Switch from blake2b to sha256 checksum

Future proof by popularity.

Author: tuxlifan

paperbackup-verify.sh

@@ -4,30 +4,29 @@
 #   where backup.pdf should be the pdf created with paperbackup.py
 
 RESTOREPROG=$(dirname $0)/paperrestore.sh
-PAPERB2SUMPROG="$(dirname $0)/paperbackup.py --b2sum"
 
-rPDF=$( $RESTOREPROG $1 )
-
-bPDF=$(echo "$rPDF" | $PAPERB2SUMPROG )
-bEmbedded=$(pdftotext $1 - | grep b2sum -A2 | tail -2 | tr -d '\n')
+bPDF=$( $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 "b2sums MATCH :-)"
+    echo "sha256sums MATCH :-)"
     echo
     exit 0
 else
     echo "Creating diff:"
-    echo "$rPDF" | diff ${1%.*} -
+    $RESTOREPROG $1 | diff ${1%.*} -
     diffret=$?
     echo
     if [ $diffret -ne 0 ]; then
-        echo "diff and b2sums do NOT match!"
-        echo "restored b2sum from PDF: " $bPDF
-        echo "original b2sum embedded: " $bEmbedded
+        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 b2sum is missing."
+        echo "diff matches but sha256sum is missing."
+        echo "restored sha256sum from PDF: " $bPDF
+        echo "original sha256sum embedded: " $bEmbedded
         echo
         exit 1
     fi

paperbackup.py

@@ -35,7 +35,6 @@
 import qrencode
 from tempfile import mkstemp
 from datetime import datetime
-from shutil import which
 from PIL import Image
 from pyx import *
 
@@ -71,15 +70,6 @@ def finish_page(pdf, canv, pageno):
 
 # main code
 
-if sys.argv[1] == "--b2sum":
-    if len(sys.argv) > 2:
-        with open(sys.argv[2], 'r') as ifile:
-            data = ''.join(ifile.readlines())
-    else:
-        data = ''.join(sys.stdin.readlines())
-    print(hashlib.blake2b(bytes(data, 'utf8')).hexdigest())
-    sys.exit(0)
-
 if len(sys.argv) != 2:
     raise RuntimeError('Usage {} FILENAME.asc'.format(sys.argv[0]))
 
@@ -182,7 +172,7 @@ def finish_page(pdf, canv, pageno):
     chksumlines.append(line)
 
 # we also want a checksum which the restored file should match
-b2sum = hashlib.blake2b(bytes(ascdata, 'utf8')).hexdigest()
+checksum = hashlib.sha256(bytes(ascdata, 'utf8')).hexdigest()
 
 # add some documentation around the plaintest
 outlines=[]
@@ -192,9 +182,8 @@ def finish_page(pdf, canv, pageno):
 outlines.extend(chksumlines)
 outlines.append("")
 outlines.append("")
-outlines.append("b2sum of input file (split over 2 lines):")
-outlines.append("%s"%b2sum[:64])
-outlines.append("%s"%b2sum[64:])
+outlines.append("sha256sum of input file:")
+outlines.append("%s"%checksum)
 outlines.append("")
 outlines.append("")
 outlines.append("--")