X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;ds=sidebyside;f=src%2Fkeytrans%2Fpem2openpgp;h=2631da6e99b8bb04bb2a91b5df6be69171f7bea6;hb=6e371ad70b96003d50c769a2d2f6fd82c15d4bb5;hp=59f9bb0db7f5f5bb14cff55aa56b05345b571383;hpb=ef9469ee700eacfb9da0b2d897b82fbe1287e864;p=monkeysphere.git

diff --git a/src/keytrans/pem2openpgp b/src/keytrans/pem2openpgp
index 59f9bb0..2631da6 100755
--- a/src/keytrans/pem2openpgp
+++ b/src/keytrans/pem2openpgp
@@ -1,8 +1,16 @@
 #!/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>
@@ -17,78 +25,442 @@ use strict;
 use warnings;
 use Crypt::OpenSSL::RSA;
 use Crypt::OpenSSL::Bignum;
+use Crypt::OpenSSL::Bignum::CTX;
 use Digest::SHA1;
 use MIME::Base64;
 
-my $holdTerminator = $/;
-undef $/;
-my $buf = <STDIN>;
+## 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 ?
+
+
+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.
 
-my $rsa = Crypt::OpenSSL::RSA->new_private_key($buf);
+sub modular_multi_inverse {
+  my $a = shift;
+  my $b = shift;
 
-$rsa->use_sha1_hash();
-$rsa->use_no_padding();
 
-if (! $rsa->check_key()) {
-  die "key does not check";
+  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 $lencode;
+
+  if ($pseudolen < 2**8) {
+    $lenbytes = $old_format_packet_lengths->{one};
+    $lencode = 'C';
+  } elsif ($pseudolen < 2**16) {
+    $lenbytes = $old_format_packet_lengths->{two};
+    $lencode = 'n';
+  } elsif ($pseudolen < 2**31) {
+    ## not testing against full 32 bits because i don't want to deal
+    ## with potential overflow.
+    $lenbytes = $old_format_packet_lengths->{four};
+    $lencode = 'N';
+  } else {
+    ## what the hell do we do here?
+    $lenbytes = $old_format_packet_lengths->{indeterminate};
+    $lencode = '';
+  }
+
+  return pack('C'.$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 $c3 = modular_multi_inverse($p, $q);
+
+  my $secret_material = mpi_pack($d).
+    mpi_pack($p).
+      mpi_pack($q).
+	mpi_pack($c3);
+
+  # 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));
 }
 
-my $uid = 'fake key (do not use) <test@example.org>';
+# 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);
+}
+
+
+my $rsa;
+if (defined $ENV{PEM2OPENPGP_NEWKEY}) {
+  $rsa = Crypt::OpenSSL::RSA->generate_key($ENV{PEM2OPENPGP_NEWKEY});
+} else {
+  # we're just not dealing with newline business right now.  slurp in
+  # the whole file.
+  undef $/;
+  $rsa = Crypt::OpenSSL::RSA->new_private_key(<STDIN>);
+}
+
+$rsa->use_sha1_hash();
+
+# see page 22 of RFC 4880 for why i think this is the right padding
+# choice to use:
+$rsa->use_pkcs1_padding();
+
+if (! $rsa->check_key()) {
+  die "key does not check";
+}
 
 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 (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 $ENV{PEM2OPENPGP_TIMESTAMP}) {
+  $timestamp = ($ENV{PEM2OPENPGP_TIMESTAMP} + 0);
+} else {
+  $timestamp = time();
+}
 
-my $timestamp = 1231003584;
+my $creation_time_packet = pack('CCN', 5, $subpacket_types->{sig_creation_time}, $timestamp);
 
-my $creation_time_packet = pack('CCN', 5, 2, $timestamp);
 
+my $flags = 0;
+if (! defined $ENV{PEM2OPENPGP_USAGE_FLAGS}) {
+  $flags = $usage_flags->{certify};
+} 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};
+  }
+}
 
-# usage: signing and certification:
-my $flags = 0x03;
-my $usage_packet = pack('CCC', 2, 27, $flags);
+my $usage_packet = pack('CCC', 2, $subpacket_types->{usage_flags}, $flags);
 
 
-# expire in 2 days:
-my $expires_in = 86400*2;
-my $expiration_packet = pack('CCN', 5, 9, $expires_in);
+# 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 $ENV{PEM2OPENPGP_EXPIRATION}) {
+  my $expires_in = $ENV{PEM2OPENPGP_EXPIRATION} + 0;
+  $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 = 
+my $subpackets_to_be_hashed =
   $creation_time_packet.
   $usage_packet.
   $expiration_packet.
   $pref_sym_algos.
   $pref_hash_algos.
   $pref_zip_algos.
-  $features.
+  $feature_subpacket.
   $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 =
@@ -99,16 +471,16 @@ my $sig_data_to_be_hashed =
   $subpacket_octets.
   $subpackets_to_be_hashed;
 
+my $pubkey = make_rsa_pub_key_body($rsa, $timestamp);
+my $seckey = make_rsa_sec_key_body($rsa, $timestamp);
 
-my ($n, $e, $d, $p, $q) = $rsa->get_key_parameters();
+# 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});
 
-open(KEYFILE, "</home/wt215/gpg-test/key-data");
-my $key_data = <KEYFILE>;
-
-# FIXME: $keyid should be generated from the public key instead of
-# hardcoded:
-my $keyid = '5616d7cb02e69446';
+# 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:
 
@@ -116,8 +488,6 @@ my $keyid = '5616d7cb02e69446';
 # 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;
@@ -130,51 +500,20 @@ my $datatosign =
 
 my $data_hash = Digest::SHA1::sha1_hex($datatosign);
 
+my $issuer_packet = pack('CCa8', 9, $subpacket_types->{issuer}, $keyid);
 
-my $issuer_packet = pack('CCH16', 9, 16, $keyid);
-
-my $sig = $rsa->sign($datatosign);
-
-my $bigsig = Crypt::OpenSSL::Bignum->new_from_bin($sig);
-
-
-my $hex = $bigsig->to_hex();
-
-my $mpilen = length($hex)*4;
-
-# this is a kludgy way to get the number of bits in the first byte:
-my $bitsinfirstbyte = length(sprintf("%b", hex(substr $hex, 0, 2)));
-
-$mpilen -= (8 - $bitsinfirstbyte);
-
-# emit two octets representing $mpilen, followed by the signature itself:
-
+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))).
-  pack("n" , $mpilen).
-  $sig;
+  mpi_pack($sig);
 
-# FIXME: yet another length():
-my $len = length($sig_body);
-
-my $header;
-
-if ($len < 2**8) {
-  $header = pack('CC', 0x88, $len);
-} elsif ($len < 2**16) {
-  $header = pack('Cn', 0x89, $len);
-} elsif ($len < 2**31) {
-  $header = pack('CN', 0x8a, $len);
-} else {
-  # what the hell do we do here?
-  $header = pack('C', 0x8b);
-}
+print
+  make_packet($packet_types->{seckey}, $seckey).
+  make_packet($packet_types->{uid}, $uid).
+  make_packet($packet_types->{sig}, $sig_body);
 
-print $header.$sig_body;
 
-$/ = $holdTerminator;