#!/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:
+
+# pem2openpgp 'ssh://'$(hostname -f) < /etc/ssh/ssh_host_rsa_key | gpg --import
# Authors:
# Jameson Rollins <jrollins@finestructure.net>
use warnings;
use Crypt::OpenSSL::RSA;
use Crypt::OpenSSL::Bignum;
+use Crypt::OpenSSL::Bignum::CTX;
use Digest::SHA1;
use MIME::Base64;
## make sure all length() and substr() calls use bytes only:
use bytes;
-my $uid = shift;
+my $old_format_packet_lengths = { one => 0,
+ two => 1,
+ four => 2,
+ indeterminate => 3,
+};
+
+# see RFC 4880 section 9.1 (ignoring deprecated algorithms for now)
+my $asym_algos = { rsa => 1,
+ elgamal => 16,
+ dsa => 17,
+ };
+
+# see RFC 4880 section 9.2
+my $ciphers = { plaintext => 0,
+ idea => 1,
+ tripledes => 2,
+ cast5 => 3,
+ blowfish => 4,
+ aes128 => 7,
+ aes192 => 8,
+ aes256 => 9,
+ twofish => 10,
+ };
+
+# see RFC 4880 section 9.3
+my $zips = { uncompressed => 0,
+ zip => 1,
+ zlib => 2,
+ bzip2 => 3,
+ };
+
+# see RFC 4880 section 9.4
+my $digests = { md5 => 1,
+ sha1 => 2,
+ ripemd160 => 3,
+ sha256 => 8,
+ sha384 => 9,
+ sha512 => 10,
+ sha224 => 11,
+ };
+
+# see RFC 4880 section 5.2.3.21
+my $usage_flags = { certify => 0x01,
+ sign => 0x02,
+ encrypt_comms => 0x04,
+ encrypt_storage => 0x08,
+ encrypt => 0x0c, ## both comms and storage
+ split => 0x10, # the private key is split via secret sharing
+ authenticate => 0x20,
+ shared => 0x80, # more than one person holds the entire private key
+ };
+
+# see RFC 4880 section 4.3
+my $packet_types = { pubkey_enc_session => 1,
+ sig => 2,
+ symkey_enc_session => 3,
+ onepass_sig => 4,
+ seckey => 5,
+ pubkey => 6,
+ sec_subkey => 7,
+ compressed_data => 8,
+ symenc_data => 9,
+ marker => 10,
+ literal => 11,
+ trust => 12,
+ uid => 13,
+ pub_subkey => 14,
+ uat => 17,
+ symenc_w_integrity => 18,
+ mdc => 19,
+ };
+
+# see RFC 4880 section 5.2.1
+my $sig_types = { binary_doc => 0x00,
+ text_doc => 0x01,
+ standalone => 0x02,
+ generic_certification => 0x10,
+ persona_certification => 0x11,
+ casual_certification => 0x12,
+ positive_certification => 0x13,
+ subkey_binding => 0x18,
+ primary_key_binding => 0x19,
+ key_signature => 0x1f,
+ key_revocation => 0x20,
+ subkey_revocation => 0x28,
+ certification_revocation => 0x30,
+ timestamp => 0x40,
+ thirdparty => 0x50,
+ };
+
+
+# see RFC 4880 section 5.2.3.1
+my $subpacket_types = { sig_creation_time => 2,
+ sig_expiration_time => 3,
+ exportable => 4,
+ trust_sig => 5,
+ regex => 6,
+ revocable => 7,
+ key_expiration_time => 9,
+ preferred_cipher => 11,
+ revocation_key => 12,
+ issuer => 16,
+ notation => 20,
+ preferred_digest => 21,
+ preferred_compression => 22,
+ keyserver_prefs => 23,
+ preferred_keyserver => 24,
+ primary_uid => 25,
+ policy_uri => 26,
+ usage_flags => 27,
+ signers_uid => 28,
+ revocation_reason => 29,
+ features => 30,
+ signature_target => 31,
+ 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;
+
-# FIXME: fail if there is no given user ID.
+ my $origdivisor = $b->copy();
+
+ 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();
+
+ my $finalquotient;
+ my $finalremainder;
+
+ 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";
+ }
+
+ # let's make sure that we return a positive value because RFC 4880,
+ # section 3.2 only allows unsigned values:
+
+ ($finalquotient, $finalremainder) = $lastx->add($origdivisor)->div($origdivisor, $ctx);
+
+ return $finalremainder;
+}
+
+
+############ 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 $options = shift;
my $len = length($body);
+ my $pseudolen = $len;
+
+ # if the caller wants to use at least N octets of packet length,
+ # pretend that we're using that many.
+ if (defined $options && defined $options->{'packet_length'}) {
+ $pseudolen = 2**($options->{'packet_length'} * 8) - 1;
+ }
+ if ($pseudolen < $len) {
+ $pseudolen = $len;
+ }
my $lenbytes;
my $lencode;
- if ($len < 2**8) {
- $lenbytes = 0;
+ if ($pseudolen < 2**8) {
+ $lenbytes = $old_format_packet_lengths->{one};
$lencode = 'C';
- } elsif ($len < 2**16) {
- $lenbytes = 1;
+ } elsif ($pseudolen < 2**16) {
+ $lenbytes = $old_format_packet_lengths->{two};
$lencode = 'n';
- } elsif ($len < 2**31) {
+ } elsif ($pseudolen < 2**31) {
## not testing against full 32 bits because i don't want to deal
## with potential overflow.
- $lenbytes = 2;
+ $lenbytes = $old_format_packet_lengths->{four};
$lencode = 'N';
} else {
## what the hell do we do here?
- $lenbytes = 3;
+ $lenbytes = $old_format_packet_lengths->{indeterminate};
$lencode = '';
}
return pack('n', $mpilen).$val;
}
-# FIXME: genericize this to accept either RSA or DSA keys:
-sub make_rsa_key_body {
+# FIXME: genericize these to accept either RSA or DSA keys:
+sub make_rsa_pub_key_body {
my $key = shift;
my $timestamp = shift;
return
pack('CN', 4, $timestamp).
- pack('C', 1). # RSA
+ pack('C', $asym_algos->{rsa}).
mpi_pack($n).
mpi_pack($e);
-
}
-# expects an RSA key (public or private) and a timestamp
-sub fingerprint {
+sub make_rsa_sec_key_body {
my $key = shift;
my $timestamp = shift;
- my $rsabody = make_rsa_key_body($key, $timestamp);
+ # we're not using $a and $b, but we need them to get to $c.
+ my ($n, $e, $d, $p, $q) = $key->get_key_parameters();
- return Digest::SHA1::sha1_hex(pack('Cn', 0x99, length($rsabody)).$rsabody);
-}
-
-my $holdTerminator = $/;
-undef $/;
-my $buf = <STDIN>;
+ my $c3 = modular_multi_inverse($p, $q);
+ my $secret_material = mpi_pack($d).
+ mpi_pack($p).
+ mpi_pack($q).
+ mpi_pack($c3);
-my $rsa = Crypt::OpenSSL::RSA->new_private_key($buf);
+ # 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.
-$rsa->use_sha1_hash();
-$rsa->use_no_padding();
-
-if (! $rsa->check_key()) {
- die "key does not check";
+ 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));
}
-my $version = pack('C', 4);
-# strong assertion of identity:
-my $sigtype = pack('C', 0x13);
-# RSA
-my $pubkey_algo = pack('C', 1);
-# SHA1
-my $hash_algo = pack('C', 2);
-
-
-
-my $timestamp = 1231003584;
-
-my $creation_time_packet = pack('CCN', 5, 2, $timestamp);
-
-
-# usage: signing and certification:
-my $flags = 0x03;
-my $usage_packet = pack('CCC', 2, 27, $flags);
-
+# expects an RSA key (public or private) and a timestamp
+sub fingerprint {
+ my $key = shift;
+ my $timestamp = shift;
-# expire in 2 days:
-my $expires_in = 86400*2;
-my $expiration_packet = pack('CCN', 5, 9, $expires_in);
+ my $rsabody = make_rsa_pub_key_body($key, $timestamp);
+ return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody);
+}
-# prefer AES-256, AES-192, AES-128, CAST5, 3DES:
-my $pref_sym_algos = pack('CCCCCCC', 6, 11, 9, 8, 7, 3, 2);
-# prefer SHA-1, SHA-256, RIPE-MD/160
-my $pref_hash_algos = pack('CCCCC', 4, 21, 2, 8, 3);
+# FIXME: handle DSA keys as well!
+sub pem2openpgp {
+ my $rsa = shift;
+ my $uid = shift;
+ my $args = shift;
-# prefer ZLIB, BZip2, ZIP
-my $pref_zip_algos = pack('CCCCC', 4, 22, 2, 3, 1);
+ $rsa->use_sha1_hash();
-# we support the MDC feature:
-my $features = pack('CCC', 2, 30, 1);
+ # see page 22 of RFC 4880 for why i think this is the right padding
+ # choice to use:
+ $rsa->use_pkcs1_padding();
-# keyserver preference: only owner modify (???):
-my $keyserver_pref = pack('CCC', 2, 23, 0x80);
+ if (! $rsa->check_key()) {
+ die "key does not check";
+ }
-my $subpackets_to_be_hashed =
- $creation_time_packet.
- $usage_packet.
- $expiration_packet.
- $pref_sym_algos.
- $pref_hash_algos.
- $pref_zip_algos.
- $features.
- $keyserver_pref;
+ my $version = pack('C', 4);
+ # strong assertion of identity:
+ my $sigtype = pack('C', $sig_types->{positive_certification});
+ # RSA
+ my $pubkey_algo = pack('C', $asym_algos->{rsa});
+ # SHA1
+ 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 (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
+ # instead of stdin, should we use the creation time on the file?
+ my $timestamp = 0;
+ if (defined $args->{timestamp}) {
+ $timestamp = ($args->{timestamp} + 0);
+ } else {
+ $timestamp = time();
+ }
-my $subpacket_octets = pack('n', length($subpackets_to_be_hashed));
+ my $creation_time_packet = pack('CCN', 5, $subpacket_types->{sig_creation_time}, $timestamp);
-my $sig_data_to_be_hashed =
- $version.
- $sigtype.
- $pubkey_algo.
- $hash_algo.
- $subpacket_octets.
- $subpackets_to_be_hashed;
-my $pubkey = make_rsa_key_body($rsa, $timestamp);
+ my $flags = 0;
+ if (! defined $args->{usage_flags}) {
+ $flags = $usage_flags->{certify};
+ } else {
+ my @ff = split(",", $args->{usage_flags});
+ foreach my $f (@ff) {
+ if (! defined $usage_flags->{$f}) {
+ die "No such flag $f";
+ }
+ $flags |= $usage_flags->{$f};
+ }
+ }
-#open(KEYFILE, "</home/wt215/gpg-test/key-data");
-my $key_data = make_packet(6, $pubkey);
+ my $usage_packet = pack('CCC', 2, $subpacket_types->{usage_flags}, $flags);
-# take the last 16 characters of the fingerprint as the keyid:
-my $keyid = substr(fingerprint($rsa, $timestamp), 40 - 16, 16);
-# the v4 signature trailer is:
+ # how should we determine how far off to set the expiration date?
+ # default is no expiration. Specify the timestamp in seconds from the
+ # key creation.
+ my $expiration_packet = '';
+ if (defined $args->{expiration}) {
+ my $expires_in = $args->{expiration} + 0;
+ $expiration_packet = pack('CCN', 5, $subpacket_types->{key_expiration_time}, $expires_in);
+ }
-# version number, literal 0xff, and then a 4-byte count of the
-# signature data itself.
-my $trailer = pack('CCN', 4, 0xff, length($sig_data_to_be_hashed));
-my $uid_data =
- pack('CN', 0xb4, length($uid)).
- $uid;
+ # prefer AES-256, AES-192, AES-128, CAST5, 3DES:
+ 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, $subpacket_types->{preferred_digest},
+ $digests->{sha1},
+ $digests->{sha256},
+ $digests->{ripemd160}
+ );
+
+ # prefer ZLIB, BZip2, ZIP
+ my $pref_zip_algos = pack('CCCCC', 4, $subpacket_types->{preferred_compression},
+ $zips->{zlib},
+ $zips->{bzip2},
+ $zips->{zip}
+ );
+
+ # we support the MDC feature:
+ my $feature_subpacket = pack('CCC', 2, $subpacket_types->{features},
+ $features->{mdc});
+
+ # keyserver preference: only owner modify (???):
+ my $keyserver_pref = pack('CCC', 2, $subpacket_types->{keyserver_prefs},
+ $keyserver_prefs->{nomodify});
+
+ my $subpackets_to_be_hashed =
+ $creation_time_packet.
+ $usage_packet.
+ $expiration_packet.
+ $pref_sym_algos.
+ $pref_hash_algos.
+ $pref_zip_algos.
+ $feature_subpacket.
+ $keyserver_pref;
+
+ my $subpacket_octets = pack('n', length($subpackets_to_be_hashed));
+
+ my $sig_data_to_be_hashed =
+ $version.
+ $sigtype.
+ $pubkey_algo.
+ $hash_algo.
+ $subpacket_octets.
+ $subpackets_to_be_hashed;
+
+ my $pubkey = make_rsa_pub_key_body($rsa, $timestamp);
+ my $seckey = make_rsa_sec_key_body($rsa, $timestamp);
+
+ # this is for signing. it needs to be an old-style header with a
+ # 2-packet octet count.
+
+ 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);
+
+ # the v4 signature trailer is:
+
+ # version number, literal 0xff, and then a 4-byte count of the
+ # signature data itself.
+ my $trailer = pack('CCN', 4, 0xff, length($sig_data_to_be_hashed));
+
+ my $uid_data =
+ pack('CN', 0xb4, length($uid)).
+ $uid;
+
+ my $datatosign =
+ $key_data.
+ $uid_data.
+ $sig_data_to_be_hashed.
+ $trailer;
+
+ my $data_hash = Digest::SHA1::sha1_hex($datatosign);
+
+ my $issuer_packet = pack('CCa8', 9, $subpacket_types->{issuer}, $keyid);
+
+ my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign));
+
+ my $sig_body =
+ $sig_data_to_be_hashed.
+ pack('n', length($issuer_packet)).
+ $issuer_packet.
+ pack('n', hex(substr($data_hash, 0, 4))).
+ mpi_pack($sig);
-my $datatosign =
- $key_data.
- $uid_data.
- $sig_data_to_be_hashed.
- $trailer;
+ return
+ make_packet($packet_types->{seckey}, $seckey).
+ make_packet($packet_types->{uid}, $uid).
+ make_packet($packet_types->{sig}, $sig_body);
+}
-my $data_hash = Digest::SHA1::sha1_hex($datatosign);
+my $rsa;
+if (defined $ENV{PEM2OPENPGP_NEWKEY}) {
+ $rsa = Crypt::OpenSSL::RSA->generate_key($ENV{PEM2OPENPGP_NEWKEY});
+} else {
+ # slurp in the entire stdin:
+ undef $/;
+ my $stdin = <STDIN>;
-my $issuer_packet = pack('CCH16', 9, 16, $keyid);
+ $rsa = Crypt::OpenSSL::RSA->new_private_key($stdin);
+}
-my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign));
+my $uid = shift;
-my $sig_body =
- $sig_data_to_be_hashed.
- pack('n', length($issuer_packet)).
- $issuer_packet.
- pack('n', hex(substr($data_hash, 0, 4))).
- mpi_pack($sig);
+# FIXME: fail if there is no given user ID; or should we default to
+# hostname_long() from Sys::Hostname::Long ?
-print make_packet(6, $pubkey);
-print make_packet(13, $uid);
-print make_packet(2, $sig_body);
+print pem2openpgp($rsa,
+ $uid,
+ { timestamp => $ENV{PEM2OPENPGP_TIMESTAMP},
+ expiration => $ENV{PEM2OPENPGP_EXPIRATION},
+ usage_flags => $ENV{PEM2OPENPGP_USAGE_FLAGS},
+ }
+ );
-$/ = $holdTerminator;
projects / monkeysphere.git / blobdiff