From e52ac3afa0f25f2dfd3e7dde6e1c7c311636f5f0 Mon Sep 17 00:00:00 2001 From: Daniel Kahn Gillmor Date: Mon, 25 May 2009 15:02:58 -0400 Subject: [PATCH] break out signature timestamp from key timestamp, allow them to be set independently. --- man/man1/pem2openpgp.1 | 10 ++++++- src/share/keytrans | 59 ++++++++++++++++++++++++++---------------- 2 files changed, 45 insertions(+), 24 deletions(-) diff --git a/man/man1/pem2openpgp.1 b/man/man1/pem2openpgp.1 index 45fd1ee..5622bd7 100644 --- a/man/man1/pem2openpgp.1 +++ b/man/man1/pem2openpgp.1 @@ -29,11 +29,19 @@ The following environment variables influence the behavior of .ti 3 \fBPEM2OPENPGP_TIMESTAMP\fP controls the timestamp (measured in seconds since the UNIX epoch) indicated as the creation time (a.k.a -"not valid before") of the generated certificate. By default, +"not valid before") of the generated certificate (self-signature) and +the key itself. By default, .Nm uses the current time. .Pp .ti 3 +\fBPEM2OPENPGP_KEY_TIMESTAMP\fP controls the timestamp (measured in +seconds since the UNIX epoch) indicated as the creation time of just +the key itself (not the self-signature). By default, +.Nm +uses the value from PEM2OPENPGP_TIMESTAMP. +.Pp +.ti 3 \fBPEM2OPENPGP_USAGE_FLAGS\fP should contain a comma-separated list of valid OpenPGP usage flags (see section 5.2.3.21 of RFC 4880 for what these mean). The available choices are: certify, sign, encrypt_comms, diff --git a/src/share/keytrans b/src/share/keytrans index c47ccdc..3638eae 100755 --- a/src/share/keytrans +++ b/src/share/keytrans @@ -368,12 +368,12 @@ sub read_mpi { # FIXME: genericize these to accept either RSA or DSA keys: sub make_rsa_pub_key_body { my $key = shift; - my $timestamp = shift; + my $key_timestamp = shift; my ($n, $e) = $key->get_key_parameters(); return - pack('CN', 4, $timestamp). + pack('CN', 4, $key_timestamp). pack('C', $asym_algos->{rsa}). mpi_pack($n). mpi_pack($e); @@ -381,7 +381,7 @@ sub make_rsa_pub_key_body { sub make_rsa_sec_key_body { my $key = shift; - my $timestamp = shift; + my $key_timestamp = shift; # we're not using $a and $b, but we need them to get to $c. my ($n, $e, $d, $p, $q) = $key->get_key_parameters(); @@ -400,7 +400,7 @@ sub make_rsa_sec_key_body { # with modular_multi_inverse. return - pack('CN', 4, $timestamp). + pack('CN', 4, $key_timestamp). pack('C', $asym_algos->{rsa}). mpi_pack($n). mpi_pack($e). @@ -412,9 +412,9 @@ sub make_rsa_sec_key_body { # expects an RSA key (public or private) and a timestamp sub fingerprint { my $key = shift; - my $timestamp = shift; + my $key_timestamp = shift; - my $rsabody = make_rsa_pub_key_body($key, $timestamp); + my $rsabody = make_rsa_pub_key_body($key, $key_timestamp); return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody); } @@ -436,9 +436,14 @@ sub pem2openpgp { die "key does not check"; } + # strong assertion of identity is the default (for a self-sig): + my $certtype = $sig_types->{positive_certification}; + if (defined $args->{certification_type}) { + $certtype = $args->{certification_type} + 0; + } + my $version = pack('C', 4); - # strong assertion of identity: - my $sigtype = pack('C', $sig_types->{positive_certification}); + my $sigtype = pack('C', $certtype); # RSA my $pubkey_algo = pack('C', $asym_algos->{rsa}); # SHA1 @@ -449,17 +454,24 @@ sub pem2openpgp { # this script more than once against the same key (because the # timestamps will differ). How can we prevent this? - # this environment variable (if set) overrides the current time, to - # be able to create a standard key? If we read the key from a file + # this argument (if set) overrides the current time, to + # be able to create a standard key. If we read the key from a file # instead of stdin, should we use the creation time on the file? - my $timestamp = 0; - if (defined $args->{timestamp}) { - $timestamp = ($args->{timestamp} + 0); + my $sig_timestamp = 0; + if (defined $args->{sig_timestamp}) { + $sig_timestamp = ($args->{sig_timestamp} + 0); } else { - $timestamp = time(); + $sig_timestamp = time(); + } + my $key_timestamp = $sig_timestamp; + if (defined $args->{key_timestamp}) { + $key_timestamp = ($args->{key_timestamp} + 0); + } + if ($key_timestamp > $sig_timestamp) { + die "key timestamp must not be later than signature timestamp"; } - my $creation_time_packet = pack('CCN', 5, $subpacket_types->{sig_creation_time}, $timestamp); + my $creation_time_packet = pack('CCN', 5, $subpacket_types->{sig_creation_time}, $sig_timestamp); my $flags = 0; @@ -542,8 +554,8 @@ sub pem2openpgp { $subpacket_octets. $subpackets_to_be_hashed; - my $pubkey = make_rsa_pub_key_body($rsa, $timestamp); - my $seckey = make_rsa_sec_key_body($rsa, $timestamp); + my $pubkey = make_rsa_pub_key_body($rsa, $key_timestamp); + my $seckey = make_rsa_sec_key_body($rsa, $key_timestamp); # this is for signing. it needs to be an old-style header with a # 2-packet octet count. @@ -551,7 +563,7 @@ sub pem2openpgp { my $key_data = make_packet($packet_types->{pubkey}, $pubkey, {'packet_length'=>2}); # take the last 8 bytes of the fingerprint as the keyid: - my $keyid = substr(fingerprint($rsa, $timestamp), 20 - 8, 8); + my $keyid = substr(fingerprint($rsa, $key_timestamp), 20 - 8, 8); # the v4 signature trailer is: @@ -669,10 +681,10 @@ sub openpgp2ssh { read($instr, $dummy, $packetlen - $readbytes) or die "Could not skip past this packet.\n"; } else { - my $timestamp; - read($instr, $timestamp, 4) or die "could not read key timestamp.\n"; + my $key_timestamp; + read($instr, $key_timestamp, 4) or die "could not read key timestamp.\n"; $readbytes += 4; - $timestamp = unpack('N', $timestamp); + $key_timestamp = unpack('N', $key_timestamp); my $algo; read($instr, $algo, 1) or die "could not read key algorithm.\n"; @@ -687,7 +699,7 @@ sub openpgp2ssh { my $exponent = read_mpi($instr, \$readbytes); my $pubkey = Crypt::OpenSSL::RSA->new_key_from_parameters($modulus, $exponent); - my $foundfpr = fingerprint($pubkey, $timestamp); + my $foundfpr = fingerprint($pubkey, $key_timestamp); my $foundfprstr = Crypt::OpenSSL::Bignum->new_from_bin($foundfpr)->to_hex(); # left-pad with 0's to bring up to full 40-char (160-bit) fingerprint: @@ -778,7 +790,8 @@ for (basename($0)) { print pem2openpgp($rsa, $uid, - { timestamp => $ENV{PEM2OPENPGP_TIMESTAMP}, + { sig_timestamp => $ENV{PEM2OPENPGP_TIMESTAMP}, + key_timestamp => $ENV{PEM2OPENPGP_KEY_TIMESTAMP}, expiration => $ENV{PEM2OPENPGP_EXPIRATION}, usage_flags => $ENV{PEM2OPENPGP_USAGE_FLAGS}, } -- 2.25.1