mirror of
https://github.com/tpm2dev/tpm.dev.tutorials.git
synced 2024-11-24 14:52:11 +00:00
284 lines
8.4 KiB
Bash
Executable file
284 lines
8.4 KiB
Bash
Executable file
#!/bin/bash
|
|
|
|
PROG=${0##*/}
|
|
|
|
set -euo pipefail
|
|
shopt -s extglob
|
|
|
|
die() { echo "${PROG:+${PROG}: }$die_msg""$*" >&2 ; exit 1 ; }
|
|
info() { ((${VERBOSE:-0})) && echo "$@" >&2 ; return 0 ; }
|
|
|
|
function usage {
|
|
cat <<EOF
|
|
Usage: $PROG CIPHERTEXT OUT [POLICY-CMD [ARGS] [;] ...]
|
|
|
|
Decrypts the {CIPHERTEXT} file produced by {send-to-tpm}.
|
|
|
|
If {CIPHERTEXT}.tk.pem, {CIPHERTEXT}.tk.dpriv, {CIPHERTEXT}.tk.pub,
|
|
and {CIPHERTEXT}.tk.seed exist, then the "TK" method of encryption is
|
|
assumed. Otherwise the "EK" method of encryption is assumed.
|
|
|
|
See {send-to-tpm} for details of the two encryption-to-TPM methods
|
|
supported.
|
|
|
|
The plaintext is written to the {OUT} file.
|
|
|
|
If the sender asserted a policy, that policy must be given to {$PROG}
|
|
so it can execute and satisfy it.
|
|
|
|
Policies should be specified as a sequence of {tpm2 policy...}
|
|
commands, with all necessary arguments except for {--session}|{-S}
|
|
and {--policy}|{-L} options. Also, no need to include {tpm2
|
|
policycommandcode}, as that will get added. E.g.:
|
|
|
|
$ $PROG ./ekpub ./secret ./madecredential \\
|
|
tpm2 policypcr -l "sha256:0,1,2,3" -f pcrs
|
|
|
|
Options:
|
|
|
|
-h This help message.
|
|
-f Overwrite OUT-FILE.
|
|
-x Trace this script.
|
|
EOF
|
|
exit 1
|
|
}
|
|
|
|
force=false
|
|
while getopts +:hfx opt; do
|
|
case "$opt" in
|
|
h) usage 0;;
|
|
f) force=true;;
|
|
x) set -vx;;
|
|
*) usage;;
|
|
esac
|
|
done
|
|
shift $((OPTIND - 1))
|
|
|
|
(($# >= 2)) || usage
|
|
ciphertext_file=$1
|
|
out_file=$2
|
|
shift 2
|
|
|
|
[[ ! -f ${ciphertext_file:-} ]] && die "No ciphertext file given"
|
|
[[ -f ${out_file:-} ]] && $force && rm -f "$out_file"
|
|
[[ ! -f ${out_file:-} ]] || die "Plaintext file exists; use -f?"
|
|
|
|
d=
|
|
trap 'rm -rf "$d"' EXIT
|
|
d=$(mktemp -d)
|
|
|
|
use_tk=true
|
|
command_code=TPM2_CC_RSA_Decrypt
|
|
for i in dpriv pub seed; do
|
|
($use_tk && [[ -s ${ciphertext_file}.tk.$i ]]) || use_tk=false
|
|
done
|
|
$use_tk || command_code=TPM2_CC_ActivateCredential
|
|
|
|
# Execute a policy given as arguments.
|
|
#
|
|
# The first argument may be a command code; if given, then {tpm2}
|
|
# {policycommandcode} will be added to the given policy. The rest must be
|
|
# {tpm2_policy*} or {tpm2} {policy*} commands w/o any {--session}|{-c} or
|
|
# {--policy}|{-L} arguments, and multiple commands may be given separate by
|
|
# {';'}.
|
|
#
|
|
# E.g.,
|
|
#
|
|
# exec_policy TPM2_CC_ActivateCredential "$@"
|
|
# exec_policy tpm2 policypcr ... ';' tpm2 policysigned ...
|
|
function exec_policy {
|
|
local command_code=''
|
|
local add_commandcode=true
|
|
local has_policy=false
|
|
local -a cmd
|
|
|
|
if (($# > 0)) && [[ -z $1 || $1 = TPM2_CC_* ]]; then
|
|
command_code=$1
|
|
shift
|
|
fi
|
|
while (($# > 0)); do
|
|
has_policy=true
|
|
cmd=()
|
|
while (($# > 0)) && [[ $1 != ';' ]]; do
|
|
cmd+=("$1")
|
|
if ((${#cmd[@]} == 1)) && [[ ${cmd[0]} = tpm2_* ]]; then
|
|
cmd+=( --session "${d}/session.ctx"
|
|
--policy "${d}/policy")
|
|
elif ((${#cmd[@]} == 2)) && [[ ${cmd[0]} = tpm2 ]]; then
|
|
cmd+=( --session "${d}/session.ctx"
|
|
--policy "${d}/policy")
|
|
fi
|
|
shift
|
|
done
|
|
(($# > 0)) && shift
|
|
# Run the policy command in the temp dir. It -or the last command- must
|
|
# leave a file there named 'policy'.
|
|
"${cmd[@]}" 1>&2 \
|
|
|| die "unable to execute policy command: ${cmd[*]}"
|
|
[[ ${cmd[0]} = tpm2 ]] && ((${#cmd[@]} == 1)) \
|
|
&& die "Policy is incomplete"
|
|
[[ ${cmd[0]} = tpm2 && ${cmd[1]} = policycommandcode ]] \
|
|
&& add_commandcode=false
|
|
[[ ${cmd[0]} = tpm2_policycommandcode ]] \
|
|
&& add_commandcode=false
|
|
done
|
|
if $has_policy && $add_commandcode && [[ -n $command_code ]]; then
|
|
tpm2 policycommandcode \
|
|
--session "${d}/session.ctx" \
|
|
--policy "${d}/policy" \
|
|
"$command_code" 1>&2 \
|
|
|| die "unable to execute policy command: tpm2 policycommandcode $command_code"
|
|
fi
|
|
xxd -p -c 100 "${d}/policy"
|
|
}
|
|
|
|
# Compute the policyDigest of a given policy by executing it in a trial
|
|
# session.
|
|
function make_policyDigest {
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
tpm2 startauthsession --session "${d}/session.ctx"
|
|
exec_policy "$@"
|
|
}
|
|
|
|
# A well-known private key just for the TPM2_MakeCredential()-based encryption
|
|
# of secrets to TPMs. It was generated with:
|
|
# openssl genpkey -genparam \
|
|
# -algorithm EC \
|
|
# -out "${d}/ecp.pem" \
|
|
# -pkeyopt ec_paramgen_curve:secp384r1 \
|
|
# -pkeyopt ec_param_enc:named_curve
|
|
# openssl genpkey -paramfile "${d}/ecp.pem"
|
|
function wkpriv {
|
|
cat <<"EOF"
|
|
-----BEGIN PRIVATE KEY-----
|
|
MIG2AgEAMBAGByqGSM49AgEGBSuBBAAiBIGeMIGbAgEBBDAlMnCWue7CfXjNLibH
|
|
PTJrsOLUcoxqU3FLWYEWMI+HuPnzcwwl7SkKN6cpf4H3oQihZANiAAQ1pw6D5QVw
|
|
vymljYVDyrUriOet8zPB/9tq9XJ7A54qsVkaVufAuEJ6GIvD4xUZ27manMosJADS
|
|
aW2TLJkwxecRh2eTwPtSx2U32M2/yHeuWRV/0juiIozefPsTAlHAi3E=
|
|
-----END PRIVATE KEY-----
|
|
EOF
|
|
}
|
|
|
|
# Get the EK handle
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
tpm2 flushcontext --saved-session 1>&2
|
|
tpm2 createek \
|
|
--key-algorithm rsa \
|
|
--ek-context "${d}/ek.ctx" \
|
|
--public "${d}/ek.pub" \
|
|
|| die "tpm2: unable to create ek object"
|
|
|
|
# Make policyDigest
|
|
(($# > 0)) && make_policyDigest "$command_code" "$@"
|
|
|
|
# Create empty auth session for EK
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
tpm2 startauthsession --session "${d}/sessionek.ctx" --policy-session
|
|
tpm2 policysecret --session "${d}/sessionek.ctx" --object-context endorsement
|
|
|
|
# Execute and satisfy the policy for the TK or WK
|
|
function auth {
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
tpm2 startauthsession \
|
|
--session "${d}/session.ctx" \
|
|
--policy-session
|
|
# exec_policy will {die} if we fail to satisfy the policy
|
|
exec_policy "$command_code" "$@"
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
}
|
|
|
|
if $use_tk; then
|
|
# attempt to load the secret wrapping key into our TPM
|
|
# as a transient object
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
|
|
info "tpm2: Importing duplicate transport key"
|
|
tpm2 import \
|
|
--parent-context "${d}/ek.ctx" \
|
|
--parent-auth "session:${d}/sessionek.ctx" \
|
|
--key-algorithm rsa \
|
|
--input "${ciphertext_file}.tk.dpriv" \
|
|
--seed "${ciphertext_file}.tk.seed" \
|
|
--public "${ciphertext_file}.tk.pub" \
|
|
--private "${d}/tk.priv" \
|
|
|| die "tpm2: unable to import duplicate transport key object"
|
|
|
|
warn "tpm2: Loading duplicate transport key"
|
|
tpm2 flushcontext --transient-object
|
|
tpm2 flushcontext --loaded-session
|
|
tpm2 startauthsession --session "${d}/sessionek.ctx" --policy-session
|
|
tpm2 policysecret --session "${d}/sessionek.ctx" --object-context endorsement
|
|
tpm2 load \
|
|
--parent-context "${d}/ek.ctx" \
|
|
--auth "session:${d}/sessionek.ctx" \
|
|
--key-context "${d}/tk.ctx" \
|
|
--public "${ciphertext_file}.tk.pub" \
|
|
--private "${d}/tk.priv" \
|
|
|| die "tpm2: unable to load duplicate transport key object"
|
|
|
|
warn "tpm2: Decrypting with TK"
|
|
if (($# > 0)); then
|
|
auth "$@"
|
|
tpm2 rsadecrypt \
|
|
--auth "session:${d}/session.ctx" \
|
|
--key-context "${d}/tk.ctx" \
|
|
--output "${out_file}" \
|
|
"${ciphertext_file}" \
|
|
|| die "tpm2: unable to decrypt with transport key"
|
|
else
|
|
tpm2 rsadecrypt \
|
|
--key-context "${d}/tk.ctx" \
|
|
--output "${out_file}" \
|
|
"${ciphertext_file}" \
|
|
|| die "tpm2: unable to decrypt with transport key"
|
|
fi
|
|
else
|
|
# Load the WK for use as the activation object for
|
|
# TPM2_ActivateCredential():
|
|
tpm2 flushcontext --transient-object 1>&2
|
|
tpm2 flushcontext --loaded-session 1>&2
|
|
wkpriv > "${d}/wkpriv.pem"
|
|
attrs='sign'
|
|
adminwithpolicy=
|
|
if (($# > 0)); then
|
|
attrs='adminwithpolicy|sign'
|
|
adminwithpolicy=true
|
|
fi
|
|
if tpm2 loadexternal \
|
|
--hierarchy n \
|
|
--key-algorithm ecc \
|
|
--private "${d}/wkpriv.pem" \
|
|
${adminwithpolicy:+--policy "${d}/policy"} \
|
|
--attributes "$attrs" \
|
|
--key-context "${d}/wk.ctx" 1>&2; then
|
|
true
|
|
else
|
|
stat=$?
|
|
echo "ERROR: Failed to load WK: $?" 1>&2
|
|
exit $stat
|
|
fi
|
|
|
|
# If a policy was given to execute, create a policy session and execute
|
|
# and satisfy the policy:
|
|
activatecredential_args=()
|
|
if (($# > 0)); then
|
|
activatecredential_args+=(--credentialedkey-auth session:"${d}/session.ctx")
|
|
auth "$@"
|
|
fi
|
|
|
|
# Finally, ActivateCredential
|
|
tpm2 activatecredential \
|
|
--credentialedkey-context "${d}/wk.ctx" \
|
|
"${activatecredential_args[@]}" \
|
|
--credentialkey-context "${d}/ek.ctx" \
|
|
--credentialkey-auth session:"${d}/sessionek.ctx" \
|
|
--credential-blob "$ciphertext_file" \
|
|
--certinfo-data "$out_file" > /dev/null \
|
|
|| die "could not decrypt using TPM2_ActivateCredential()"
|
|
fi
|