#!/usr/bin/perl -w -T
# pem2openpgp: take a PEM-encoded RSA private-key on standard input, a
-# User ID as the first argument, and generate an OpenPGP certificate
-# from it.
+# User ID as the first argument, and generate an OpenPGP secret key
+# and certificate from it.
+
+# WARNING: the secret key material *will* appear on stdout (albeit in
+# OpenPGP form) -- if you redirect stdout to a file, make sure the
+# permissions on that file are appropriately locked down!
# Usage:
use warnings;
use Crypt::OpenSSL::RSA;
use Crypt::OpenSSL::Bignum;
+use Crypt::OpenSSL::Bignum::CTX;
use Digest::SHA1;
use MIME::Base64;
# FIXME: fail if there is no given user ID; or should we default to
# hostname_long() from Sys::Hostname::Long ?
-# make an old-style packet out of the given packet type and body.
-# old-style (see RFC 4880 section 4.2)
-sub make_packet {
- my $type = shift;
- my $body = shift;
-
- my $len = length($body);
-
- my $lenbytes;
- my $lencode;
-
- if ($len < 2**8) {
- $lenbytes = 0;
- $lencode = 'C';
- } elsif ($len < 2**16) {
- $lenbytes = 1;
- $lencode = 'n';
- } elsif ($len < 2**31) {
- ## not testing against full 32 bits because i don't want to deal
- ## with potential overflow.
- $lenbytes = 2;
- $lencode = 'N';
- } else {
- ## what the hell do we do here?
- $lenbytes = 3;
- $lencode = '';
- }
-
- return pack('C'.$lencode, 0x80 + ($type * 4) + $lenbytes, $len).
- $body;
-}
-
-
-# takes a Crypt::OpenSSL::Bignum, returns it formatted as OpenPGP MPI
-# (RFC 4880 section 3.2)
-sub mpi_pack {
- my $num = shift;
-
- my $val = $num->to_bin();
- my $mpilen = length($val)*8;
-
-# this is a kludgy way to get the number of significant bits in the
-# first byte:
- my $bitsinfirstbyte = length(sprintf("%b", ord($val)));
-
- $mpilen -= (8 - $bitsinfirstbyte);
-
- return pack('n', $mpilen).$val;
-}
-
-# FIXME: genericize this to accept either RSA or DSA keys:
-sub make_rsa_pub_key_body {
- my $key = shift;
- my $timestamp = shift;
-
- my ($n, $e) = $key->get_key_parameters();
-
- return
- pack('CN', 4, $timestamp).
- pack('C', 1). # RSA
- mpi_pack($n).
- mpi_pack($e);
-
-}
-
-# expects an RSA key (public or private) and a timestamp
-sub fingerprint {
- my $key = shift;
- my $timestamp = shift;
-
- my $rsabody = make_rsa_pub_key_body($key, $timestamp);
-
- return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody);
-}
-# FIXME: replace the opaque numbers below with
-# semantically-meaningful references based on these tables.
# see RFC 4880 section 9.1 (ignoring deprecated algorithms for now)
my $asym_algos = { rsa => 1,
issuer => 16,
notation => 20,
preferred_digest => 21,
+ preferred_compression => 22,
keyserver_prefs => 23,
preferred_keyserver => 24,
primary_uid => 25,
embedded_signature => 32,
};
+# bitstring (see RFC 4880 section 5.2.3.24)
+my $features = { mdc => 0x01
+ };
+
+# bitstring (see RFC 4880 5.2.3.17)
+my $keyserver_prefs = { nomodify => 0x80
+ };
+
+###### end lookup tables ######
+
+# FIXME: if we want to be able to interpret openpgp data as well as
+# produce it, we need to produce key/value-swapped lookup tables as well.
+
+
+########### Math/Utility Functions ##############
+
+
+# see the bottom of page 43 of RFC 4880
+sub simple_checksum {
+ my $bytes = shift;
+
+ return unpack("%32W*",$bytes) % 65536;
+}
+
+# calculate the multiplicative inverse of a mod b this is euclid's
+# extended algorithm. For more information see:
+# http://en.wikipedia.org/wiki/Extended_Euclidean_algorithm the
+# arguments here should be Crypt::OpenSSL::Bignum objects. $a should
+# be the larger of the two values, and the two values should be
+# coprime.
+
+sub modular_multi_inverse {
+ my $a = shift;
+ my $b = shift;
+
+ my $ctx = Crypt::OpenSSL::Bignum::CTX->new();
+ my $x = Crypt::OpenSSL::Bignum->zero();
+ my $y = Crypt::OpenSSL::Bignum->one();
+ my $lastx = Crypt::OpenSSL::Bignum->one();
+ my $lasty = Crypt::OpenSSL::Bignum->zero();
+
+ while (! $b->is_zero()) {
+ my ($quotient, $remainder) = $a->div($b, $ctx);
+
+ $a = $b;
+ $b = $remainder;
+
+ my $temp = $x;
+ $x = $lastx->sub($quotient->mul($x, $ctx));
+ $lastx = $temp;
+
+ $temp = $y;
+ $y = $lasty->sub($quotient->mul($y, $ctx));
+ $lasty = $temp;
+ }
+
+ if (!$a->is_one()) {
+ die "did this math wrong.\n";
+ }
+
+ return $lastx;
+}
+
+
+############ OpenPGP formatting functions ############
+
+# make an old-style packet out of the given packet type and body.
+# old-style (see RFC 4880 section 4.2)
+sub make_packet {
+ my $type = shift;
+ my $body = shift;
+
+ my $len = length($body);
+
+ my $lenbytes;
+ my $lencode;
+
+ if ($len < 2**8) {
+ $lenbytes = 0;
+ $lencode = 'C';
+ } elsif ($len < 2**16) {
+ $lenbytes = 1;
+ $lencode = 'n';
+ } elsif ($len < 2**31) {
+ ## not testing against full 32 bits because i don't want to deal
+ ## with potential overflow.
+ $lenbytes = 2;
+ $lencode = 'N';
+ } else {
+ ## what the hell do we do here?
+ $lenbytes = 3;
+ $lencode = '';
+ }
+
+ return pack('C'.$lencode, 0x80 + ($type * 4) + $lenbytes, $len).
+ $body;
+}
+
+
+# takes a Crypt::OpenSSL::Bignum, returns it formatted as OpenPGP MPI
+# (RFC 4880 section 3.2)
+sub mpi_pack {
+ my $num = shift;
+
+ my $val = $num->to_bin();
+ my $mpilen = length($val)*8;
+
+# this is a kludgy way to get the number of significant bits in the
+# first byte:
+ my $bitsinfirstbyte = length(sprintf("%b", ord($val)));
+
+ $mpilen -= (8 - $bitsinfirstbyte);
+
+ return pack('n', $mpilen).$val;
+}
+
+# FIXME: genericize these to accept either RSA or DSA keys:
+sub make_rsa_pub_key_body {
+ my $key = shift;
+ my $timestamp = shift;
+
+ my ($n, $e) = $key->get_key_parameters();
+
+ return
+ pack('CN', 4, $timestamp).
+ pack('C', $asym_algos->{rsa}).
+ mpi_pack($n).
+ mpi_pack($e);
+}
+
+sub make_rsa_sec_key_body {
+ my $key = shift;
+ my $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();
+
+ my $secret_material = mpi_pack($d).
+ mpi_pack($p).
+ mpi_pack($q).
+ mpi_pack(modular_multi_inverse($p, $q));
+
+ # according to Crypt::OpenSSL::RSA, the closest value we can get out
+ # of get_key_parameters is 1/q mod p; but according to sec 5.5.3 of
+ # RFC 4880, we're actually looking for u, the multiplicative inverse
+ # of p, mod q. This is why we're calculating the value directly
+ # with modular_multi_inverse.
+
+ return
+ pack('CN', 4, $timestamp).
+ pack('C', $asym_algos->{rsa}).
+ mpi_pack($n).
+ mpi_pack($e).
+ pack('C', 0). # seckey material is not encrypted -- see RFC 4880 sec 5.5.3
+ $secret_material.
+ pack('n', simple_checksum($secret_material));
+}
+
+# expects an RSA key (public or private) and a timestamp
+sub fingerprint {
+ my $key = shift;
+ my $timestamp = shift;
+
+ my $rsabody = make_rsa_pub_key_body($key, $timestamp);
+
+ return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody);
+}
+
# we're just not dealing with newline business right now. slurp in
# the whole file.
undef $/;
my $version = pack('C', 4);
# strong assertion of identity:
-my $sigtype = pack('C', 0x13);
+my $sigtype = pack('C', $sig_types->{positive_certification});
# RSA
-my $pubkey_algo = pack('C', 1);
+my $pubkey_algo = pack('C', $asym_algos->{rsa});
# SHA1
-my $hash_algo = pack('C', 2);
+my $hash_algo = pack('C', $digests->{sha1});
# FIXME: i'm worried about generating a bazillion new OpenPGP
# certificates from the same key, which could easily happen if you run
-# this script more than once against the same key. How can we prevent
-# this?
+# this script more than once against the same key (because the
+# timestamps will differ). How can we prevent this?
+
+# could an environment variable (if set) override 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 $ENV{PEM2OPENPGP_TIMESTAMP}) {
+ $timestamp = ($ENV{PEM2OPENPGP_TIMESTAMP} + 0);
+} else {
+ $timestamp = time();
+}
-# could an environment variable (if set) override the current time?
-my $timestamp = time();
+my $flags = 0;
+if (! defined $ENV{PEM2OPENPGP_USAGE_FLAGS}) {
+ $flags = $usage_flags->{authenticate};
+} else {
+ my @ff = split(",", $ENV{PEM2OPENPGP_USAGE_FLAGS});
+ foreach my $f (@ff) {
+ if (! defined $usage_flags->{$f}) {
+ die "No such flag $f";
+ }
+ $flags |= $usage_flags->{$f};
+ }
+}
-my $creation_time_packet = pack('CCN', 5, 2, $timestamp);
+my $creation_time_packet = pack('CCN', 5, $subpacket_types->{sig_creation_time}, $timestamp);
# FIXME: HARDCODED: what if someone wants to select a different set of
-# usage flags? For now, we do only authentication.
-my $flags = $usage_flags->{authenticate};
-my $usage_packet = pack('CCC', 2, 27, $flags);
+# usage flags? For now, we do only authentication because that's what
+# monkeysphere needs.
+my $usage_packet = pack('CCC', 2, $subpacket_types->{usage_flags}, $usage_flags->{authenticate});
# FIXME: HARDCODED: how should we determine how far off to set the
# expiration date? default is to expire in 2 days, which is insanely
-# short (but good for testing).
+# short (but good for testing). The user ought to be able to decide
+# this directly, rather than having to do "monkeysphere-server
+# extend-key".
my $expires_in = 86400*2;
-my $expiration_packet = pack('CCN', 5, 9, $expires_in);
+my $expiration_packet = pack('CCN', 5, $subpacket_types->{key_expiration_time}, $expires_in);
# prefer AES-256, AES-192, AES-128, CAST5, 3DES:
-my $pref_sym_algos = pack('CCCCCCC', 6, 11, 9, 8, 7, 3, 2);
+my $pref_sym_algos = pack('CCCCCCC', 6, $subpacket_types->{preferred_cipher},
+ $ciphers->{aes256},
+ $ciphers->{aes192},
+ $ciphers->{aes128},
+ $ciphers->{cast5},
+ $ciphers->{tripledes}
+ );
# prefer SHA-1, SHA-256, RIPE-MD/160
-my $pref_hash_algos = pack('CCCCC', 4, 21, 2, 8, 3);
+my $pref_hash_algos = pack('CCCCC', 4, $subpacket_types->{preferred_digest},
+ $digests->{sha1},
+ $digests->{sha256},
+ $digests->{ripemd160}
+ );
# prefer ZLIB, BZip2, ZIP
-my $pref_zip_algos = pack('CCCCC', 4, 22, 2, 3, 1);
+my $pref_zip_algos = pack('CCCCC', 4, $subpacket_types->{preferred_compression},
+ $zips->{zlib},
+ $zips->{bzip2},
+ $zips->{zip}
+ );
# we support the MDC feature:
-my $features = pack('CCC', 2, 30, 1);
+my $feature_subpacket = pack('CCC', 2, $subpacket_types->{features},
+ $features->{mdc});
# keyserver preference: only owner modify (???):
-my $keyserver_pref = pack('CCC', 2, 23, 0x80);
+my $keyserver_pref = pack('CCC', 2, $subpacket_types->{keyserver_prefs},
+ $keyserver_prefs->{nomodify});
my $subpackets_to_be_hashed =
$creation_time_packet.
$pref_sym_algos.
$pref_hash_algos.
$pref_zip_algos.
- $features.
+ $feature_subpacket.
$keyserver_pref;
my $subpacket_octets = pack('n', length($subpackets_to_be_hashed));
$subpackets_to_be_hashed;
my $pubkey = make_rsa_pub_key_body($rsa, $timestamp);
+my $seckey = make_rsa_sec_key_body($rsa, $timestamp);
-#open(KEYFILE, "</home/wt215/gpg-test/key-data");
-my $key_data = make_packet(6, $pubkey);
+my $key_data = make_packet($packet_types->{pubkey}, $pubkey);
# take the last 8 bytes of the fingerprint as the keyid:
my $keyid = substr(fingerprint($rsa, $timestamp), 20 - 8, 8);
my $data_hash = Digest::SHA1::sha1_hex($datatosign);
-my $issuer_packet = pack('CCa8', 9, 16, $keyid);
+my $issuer_packet = pack('CCa8', 9, $subpacket_types->{issuer}, $keyid);
my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign));
mpi_pack($sig);
print
- make_packet(6, $pubkey).
- make_packet(13, $uid).
- make_packet(2, $sig_body);
+ make_packet($packet_types->{seckey}, $seckey).
+ make_packet($packet_types->{uid}, $uid).
+ make_packet($packet_types->{sig}, $sig_body);
projects / monkeysphere.git / blobdiff