forked from TrueCloudLab/frostfs-sdk-go
79 lines
1.8 KiB
Go
79 lines
1.8 KiB
Go
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package neofsecdsa
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"crypto/sha256"
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"crypto/sha512"
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"math/big"
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"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
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)
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// PublicKey implements neofscrypto.PublicKey based on ECDSA.
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//
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// Supported schemes:
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// - neofscrypto.ECDSA_SHA512 (default)
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// - neofscrypto.ECDSA_DETERMINISTIC_SHA256
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type PublicKey struct {
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deterministic bool
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key ecdsa.PublicKey
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}
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// MakeDeterministic makes PublicKey to use Deterministic ECDSA scheme
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// (see neofscrypto.ECDSA_DETERMINISTIC_SHA256). By default,
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// neofscrypto.ECDSA_SHA512 is used.
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func (x *PublicKey) MakeDeterministic() {
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x.deterministic = true
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}
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// Decode decodes compressed binary representation of the PublicKey.
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//
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// See also Signer.EncodePublicKey.
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func (x *PublicKey) Decode(data []byte) error {
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pub, err := keys.NewPublicKeyFromBytes(data, elliptic.P256())
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if err != nil {
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return err
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}
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x.key = (ecdsa.PublicKey)(*pub)
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return nil
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}
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// similar to elliptic.Unmarshal but without IsOnCurve check.
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func unmarshalXY(data []byte) (x *big.Int, y *big.Int) {
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if len(data) != 65 {
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return
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} else if data[0] != 4 { // uncompressed form
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return
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}
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p := elliptic.P256().Params().P
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x = new(big.Int).SetBytes(data[1:33])
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y = new(big.Int).SetBytes(data[33:])
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if x.Cmp(p) >= 0 || y.Cmp(p) >= 0 {
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x, y = nil, nil
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}
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return
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}
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// Verify verifies data signature calculated by algorithm depending on
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// PublicKey state:
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// - Deterministic ECDSA with SHA-256 hashing if MakeDeterministic called
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// - ECDSA with SHA-512 hashing, otherwise
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func (x PublicKey) Verify(data, signature []byte) bool {
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if x.deterministic {
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h := sha256.Sum256(data)
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return (*keys.PublicKey)(&x.key).Verify(signature, h[:])
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}
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h := sha512.Sum512(data)
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r, s := unmarshalXY(signature)
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return r != nil && s != nil && ecdsa.Verify(&x.key, h[:], r, s)
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}
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