From cb972ccd239a3c26a9a5a64959d359eba2f78db7 Mon Sep 17 00:00:00 2001 From: Jeremi Piotrowski Date: Fri, 20 Feb 2026 12:11:30 +0100 Subject: [PATCH] build_library: pcr: document how to rerun measurements in bash --- build_library/precompute_pcr.py | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/build_library/precompute_pcr.py b/build_library/precompute_pcr.py index d0c7e0804d..9e9908340c 100755 --- a/build_library/precompute_pcr.py +++ b/build_library/precompute_pcr.py @@ -49,6 +49,13 @@ PCR measurement details (SHA-256): PCR 9: Each source'd config file is measured as SHA-256(file_contents). The loaded kernel is measured as SHA-256(kernel_file_contents). + +Replay a single PCR from --print-hashes output using bash: + pcr=0000000000000000000000000000000000000000000000000000000000000000 + while read -r digest; do + pcr=$(printf '%s%s' "$pcr" "$digest" | xxd -r -p | sha256sum | cut -d' ' -f1) + done < <(jq -r '.["4"][].value' pcr_hashes.json) + echo "pcr4: $pcr" """ import argparse