203 lines
5.9 KiB
Go
203 lines
5.9 KiB
Go
package secp256k1
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import (
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"bytes"
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"crypto/sha256"
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"crypto/subtle"
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"fmt"
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"io"
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"math/big"
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secp256k1 "github.com/btcsuite/btcd/btcec"
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"github.com/tendermint/tendermint/crypto"
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"golang.org/x/crypto/ripemd160" // nolint: staticcheck // necessary for Bitcoin address format
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"github.com/cosmos/cosmos-sdk/codec"
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cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
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"github.com/cosmos/cosmos-sdk/types/errors"
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)
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var _ cryptotypes.PrivKey = &PrivKey{}
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var _ codec.AminoMarshaler = &PrivKey{}
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const (
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PrivKeySize = 32
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keyType = "secp256k1"
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PrivKeyName = "tendermint/PrivKeySecp256k1"
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PubKeyName = "tendermint/PubKeySecp256k1"
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)
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// Bytes returns the byte representation of the Private Key.
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func (privKey *PrivKey) Bytes() []byte {
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return privKey.Key
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}
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// PubKey performs the point-scalar multiplication from the privKey on the
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// generator point to get the pubkey.
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func (privKey *PrivKey) PubKey() cryptotypes.PubKey {
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_, pubkeyObject := secp256k1.PrivKeyFromBytes(secp256k1.S256(), privKey.Key)
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pk := pubkeyObject.SerializeCompressed()
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return &PubKey{Key: pk}
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}
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// Equals - you probably don't need to use this.
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// Runs in constant time based on length of the
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func (privKey *PrivKey) Equals(other cryptotypes.LedgerPrivKey) bool {
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return privKey.Type() == other.Type() && subtle.ConstantTimeCompare(privKey.Bytes(), other.Bytes()) == 1
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}
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func (privKey *PrivKey) Type() string {
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return keyType
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}
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// MarshalAmino overrides Amino binary marshalling.
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func (privKey PrivKey) MarshalAmino() ([]byte, error) {
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return privKey.Key, nil
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}
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// UnmarshalAmino overrides Amino binary marshalling.
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func (privKey *PrivKey) UnmarshalAmino(bz []byte) error {
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if len(bz) != PrivKeySize {
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return fmt.Errorf("invalid privkey size")
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}
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privKey.Key = bz
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return nil
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}
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// MarshalAminoJSON overrides Amino JSON marshalling.
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func (privKey PrivKey) MarshalAminoJSON() ([]byte, error) {
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// When we marshal to Amino JSON, we don't marshal the "key" field itself,
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// just its contents (i.e. the key bytes).
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return privKey.MarshalAmino()
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}
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// UnmarshalAminoJSON overrides Amino JSON marshalling.
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func (privKey *PrivKey) UnmarshalAminoJSON(bz []byte) error {
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return privKey.UnmarshalAmino(bz)
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}
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// GenPrivKey generates a new ECDSA private key on curve secp256k1 private key.
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// It uses OS randomness to generate the private key.
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func GenPrivKey() *PrivKey {
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return &PrivKey{Key: genPrivKey(crypto.CReader())}
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}
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// genPrivKey generates a new secp256k1 private key using the provided reader.
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func genPrivKey(rand io.Reader) []byte {
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var privKeyBytes [PrivKeySize]byte
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d := new(big.Int)
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for {
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privKeyBytes = [PrivKeySize]byte{}
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_, err := io.ReadFull(rand, privKeyBytes[:])
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if err != nil {
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panic(err)
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}
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d.SetBytes(privKeyBytes[:])
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// break if we found a valid point (i.e. > 0 and < N == curverOrder)
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isValidFieldElement := 0 < d.Sign() && d.Cmp(secp256k1.S256().N) < 0
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if isValidFieldElement {
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break
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}
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}
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return privKeyBytes[:]
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}
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var one = new(big.Int).SetInt64(1)
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// GenPrivKeyFromSecret hashes the secret with SHA2, and uses
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// that 32 byte output to create the private key.
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//
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// It makes sure the private key is a valid field element by setting:
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//
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// c = sha256(secret)
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// k = (c mod (n − 1)) + 1, where n = curve order.
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//
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// NOTE: secret should be the output of a KDF like bcrypt,
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// if it's derived from user input.
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func GenPrivKeyFromSecret(secret []byte) *PrivKey {
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secHash := sha256.Sum256(secret)
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// to guarantee that we have a valid field element, we use the approach of:
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// "Suite B Implementer’s Guide to FIPS 186-3", A.2.1
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// https://apps.nsa.gov/iaarchive/library/ia-guidance/ia-solutions-for-classified/algorithm-guidance/suite-b-implementers-guide-to-fips-186-3-ecdsa.cfm
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// see also https://github.com/golang/go/blob/0380c9ad38843d523d9c9804fe300cb7edd7cd3c/src/crypto/ecdsa/ecdsa.go#L89-L101
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fe := new(big.Int).SetBytes(secHash[:])
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n := new(big.Int).Sub(secp256k1.S256().N, one)
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fe.Mod(fe, n)
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fe.Add(fe, one)
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feB := fe.Bytes()
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privKey32 := make([]byte, PrivKeySize)
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// copy feB over to fixed 32 byte privKey32 and pad (if necessary)
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copy(privKey32[32-len(feB):32], feB)
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return &PrivKey{Key: privKey32}
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}
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//-------------------------------------
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var _ cryptotypes.PubKey = &PubKey{}
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var _ codec.AminoMarshaler = &PubKey{}
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// PubKeySize is comprised of 32 bytes for one field element
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// (the x-coordinate), plus one byte for the parity of the y-coordinate.
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const PubKeySize = 33
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// Address returns a Bitcoin style addresses: RIPEMD160(SHA256(pubkey))
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func (pubKey *PubKey) Address() crypto.Address {
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if len(pubKey.Key) != PubKeySize {
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panic("length of pubkey is incorrect")
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}
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sha := sha256.Sum256(pubKey.Key)
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hasherRIPEMD160 := ripemd160.New()
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hasherRIPEMD160.Write(sha[:]) // does not error
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return crypto.Address(hasherRIPEMD160.Sum(nil))
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}
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// Bytes returns the pubkey byte format.
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func (pubKey *PubKey) Bytes() []byte {
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return pubKey.Key
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}
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func (pubKey *PubKey) String() string {
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return fmt.Sprintf("PubKeySecp256k1{%X}", pubKey.Key)
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}
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func (pubKey *PubKey) Type() string {
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return keyType
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}
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func (pubKey *PubKey) Equals(other cryptotypes.PubKey) bool {
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return pubKey.Type() == other.Type() && bytes.Equal(pubKey.Bytes(), other.Bytes())
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}
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// MarshalAmino overrides Amino binary marshalling.
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func (pubKey PubKey) MarshalAmino() ([]byte, error) {
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return pubKey.Key, nil
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}
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// UnmarshalAmino overrides Amino binary marshalling.
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func (pubKey *PubKey) UnmarshalAmino(bz []byte) error {
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if len(bz) != PubKeySize {
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return errors.Wrap(errors.ErrInvalidPubKey, "invalid pubkey size")
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}
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pubKey.Key = bz
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return nil
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}
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// MarshalAminoJSON overrides Amino JSON marshalling.
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func (pubKey PubKey) MarshalAminoJSON() ([]byte, error) {
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// When we marshal to Amino JSON, we don't marshal the "key" field itself,
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// just its contents (i.e. the key bytes).
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return pubKey.MarshalAmino()
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}
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// UnmarshalAminoJSON overrides Amino JSON marshalling.
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func (pubKey *PubKey) UnmarshalAminoJSON(bz []byte) error {
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return pubKey.UnmarshalAmino(bz)
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}
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