Merge pull request #4 from tuxlifan/upyx-b2sum

Include the b2sum for the original data in the generated PDF file.

Author: Intra2net AG

paperbackup-verify.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/bash
+
+# USAGE: paperbackup-verify.sh backup.pdf
+#   where backup.pdf should be the pdf created with paperbackup.py
+
+RESTOREPROG=$(dirname $0)/paperrestore.sh
+
+bPDF=$( $RESTOREPROG $1 | sha256sum | cut -d ' ' -f 1)
+bEmbedded=$(pdftotext $1 - | grep sha256sum -A1 | tail -1 | tr -d '\n')
+
+if [ "x$bPDF" == "x$bEmbedded" ]; then
+    echo "sha256sums MATCH :-)"
+    echo
+    exit 0
+else
+    echo "Creating diff:"
+    $RESTOREPROG $1 | diff ${1%.*} -
+    diffret=$?
+    echo
+    if [ $diffret -ne 0 ]; then
+        echo "diff and sha256sums do NOT match!"
+        echo "restored sha256sum from PDF: " $bPDF
+        echo "original sha256sum embedded: " $bEmbedded
+        echo
+        exit 11
+    else
+        echo "diff matches but sha256sum is missing."
+        echo "restored sha256sum from PDF: " $bPDF
+        echo "original sha256sum embedded: " $bEmbedded
+        echo
+        exit 1
+    fi
+fi

paperbackup.py

@@ -171,6 +171,9 @@ def finish_page(pdf, canv, pageno):
 
     chksumlines.append(line)
 
+# we also want a checksum which the restored file should match
+checksum = hashlib.sha256(bytes(ascdata, 'utf8')).hexdigest()
+
 # add some documentation around the plaintest
 outlines=[]
 coldoc=" "*splitat
@@ -179,6 +182,9 @@ def finish_page(pdf, canv, pageno):
 outlines.extend(chksumlines)
 outlines.append("")
 outlines.append("")
+outlines.append("sha256sum of input file:")
+outlines.append("%s"%checksum)
+outlines.append("")
 outlines.append("")
 outlines.append("--")
 outlines.append("Created with paperbackup.py")
@@ -216,3 +222,6 @@ def finish_page(pdf, canv, pageno):
 
 os.remove(temp_text_path)
 os.remove(temp_barcode_path)
+
+print("Please now verify that the output can be restored by calling:")
+print("paperbackup-verify.sh {}.pdf".format(just_filename))