move pdf generation code from command to separate package
This commit is contained in:
307
cmd/ots/pdf.go
307
cmd/ots/pdf.go
@@ -1,20 +1,11 @@
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package main
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import (
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"bytes"
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"log/slog"
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"os"
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"path/filepath"
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"strings"
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"time"
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"git.intruders.space/public/opentimestamps"
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"git.intruders.space/public/opentimestamps/ots"
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"git.intruders.space/public/opentimestamps/verifyer"
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"github.com/jung-kurt/gofpdf"
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"git.intruders.space/public/opentimestamps/pdf"
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"github.com/spf13/cobra"
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)
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@@ -64,10 +55,6 @@ func runPdfCmd(cmd *cobra.Command, args []string) {
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os.Exit(1)
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}
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// Compute the file digest
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fileDigest := sha256.Sum256(fileData)
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slog.Debug("Computed file digest", "digest", hex.EncodeToString(fileDigest[:]))
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// Read and parse the OTS file
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otsData, err := os.ReadFile(otsPath)
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if err != nil {
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@@ -81,294 +68,32 @@ func runPdfCmd(cmd *cobra.Command, args []string) {
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os.Exit(1)
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}
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// Check if the digests match
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if !bytes.Equal(fileDigest[:], timestampFile.Digest) {
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slog.Warn("Warning: File digest doesn't match timestamp digest",
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"file_digest", hex.EncodeToString(fileDigest[:]),
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"timestamp_digest", hex.EncodeToString(timestampFile.Digest))
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// Set up PDF options from command line flags
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options := pdf.CertificateOptions{
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Title: pdfTitle,
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Comment: pdfComment,
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IncludeContent: pdfIncludeContent,
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EsploraURL: pdfEsploraURL,
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}
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// Extract Bitcoin attestations
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bitcoinSeqs := timestampFile.GetBitcoinAttestedSequences()
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if len(bitcoinSeqs) == 0 {
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slog.Warn("No Bitcoin attestations found in timestamp, certificate will be for pending timestamps")
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}
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// Create Bitcoin interface for block time lookup
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bitcoin := verifyer.NewEsploraClient(pdfEsploraURL, 30*time.Second)
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slog.Info("Using Esplora API for block information", "url", pdfEsploraURL)
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// Generate the PDF
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err = generateVerificationPDF(
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outputPath,
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pdfBuffer, err := pdf.GenerateCertificate(
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filePath,
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fileData,
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fileDigest[:],
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timestampFile,
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bitcoinSeqs,
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bitcoin,
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options,
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)
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if err != nil {
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slog.Error("Failed to generate PDF", "error", err)
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os.Exit(1)
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}
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// Write to file
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err = pdf.WriteToFile(pdfBuffer, outputPath)
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if err != nil {
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slog.Error("Failed to write PDF to file", "file", outputPath, "error", err)
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os.Exit(1)
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}
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slog.Info("PDF certificate generated successfully", "file", outputPath)
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}
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func generateVerificationPDF(outputPath, filePath string, fileData []byte, fileDigest []byte,
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timestamp *ots.File, bitcoinSeqs []ots.Sequence, bitcoin verifyer.Bitcoin) error {
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// Create a new PDF
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pdf := gofpdf.New("P", "mm", "A4", "")
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pdf.SetTitle(pdfTitle, true)
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pdf.SetAuthor("OpenTimestamps", true)
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pdf.SetCreator("OpenTimestamps CLI", true)
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// Set margins
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pdf.SetMargins(25, 25, 25)
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pdf.SetAutoPageBreak(true, 25)
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// Add first page - Certificate
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pdf.AddPage()
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// Title
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pdf.SetFont("Helvetica", "B", 24)
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pdf.CellFormat(0, 12, pdfTitle, "", 1, "C", false, 0, "")
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pdf.Ln(10)
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// Timestamp information section
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pdf.SetFont("Helvetica", "B", 18)
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pdf.CellFormat(0, 10, "Timestamp Information", "", 1, "L", false, 0, "")
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pdf.Ln(5)
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "Filename:", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.CellFormat(0, 8, filepath.Base(filePath), "", 1, "L", false, 0, "")
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pdf.Ln(2)
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// Timestamp date
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pdf.SetFont("Helvetica", "B", 12)
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if len(bitcoinSeqs) > 0 {
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// Find the earliest Bitcoin attestation
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var earliestHeight uint64
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var earliestBlockTime time.Time
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for _, seq := range bitcoinSeqs {
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att := seq.GetAttestation()
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if earliestHeight == 0 || att.BitcoinBlockHeight < earliestHeight {
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earliestHeight = att.BitcoinBlockHeight
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// Fetch the block time from the blockchain
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blockHash, err := bitcoin.GetBlockHash(int64(att.BitcoinBlockHeight))
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if err == nil {
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blockHeader, err := bitcoin.GetBlockHeader(blockHash)
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if err == nil {
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earliestBlockTime = time.Unix(int64(blockHeader.Timestamp.Unix()), 0)
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}
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}
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}
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}
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// Show Bitcoin timestamp
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pdf.CellFormat(0, 8, "Timestamp Created:", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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if !earliestBlockTime.IsZero() {
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// If we successfully retrieved the block time, display it
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pdf.CellFormat(0, 8, fmt.Sprintf("Bitcoin Block #%d (%s)",
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earliestHeight, earliestBlockTime.Format("Jan 02, 2006 15:04:05 UTC")),
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"", 1, "L", false, 0, "")
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} else {
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// Fallback to just showing the block height
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pdf.CellFormat(0, 8, fmt.Sprintf("Bitcoin Block #%d", earliestHeight), "", 1, "L", false, 0, "")
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}
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} else {
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// Pending attestation
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pdf.CellFormat(0, 8, "Status:", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.CellFormat(0, 8, "Pending confirmation in the Bitcoin blockchain", "", 1, "L", false, 0, "")
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}
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pdf.Ln(2)
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// File hash
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "File SHA-256 Digest:", "", 1, "L", false, 0, "")
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pdf.SetFont("Courier", "", 10)
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pdf.CellFormat(0, 8, hex.EncodeToString(fileDigest), "", 1, "L", false, 0, "")
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pdf.Ln(5)
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// Include comment if provided
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if pdfComment != "" {
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "Comment:", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.MultiCell(0, 8, pdfComment, "", "L", false)
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pdf.Ln(5)
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}
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// Include file content if requested and looks like text
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if pdfIncludeContent && isTextFile(fileData) && len(fileData) < 5000 {
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "File Content:", "", 1, "L", false, 0, "")
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pdf.SetFont("Courier", "", 10)
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content := string(fileData)
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content = strings.ReplaceAll(content, "\r\n", "\n")
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pdf.MultiCell(0, 5, content, "", "L", false)
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pdf.Ln(5)
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}
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// Add Bitcoin transaction information for each attestation
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if len(bitcoinSeqs) > 0 {
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pdf.SetFont("Helvetica", "B", 18)
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pdf.CellFormat(0, 10, "Bitcoin Attestations", "", 1, "L", false, 0, "")
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pdf.Ln(5)
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for i, seq := range bitcoinSeqs {
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att := seq.GetAttestation()
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pdf.SetFont("Helvetica", "B", 14)
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pdf.CellFormat(0, 8, fmt.Sprintf("Attestation #%d", i+1), "", 1, "L", false, 0, "")
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pdf.Ln(2)
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// Get block details
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blockHash, err := bitcoin.GetBlockHash(int64(att.BitcoinBlockHeight))
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blockTime := "Unknown"
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if err == nil {
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blockHeader, err := bitcoin.GetBlockHeader(blockHash)
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if err == nil {
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blockTime = blockHeader.Timestamp.Format("Jan 02, 2006 15:04:05 UTC")
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}
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}
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "Bitcoin Block Height:", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.CellFormat(0, 8, fmt.Sprintf("%d", att.BitcoinBlockHeight), "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "Block Time:", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.CellFormat(0, 8, blockTime, "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "Block Hash:", "", 1, "L", false, 0, "")
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pdf.SetFont("Courier", "", 10)
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if blockHash != nil {
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pdf.CellFormat(0, 8, blockHash.String(), "", 1, "L", false, 0, "")
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} else {
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pdf.CellFormat(0, 8, "Unable to retrieve", "", 1, "L", false, 0, "")
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}
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// In a full implementation, we would show the Bitcoin merkle root and transaction ID
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// This would require additional API calls to get that information
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// Show operations sequence
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pdf.SetFont("Helvetica", "B", 12)
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pdf.CellFormat(0, 8, "Verification Operations:", "", 1, "L", false, 0, "")
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pdf.SetFont("Courier", "", 10)
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// Format the operations
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var operationsText string
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merkleRoot, _ := seq.Compute(timestamp.Digest)
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operationsText += fmt.Sprintf("Starting with digest: %s\n", hex.EncodeToString(timestamp.Digest))
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for j, inst := range seq {
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if inst.Operation != nil {
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if inst.Operation.Binary {
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operationsText += fmt.Sprintf("%d. %s %s\n", j+1, inst.Operation.Name, hex.EncodeToString(inst.Argument))
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} else {
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operationsText += fmt.Sprintf("%d. %s\n", j+1, inst.Operation.Name)
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}
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}
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}
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operationsText += fmt.Sprintf("\nResulting merkle root: %s\n", hex.EncodeToString(merkleRoot))
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pdf.MultiCell(0, 5, operationsText, "", "L", false)
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pdf.Ln(5)
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}
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}
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// Add second page - Verification Instructions
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pdf.AddPage()
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pdf.SetFont("Helvetica", "B", 18)
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pdf.CellFormat(0, 10, "Verification Instructions", "", 1, "L", false, 0, "")
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pdf.Ln(5)
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// Instructions
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addVerificationInstructions(pdf)
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// Save the PDF
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return pdf.OutputFileAndClose(outputPath)
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}
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func addVerificationInstructions(pdf *gofpdf.Fpdf) {
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pdf.SetFont("Helvetica", "B", 14)
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pdf.CellFormat(0, 8, "1. Compute the SHA-256 digest of your file", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.MultiCell(0, 6, `To verify this timestamp, first compute the SHA-256 digest of your original file. You can use various tools for this:
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- On Linux/macOS: Use the command "shasum -a 256 filename"
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- On Windows: Use tools like PowerShell's "Get-FileHash" or third-party tools
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- Online: Various websites can calculate file hashes, but only use trusted sources for sensitive files
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Verify that the digest matches the one shown in this certificate.`, "", "L", false)
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pdf.Ln(5)
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pdf.SetFont("Helvetica", "B", 14)
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pdf.CellFormat(0, 8, "2. Verify the operations sequence", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.MultiCell(0, 6, `The operations sequence shown in this certificate transforms the file digest into a value that was stored in the Bitcoin blockchain. To verify manually:
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- Start with the file's SHA-256 digest
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- Apply each operation in sequence as shown in the certificate
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- For "append" operations, add the shown bytes to the end of the current value
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- For "prepend" operations, add the shown bytes to the beginning of the current value
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- For "sha256" operations, compute the SHA-256 hash of the current value
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- The final result should match the merkle root shown in the certificate`, "", "L", false)
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pdf.Ln(5)
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pdf.SetFont("Helvetica", "B", 14)
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pdf.CellFormat(0, 8, "3. Verify the Bitcoin attestation", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.MultiCell(0, 6, `For full verification, check that the merkle root was recorded in the Bitcoin blockchain:
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- Find the Bitcoin block at the height shown in the certificate
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- The block's merkle root or transaction should contain the computed value
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- You can use block explorers like blockstream.info or blockchain.com
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- The timestamp is confirmed when the merkle root appears in the blockchain`, "", "L", false)
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pdf.Ln(5)
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pdf.SetFont("Helvetica", "B", 14)
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pdf.CellFormat(0, 8, "4. Use the OpenTimestamps verifier", "", 1, "L", false, 0, "")
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pdf.SetFont("Helvetica", "", 12)
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pdf.MultiCell(0, 6, `For easier verification, use the OpenTimestamps verification tools:
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- Command line: Use "ots verify <file> <file.ots>"
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- Online: Visit https://opentimestamps.org and upload your file and .ots timestamp
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- The tools will perform all verification steps automatically`, "", "L", false)
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// Add footer with generation time
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pdf.Ln(10)
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pdf.SetFont("Helvetica", "I", 10)
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pdf.CellFormat(0, 6, fmt.Sprintf("Certificate generated at: %s", time.Now().Format(time.RFC3339)), "", 1, "C", false, 0, "")
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pdf.CellFormat(0, 6, "OpenTimestamps - https://opentimestamps.org", "", 1, "C", false, 0, "")
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}
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// isTextFile tries to determine if a file is likely to be text
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func isTextFile(data []byte) bool {
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// Simple heuristic: if the file doesn't contain too many non-printable characters,
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// it's probably text
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nonPrintable := 0
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for _, b := range data {
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if (b < 32 || b > 126) && b != 9 && b != 10 && b != 13 {
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nonPrintable++
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}
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}
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// Allow up to 1% non-printable characters
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return nonPrintable <= len(data)/100
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}
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Reference in New Issue
Block a user