#!/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;
# 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 {
return pack('n', $mpilen).$val;
}
-# see the bottom of page 43 of RFC 4880
-sub simple_checksum {
- my $bytes = shift;
-
- return unpack("%C*",$bytes) % 65536;
-}
-
# FIXME: genericize these to accept either RSA or DSA keys:
sub make_rsa_pub_key_body {
my $key = shift;
mpi_pack($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, $a, $b, $c) = $key->get_key_parameters();
+ my ($n, $e, $d, $p, $q) = $key->get_key_parameters();
my $secret_material = mpi_pack($d).
mpi_pack($p).
mpi_pack($q).
- mpi_pack($c);
+ mpi_pack(modular_multi_inverse($p, $q));
- # FIXME: according to Crypt::OpenSSL::RSA, $c is 1/q mod p; but
- # according to sec 5.5.3 of RFC 4880, this last argument should
- # instead be: u, the multiplicative inverse of p, mod q. i don't
- # see a simple way to generate this number from the perl module
- # directly yet.
+ # 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, $timestamp).
mpi_pack($e).
pack('C', 0). # seckey material is not encrypted -- see RFC 4880 sec 5.5.3
$secret_material.
- simple_checksum($secret_material);
+ pack('n', simple_checksum($secret_material));
}
# expects an RSA key (public or private) and a timestamp
# 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, $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.
+# 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, $subpacket_types->{key_expiration_time}, $expires_in);
mpi_pack($sig);
print
- make_packet($packet_types->{pubkey}, $pubkey).
+ make_packet($packet_types->{seckey}, $seckey).
make_packet($packet_types->{uid}, $uid).
make_packet($packet_types->{sig}, $sig_body);
projects / monkeysphere.git / blobdiff