48 lines
1.4 KiB
Go
48 lines
1.4 KiB
Go
package opentimestamps
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import (
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"bytes"
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"fmt"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/btcsuite/btcd/wire"
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)
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type Bitcoin interface {
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GetBlockHash(height int64) (*chainhash.Hash, error)
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GetBlockHeader(hash *chainhash.Hash) (*wire.BlockHeader, error)
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}
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// Verify validates sequence of operations that starts with digest and ends on a Bitcoin attestation against
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// an actual Bitcoin block, as given by the provided Bitcoin interface.
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func (seq Sequence) Verify(bitcoin Bitcoin, digest []byte) (*wire.MsgTx, error) {
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if len(seq) == 0 {
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return nil, fmt.Errorf("empty sequence")
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}
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att := seq[len(seq)-1]
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if att.Attestation == nil || att.BitcoinBlockHeight == 0 {
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return nil, fmt.Errorf("sequence doesn't include a bitcoin attestation")
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}
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blockHash, err := bitcoin.GetBlockHash(int64(att.BitcoinBlockHeight))
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if err != nil {
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return nil, fmt.Errorf("failed to get block %d hash: %w", att.BitcoinBlockHeight, err)
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}
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blockHeader, err := bitcoin.GetBlockHeader(blockHash)
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if err != nil {
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return nil, fmt.Errorf("failed to get block %s header: %w", blockHash, err)
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}
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merkleRoot := blockHeader.MerkleRoot[:]
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result, tx := seq.Compute(digest)
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if !bytes.Equal(result, merkleRoot) {
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return nil, fmt.Errorf("sequence result '%x' doesn't match the bitcoin merkle root for block %d: %x",
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result, att.BitcoinBlockHeight, merkleRoot)
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}
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return tx, nil
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}
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