pem2openpgp: clean up comments, treat fingerprint as raw data instead of ascii

[monkeysphere.git] / src / keytrans / pem2openpgp

diff --git a/src/keytrans/pem2openpgp b/src/keytrans/pem2openpgp
index 1575671eab27be5b2bf6075679dbe5e39c430ba4..7522c8ff2abc94b296256a7a958eb0ad31c0f770 100755 (executable)
--- a/src/keytrans/pem2openpgp
+++ b/src/keytrans/pem2openpgp
@@ -4,6 +4,10 @@
 # User ID as the first argument, and generate an OpenPGP certificate
 # from it.
 
+# Usage:
+
+# pem2openpgp 'ssh://'$(hostname -f) < /etc/ssh/ssh_host_rsa_key | gpg --import
+
 # Authors:
 #  Jameson Rollins <jrollins@finestructure.net>
 #  Daniel Kahn Gillmor <dkg@fifthhorseman.net>
@@ -23,13 +27,17 @@ use MIME::Base64;
 ## make sure all length() and substr() calls use bytes only:
 use bytes;
 
+my $uid = shift;
+
+# 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;
 
-# FIXME: yet another length():
   my $len = length($body);
 
   my $lenbytes;
@@ -62,19 +70,20 @@ sub make_packet {
 sub mpi_pack {
   my $num = shift;
 
-  my $hex = $num->to_hex();
-
-  my $mpilen = length($hex)*4;
+  my $val = $num->to_bin();
+  my $mpilen = length($val)*8;
 
-# this is a kludgy way to get the number of bits in the first byte:
-  my $bitsinfirstbyte = length(sprintf("%b", hex(substr $hex, 0, 2)));
+# 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', $mpilen).$num->to_bin();
+  return pack('n', $mpilen).$val;
 }
+
 # FIXME: genericize this to accept either RSA or DSA keys:
-sub make_rsa_key_body {
+sub make_rsa_pub_key_body {
   my $key = shift;
   my $timestamp = shift;
 
@@ -93,12 +102,13 @@ sub fingerprint {
   my $key = shift;
   my $timestamp = shift;
 
-  my $rsabody = make_rsa_key_body($key, $timestamp);
+  my $rsabody = make_rsa_pub_key_body($key, $timestamp);
 
-  return Digest::SHA1::sha1_hex(pack('Cn', 0x99, length($rsabody)).$rsabody);
+  return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody);
 }
 
-my $holdTerminator = $/;
+# we're just not dealing with newline business right now.  slurp in
+# the whole file.
 undef $/;
 my $buf = <STDIN>;
 
@@ -112,10 +122,6 @@ if (! $rsa->check_key()) {
   die "key does not check";
 }
 
-my $uid = 'fake key (do not use) <test@example.org>';
-
-
-
 my $version = pack('C', 4);
 # strong assertion of identity:
 my $sigtype = pack('C', 0x13);
@@ -124,9 +130,13 @@ my $pubkey_algo = pack('C', 1);
 # SHA1
 my $hash_algo = pack('C', 2);
 
+# 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?
 
-
-my $timestamp = 1231003584;
+# could an environment variable (if set) override the current time?
+my $timestamp = time();
 
 my $creation_time_packet = pack('CCN', 5, 2, $timestamp);
 
@@ -136,7 +146,9 @@ my $flags = 0x03;
 my $usage_packet = pack('CCC', 2, 27, $flags);
 
 
-# expire in 2 days:
+# 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).
 my $expires_in = 86400*2;
 my $expiration_packet = pack('CCN', 5, 9, $expires_in);
 
@@ -166,7 +178,6 @@ my $subpackets_to_be_hashed =
   $features.
   $keyserver_pref;
 
-#FIXME: what's the right way to get length()?
 my $subpacket_octets = pack('n', length($subpackets_to_be_hashed));
 
 my $sig_data_to_be_hashed =
@@ -177,13 +188,13 @@ my $sig_data_to_be_hashed =
   $subpacket_octets.
   $subpackets_to_be_hashed;
 
-my $pubkey = make_rsa_key_body($rsa, $timestamp);
+my $pubkey = make_rsa_pub_key_body($rsa, $timestamp);
 
 #open(KEYFILE, "</home/wt215/gpg-test/key-data");
 my $key_data = make_packet(6, $pubkey);
 
-# take the last 16 characters of the fingerprint as the keyid:
-my $keyid = substr(fingerprint($rsa, $timestamp), 40 - 16, 16);
+# 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:
 
@@ -191,8 +202,6 @@ my $keyid = substr(fingerprint($rsa, $timestamp), 40 - 16, 16);
 # signature data itself.
 my $trailer = pack('CCN', 4, 0xff, length($sig_data_to_be_hashed));
 
-# FIXME: length() is probably not right here either in the event that
-# the uid uses unicode.
 my $uid_data =
   pack('CN', 0xb4, length($uid)).
   $uid;
@@ -206,20 +215,20 @@ my $datatosign =
 my $data_hash = Digest::SHA1::sha1_hex($datatosign);
 
 
-my $issuer_packet = pack('CCH16', 9, 16, $keyid);
+my $issuer_packet = pack('CCa8', 9, 16, $keyid);
 
 my $sig = Crypt::OpenSSL::Bignum->new_from_bin($rsa->sign($datatosign));
 
 my $sig_body =
   $sig_data_to_be_hashed.
-# FIXME: another dubious length() call.
   pack('n', length($issuer_packet)).
   $issuer_packet.
   pack('n', hex(substr($data_hash, 0, 4))).
   mpi_pack($sig);
 
-print make_packet(6, $pubkey);
-print make_packet(13, $uid);
-print make_packet(2, $sig_body);
+print
+  make_packet(6, $pubkey).
+  make_packet(13, $uid).
+  make_packet(2, $sig_body);
+
 
-$/ = $holdTerminator;