurveOID *asn1.ObjectIdentifier, der []byte) (key *ecdsa.PrivateKey, err error) {
	var privKey ecPrivateKey
	if _, err := asn1.Unmarshal(der, &privKey); err != nil {
		return nil, errors.New("x509: failed to parse EC private key: " + err.Error())
	}
	if privKey.Version != ecPrivKeyVersion {
		return nil, fmt.Errorf("x509: unknown EC private key version %d", privKey.Version)
	}

	var curve elliptic.Curve
	if namedCurveOID != nil {
		curve = namedCurveFromOID(*namedCurveOID)
	} else {
		curve = namedCurveFromOID(privKey.NamedCurveOID)
	}
	if curve == nil {
		return nil, errors.New("x509: unknown elliptic curve")
	}

	k := new(big.Int).SetBytes(privKey.PrivateKey)
	if k.Cmp(curve.Params().N) >= 0 {
		return nil, errors.New("x509: invalid elliptic curve private key value")
	}
	priv := new(ecdsa.PrivateKey)
	priv.Curve = curve
	priv.D = k
	priv.X, priv.Y = curve.ScalarBaseMult(privKey.PrivateKey)

	return priv, nil
}

func factor2(n *big.Int) int {
	// could be improved for large factors
	f := 0
	for ; n.Bit(f) == 0; f++ {
	}
	return f
}

func factorial(x *big.Int) *big.Int {
	n := big.NewInt(1)
	if x.Cmp(big.NewInt(0)) == 0 {
		return n
	}
	return n.Mul(x, factorial(n.Sub(x, n)))
}

// returns a formatted MIP mapped key by adding prefix, canonical number and level
//
// ex. fn(98, 1000) = (prefix || 1000 || 0)
func mipmapKey(num, level uint64) []byte {
	lkey := make([]byte, 8)
	binary.BigEndian.PutUint64(lkey, level)
	key := new(big.Int).SetUint64(num / level * level)

	return append(mipmapPre, append(lkey, key.Bytes()...)...)
}

// Big max
//
// Returns the maximum size big integer
func BigMax(x, y *big.Int) *big.Int {
	if x.Cmp(y) < 0 {
		return y
	}

	return x
}

func getWorkPackage(difficulty *big.Int) string {

	if currWork == nil {
		return getErrorResponse("Current work unavailable")
	}

	// Our response object
	response := &ResponseArray{
		Id:      currWork.Id,
		Jsonrpc: currWork.Jsonrpc,
		Result:  currWork.Result[:],
	}

	// Calculte requested difficulty
	diff := new(big.Int).Div(pow256, difficulty)
	diffBytes := string(common.ToHex(diff.Bytes()))

	// Adjust the difficulty for the miner
	response.Result[2] = diffBytes

	// Convert respone object to JSON
	b, _ := json.Marshal(response)

	return string(b)

}

func main() {
	out, _ := os.Create("485.out")
	defer out.Close()

	for !done {
		var one big.Int
		one.SetInt64(1)
		p = append(p, one)
		l := len(p)

		fmt.Fprint(out, &p[l-1])
		for i := l - 2; i > 0; i-- {
			p[i].Add(&p[i], &p[i-1])
			fmt.Fprintf(out, " %v", &p[i])

			s = fmt.Sprint(&p[i])
			if len(s) > MAX {
				done = true
				break
			}
		}

		if !done && l > 1 {
			fmt.Fprintf(out, " %v", &p[0])
		}
		fmt.Fprintln(out)
	}
}

// baseCheck checks for any stack error underflows
func baseCheck(op OpCode, stack *stack, gas *big.Int) error {
	// PUSH and DUP are a bit special. They all cost the same but we do want to have checking on stack push limit
	// PUSH is also allowed to calculate the same price for all PUSHes
	// DUP requirements are handled elsewhere (except for the stack limit check)
	if op >= PUSH1 && op <= PUSH32 {
		op = PUSH1
	}
	if op >= DUP1 && op <= DUP16 {
		op = DUP1
	}

	if r, ok := _baseCheck[op]; ok {
		err := stack.require(r.stackPop)
		if err != nil {
			return err
		}

		if r.stackPush > 0 && stack.len()-r.stackPop+r.stackPush > int(params.StackLimit.Int64()) {
			return fmt.Errorf("stack limit reached %d (%d)", stack.len(), params.StackLimit.Int64())
		}

		gas.Add(gas, r.gas)
	}
	return nil
}

func bigAdd(IntSlice []big.Int) *big.Int {
	var sum *big.Int = big.NewInt(0)
	for i := 0; i < len(IntSlice); i++ {
		sum.Add(sum, &IntSlice[i])
	}
	return sum
}

func (v *Value) String() string {
	if v.IsZero() {
		return "0"
	}
	if v.Native && v.IsScientific() {
		value := strconv.FormatUint(v.Num, 10)
		offset := strconv.FormatInt(v.Offset, 10)
		if v.Negative {
			return "-" + value + "e" + offset
		}
		return value + "e" + offset
	}
	value := big.NewInt(int64(v.Num))
	if v.Negative {
		value.Neg(value)
	}
	var offset *big.Int
	if v.Native {
		offset = big.NewInt(-6)
	} else {
		offset = big.NewInt(v.Offset)
	}
	exp := offset.Exp(bigTen, offset.Neg(offset), nil)
	rat := big.NewRat(0, 1).SetFrac(value, exp)
	left := rat.FloatString(0)
	if rat.IsInt() {
		return left
	}
	length := len(left)
	if v.Negative {
		length -= 1
	}
	return strings.TrimRight(rat.FloatString(32-length), "0")
}

func (c *StateObject) GetInstr(pc *big.Int) *common.Value {
	if int64(len(c.code)-1) < pc.Int64() {
		return common.NewValue(0)
	}

	return common.NewValueFromBytes([]byte{c.code[pc.Int64()]})
}

func (p *PrivateKeys) addRemoteKey(remote []byte, clientPacket []byte, serverPacket []byte) SharedKeys {
	remote_be := new(big.Int)
	remote_be.SetBytes(remote)
	shared_key := powm(remote_be, p.privateKey, p.prime)

	data := make([]byte, 0, 100)
	mac := hmac.New(sha1.New, shared_key.Bytes())

	for i := 1; i < 6; i++ {
		mac.Write(clientPacket)
		mac.Write(serverPacket)
		mac.Write([]byte{uint8(i)})
		data = append(data, mac.Sum(nil)...)
		mac.Reset()
	}

	mac = hmac.New(sha1.New, data[0:0x14])
	mac.Write(clientPacket)
	mac.Write(serverPacket)

	return SharedKeys{
		challenge: mac.Sum(nil),
		sendKey:   data[0x14:0x34],
		recvKey:   data[0x34:0x54],
	}
}