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39 lines
964 B
39 lines
964 B
package secp256r1
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import (
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"crypto/ecdsa"
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"crypto/elliptic"
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"errors"
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"math/big"
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"github.com/ethereum/go-ethereum/common"
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)
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var (
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secp256k1halfN = new(big.Int).Div(elliptic.P256().Params().N, big.NewInt(2))
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)
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// Verifies the given signature (r, s) for the given hash and public key (x, y).
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func Verify(hash []byte, r, s, x, y *big.Int) ([]byte, error) {
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// Create the public key format
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publicKey := newPublicKey(x, y)
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if publicKey == nil {
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return nil, errors.New("invalid public key coordinates")
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}
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if checkMalleability(s) {
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return nil, errors.New("malleability issue")
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}
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// Verify the signature with the public key and return 1 if it's valid, 0 otherwise
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if ok := ecdsa.Verify(publicKey, hash, r, s); ok {
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return common.LeftPadBytes(common.Big1.Bytes(), 32), nil
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}
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return common.LeftPadBytes(common.Big0.Bytes(), 32), nil
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}
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// Check the malleability issue
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func checkMalleability(s *big.Int) bool {
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return s.Cmp(secp256k1halfN) > 0
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}
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