3 # pem2openpgp: take a PEM-encoded RSA private-key on standard input, a
4 # User ID as the first argument, and generate an OpenPGP certificate
9 # pem2openpgp 'ssh://'$(hostname -f) < /etc/ssh/ssh_host_rsa_key | gpg --import
12 # Jameson Rollins <jrollins@finestructure.net>
13 # Daniel Kahn Gillmor <dkg@fifthhorseman.net>
15 # Started on: 2009-01-07 02:01:19-0500
17 # License: GPL v3 or later (we may need to adjust this given that this
18 # connects to OpenSSL via perl)
22 use Crypt::OpenSSL::RSA;
23 use Crypt::OpenSSL::Bignum;
27 ## make sure all length() and substr() calls use bytes only:
32 # FIXME: fail if there is no given user ID; or should we default to
33 # hostname_long() from Sys::Hostname::Long ?
35 # make an old-style packet out of the given packet type and body.
36 # old-style (see RFC 4880 section 4.2)
41 my $len = length($body);
49 } elsif ($len < 2**16) {
52 } elsif ($len < 2**31) {
53 ## not testing against full 32 bits because i don't want to deal
54 ## with potential overflow.
58 ## what the hell do we do here?
63 return pack('C'.$lencode, 0x80 + ($type * 4) + $lenbytes, $len).
68 # takes a Crypt::OpenSSL::Bignum, returns it formatted as OpenPGP MPI
69 # (RFC 4880 section 3.2)
73 my $val = $num->to_bin();
74 my $mpilen = length($val)*8;
76 # this is a kludgy way to get the number of significant bits in the
78 my $bitsinfirstbyte = length(sprintf("%b", ord($val)));
80 $mpilen -= (8 - $bitsinfirstbyte);
82 return pack('n', $mpilen).$val;
85 # FIXME: genericize this to accept either RSA or DSA keys:
86 sub make_rsa_pub_key_body {
88 my $timestamp = shift;
90 my ($n, $e) = $key->get_key_parameters();
93 pack('CN', 4, $timestamp).
100 # expects an RSA key (public or private) and a timestamp
103 my $timestamp = shift;
105 my $rsabody = make_rsa_pub_key_body($key, $timestamp);
107 return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody);
110 # we're just not dealing with newline business right now. slurp in
116 my $rsa = Crypt::OpenSSL::RSA->new_private_key($buf);
118 $rsa->use_sha1_hash();
119 $rsa->use_no_padding();
121 if (! $rsa->check_key()) {
122 die "key does not check";
125 my $version = pack('C', 4);
126 # strong assertion of identity:
127 my $sigtype = pack('C', 0x13);
129 my $pubkey_algo = pack('C', 1);
131 my $hash_algo = pack('C', 2);
133 # FIXME: i'm worried about generating a bazillion new OpenPGP
134 # certificates from the same key, which could easily happen if you run
135 # this script more than once against the same key. How can we prevent
138 # could an environment variable (if set) override the current time?
139 my $timestamp = time();
141 my $creation_time_packet = pack('CCN', 5, 2, $timestamp);
144 # usage: signing and certification:
146 my $usage_packet = pack('CCC', 2, 27, $flags);
149 # FIXME: HARDCODED: how should we determine how far off to set the
150 # expiration date? default is to expire in 2 days, which is insanely
151 # short (but good for testing).
152 my $expires_in = 86400*2;
153 my $expiration_packet = pack('CCN', 5, 9, $expires_in);
156 # prefer AES-256, AES-192, AES-128, CAST5, 3DES:
157 my $pref_sym_algos = pack('CCCCCCC', 6, 11, 9, 8, 7, 3, 2);
159 # prefer SHA-1, SHA-256, RIPE-MD/160
160 my $pref_hash_algos = pack('CCCCC', 4, 21, 2, 8, 3);
162 # prefer ZLIB, BZip2, ZIP
163 my $pref_zip_algos = pack('CCCCC', 4, 22, 2, 3, 1);
165 # we support the MDC feature:
166 my $features = pack('CCC', 2, 30, 1);
168 # keyserver preference: only owner modify (???):
169 my $keyserver_pref = pack('CCC', 2, 23, 0x80);
171 my $subpackets_to_be_hashed =
172 $creation_time_packet.
181 my $subpacket_octets = pack('n', length($subpackets_to_be_hashed));
183 my $sig_data_to_be_hashed =
189 $subpackets_to_be_hashed;
191 my $pubkey = make_rsa_pub_key_body($rsa, $timestamp);
193 #open(KEYFILE, "</home/wt215/gpg-test/key-data");
194 my $key_data = make_packet(6, $pubkey);
196 # take the last 8 bytes of the fingerprint as the keyid:
197 my $keyid = substr(fingerprint($rsa, $timestamp), 20 - 8, 8);
199 # the v4 signature trailer is:
201 # version number, literal 0xff, and then a 4-byte count of the
202 # signature data itself.
203 my $trailer = pack('CCN', 4, 0xff, length($sig_data_to_be_hashed));
206 pack('CN', 0xb4, length($uid)).
212 $sig_data_to_be_hashed.
215 my $data_hash = Digest::SHA1::sha1_hex($datatosign);
218 my $issuer_packet = pack('CCa8', 9, 16, $keyid);
220 my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign));
223 $sig_data_to_be_hashed.
224 pack('n', length($issuer_packet)).
226 pack('n', hex(substr($data_hash, 0, 4))).
230 make_packet(6, $pubkey).
231 make_packet(13, $uid).
232 make_packet(2, $sig_body);