% tpm2_pcrread(1) tpm2-tools | General Commands Manual

NAME

tpm2_pcrread(1) - List PCR values.

SYNOPSIS

tpm2_pcrread [OPTIONS] PCR_LIST_OR_ALG

DESCRIPTION

tpm2_pcrread(1) - Displays PCR values. Without any arguments, tpm2_pcrread(1) outputs all PCRs and their hash banks. One can use specify the hash algorithm or a pcr list as an argument to filter the output.

To only output PCR banks with a given algorithm, specify the hashing algorithm as the argument. Algorithms should follow the "formatting standards", see section "Algorithm Specifiers". Also, see section "Supported Hash Algorithms" for a list of supported hash algorithms.

To output a list of PCR banks (sha1, sha256, etc) and ids (0, 1, 2 etc) specify a PCR selection list as the argument as specified via section "PCR Bank Specifiers".

Also read NOTES section below.

Output is written in a YAML format to stdout, with each algorithm followed by a PCR index and its value. As a simple example assume just sha1 and sha256 support and only 1 PCR. The output would be:

$ tpm2_pcrread sha1:0+sha256:0
sha1 :
  0  : 0000000000000000000000000000000000000003
sha256 :
  0  : 0000000000000000000000000000000000000000000000000000000000000003

OPTIONS

  • -o, --output=FILE:

    The output file to write the PCR values in binary format, optional.

PCR output file format specifiers Default is 'values'.

common options

common tcti options

PCR bank specifiers

supported hash algorithms

algorithm specifiers

EXAMPLES

Display all PCR values

tpm2_pcrread

Display the PCR values with a specified bank

tpm2_pcrread sha1

Display the PCR values with specified banks and store in a file

tpm2_pcrread -o pcrs sha1:16,17,18+sha256:16,17,18

Display the supported PCR bank algorithms and exit

tpm2_pcrread

NOTES

The maximum number of PCR that can be dumped at once is associated with the maximum length of a bank.

On most TPMs, it means that this tool can dump up to 24 PCRs at once.

returns

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