X-Git-Url: https://codewiz.org/gitweb?a=blobdiff_plain;f=src%2Fkeytrans%2Fpem2openpgp;h=2631da6e99b8bb04bb2a91b5df6be69171f7bea6;hb=6c048ca2dc8ca4ae7708ce8ee5c578ab4ed73c8b;hp=fa92297218db594ae5d9d82e819cddf6086a5d57;hpb=4af5666101d302692f76671c08188141289f13f3;p=monkeysphere.git

diff --git a/src/keytrans/pem2openpgp b/src/keytrans/pem2openpgp
index fa92297..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;
 
@@ -33,6 +38,11 @@ my $uid = shift;
 # 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,
@@ -159,31 +169,105 @@ my $keyserver_prefs = { nomodify => 0x80
 # 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;
+
+
+  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 = '';
   }
 
@@ -209,13 +293,6 @@ sub mpi_pack {
   return pack('n', $mpilen).$val;
 }
 
-# see the bottom of page 43 of RFC 4880
-sub simple_checksum {
-  my $bytes = shift;
-
-  return unpack("%C*",$bytes) % 65536;
-}
-
 # FIXME: genericize these to accept either RSA or DSA keys:
 sub make_rsa_pub_key_body {
   my $key = shift;
@@ -229,23 +306,26 @@ sub make_rsa_pub_key_body {
 	mpi_pack($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, $a, $b, $c) = $key->get_key_parameters();
+  my ($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($c);
+	mpi_pack($c3);
 
-  # FIXME: according to Crypt::OpenSSL::RSA, $c is 1/q mod p; but
-  # according to sec 5.5.3 of RFC 4880, this last argument should
-  # instead be: u, the multiplicative inverse of p, mod q.  i don't
-  # see a simple way to generate this number from the perl module
-  # directly yet.
+  # 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, $timestamp).
@@ -254,7 +334,7 @@ sub make_rsa_sec_key_body {
 	  mpi_pack($e).
 	    pack('C', 0). # seckey material is not encrypted -- see RFC 4880 sec 5.5.3
 	      $secret_material.
-		simple_checksum($secret_material);
+		pack('n', simple_checksum($secret_material));
 }
 
 # expects an RSA key (public or private) and a timestamp
@@ -267,13 +347,16 @@ sub fingerprint {
   return Digest::SHA1::sha1(pack('Cn', 0x99, length($rsabody)).$rsabody);
 }
 
-# we're just not dealing with newline business right now.  slurp in
-# the whole file.
-undef $/;
-my $buf = <STDIN>;
-
 
-my $rsa = Crypt::OpenSSL::RSA->new_private_key($buf);
+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();
 
@@ -295,25 +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:
@@ -370,7 +474,10 @@ my $sig_data_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);
@@ -393,7 +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));
@@ -406,7 +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);