X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=src%2Fkeytrans%2Fpem2openpgp;h=2631da6e99b8bb04bb2a91b5df6be69171f7bea6;hb=39996655a57ca3167e733d0a0457941ae4060270;hp=637eba2a225fecbc399a64e3ad6433461b63a36c;hpb=3f5960cf4ba2f938c677c27e3296e6feae2f56aa;p=monkeysphere.git

diff --git a/src/keytrans/pem2openpgp b/src/keytrans/pem2openpgp
index 637eba2..2631da6 100755
--- a/src/keytrans/pem2openpgp
+++ b/src/keytrans/pem2openpgp
@@ -1,8 +1,12 @@
 #!/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:
 
@@ -21,6 +25,7 @@ use strict;
 use warnings;
 use Crypt::OpenSSL::RSA;
 use Crypt::OpenSSL::Bignum;
+use Crypt::OpenSSL::Bignum::CTX;
 use Digest::SHA1;
 use MIME::Base64;
 
@@ -32,83 +37,12 @@ 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;
-
-  my $len = length($body);
-
-  my $lenbytes;
-  my $lencode;
-
-  if ($len < 2**8) {
-    $lenbytes = 0;
-    $lencode = 'C';
-  } elsif ($len < 2**16) {
-    $lenbytes = 1;
-    $lencode = 'n';
-  } elsif ($len < 2**31) {
-    ## not testing against full 32 bits because i don't want to deal
-    ## with potential overflow.
-    $lenbytes = 2;
-    $lencode = 'N';
-  } else {
-    ## what the hell do we do here?
-    $lenbytes = 3;
-    $lencode = '';
-  }
-
-  return pack('C'.$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 this 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, $timestamp).
-      pack('C', 1). # RSA
-	mpi_pack($n).
-	  mpi_pack($e);
-
-}
-
-# 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);
-}
-
-# FIXME: replace the opaque numbers below with
-# semantically-meaningful references based on these tables.
+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,
@@ -229,13 +163,200 @@ my $features = { mdc => 0x01
 my $keyserver_prefs = { nomodify => 0x80
 		      };
 
-# we're just not dealing with newline business right now.  slurp in
-# the whole file.
-undef $/;
-my $buf = <STDIN>;
+###### 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 ##############
 
 
-my $rsa = Crypt::OpenSSL::RSA->new_private_key($buf);
+# 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 $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));
+}
+
+# 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();
 
@@ -257,25 +378,46 @@ 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.  How can we prevent
-# this?
-
-# could an environment variable (if set) override the current time?
-my $timestamp = time();
+# 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 $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.
-my $usage_packet = pack('CCC', 2, $subpacket_types->{usage_flags}, $usage_flags->{authenticate});
+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};
+  }
+}
+
+my $usage_packet = pack('CCC', 2, $subpacket_types->{usage_flags}, $flags);
 
 
-# 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, $subpacket_types->{key_expiration_time}, $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:
@@ -330,8 +472,12 @@ my $sig_data_to_be_hashed =
   $subpackets_to_be_hashed;
 
 my $pubkey = make_rsa_pub_key_body($rsa, $timestamp);
+my $seckey = make_rsa_sec_key_body($rsa, $timestamp);
 
-my $key_data = make_packet($packet_types->{pubkey}, $pubkey);
+# 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);
@@ -354,7 +500,6 @@ my $datatosign =
 
 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));
@@ -367,7 +512,7 @@ my $sig_body =
   mpi_pack($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);