+my $uid = shift;
+
+# FIXME: fail if there is no given user ID; or should we default to
+# hostname_long() from Sys::Hostname::Long ?
+
+
+
+# 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.
+
+sub modular_multi_inverse {
+ my $a = shift;
+ my $b = shift;
+
+ 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();
+
+ 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";
+ }
+
+ return $lastx;
+}
+
+
+############ OpenPGP formatting functions ############
+