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(************************************************************************)
(* This file is part of SKS. SKS is free software; you can
redistribute it and/or modify it under the terms of the GNU General
Public License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA *)
(***********************************************************************)
(** Conversion to and from ASCII armor *)
open StdLabels
open MoreLabels
open Printf
external crc_of_string : string -> int = "caml_crc_octets"
let base64crc input =
let encoder = Cryptokit.Base64.encode_multiline () in
encoder#put_string input;
encoder#finish;
let base64 = encoder#get_string in
let crc = crc_of_string input in
let encoder = Cryptokit.Base64.encode_compact () in
encoder#put_char (char_of_int ((crc lsr 16) land 0xFF));
encoder#put_char (char_of_int ((crc lsr 8) land 0xFF));
encoder#put_char (char_of_int (crc land 0xFF));
encoder#finish;
let base64 =
if base64.[String.length base64 - 1] <> '\n'
then base64 ^ "\n" else base64 in
base64 ^ "=" ^ encoder#get_string
let pubkey_armor_header = "-----BEGIN PGP PUBLIC KEY BLOCK-----"
let pubkey_armor_tail = "-----END PGP PUBLIC KEY BLOCK-----"
(* pubkey *)
let encode_pubkey key =
let armor_header = pubkey_armor_header
and armor_tail = pubkey_armor_tail
and version = (sprintf "Version: SKS %s" Common.version)
in
let input = Key.to_string key in
armor_header ^ "\n" ^
version ^ "\n\n" ^
base64crc input ^ "\n" ^
armor_tail
let encode_pubkey_string keystr =
let armor_header = pubkey_armor_header
and armor_tail = pubkey_armor_tail
and version = (sprintf "Version: SKS %s" Common.version)
in
let input = keystr in
armor_header ^ "\n" ^
version ^ "\n\n" ^
base64crc input ^ "\n" ^
armor_tail
let decode_crc s =
let decoder = Cryptokit.Base64.decode () in
decoder#put_string s;
decoder#finish;
let b1 = decoder#get_byte in
let b2 = decoder#get_byte in
let b3 = decoder#get_byte in
b1 lsl 16 + b2 lsl 8 + b3
let eol = Str.regexp "[ \t]*\r?\n"
let decode_pubkey text =
let decoder = Cryptokit.Base64.decode () in
let lines = Str.split eol text in
let rec read_adata lines = match lines with
[] -> failwith "Error while decoding ascii-armored key: text terminated before reaching CRC sum"
| line::tl ->
if line.[0] = '='
then ( (* close the decoder and return the CRC string *)
decoder#finish;
let crc = decode_crc (String.sub ~pos:1
~len:(String.length line - 1) line)
and data = decoder#get_string in
(data,crc)
)
else (
decoder#put_string line;
read_adata tl
)
and read_full lines = match lines with
[] -> failwith "Error while decoding ascii-armored key: text terminated before reaching PGP public key header line"
| line::tl ->
if line = pubkey_armor_header then read_block tl
else read_full tl
and read_block lines = match lines with
[] -> failwith "Error while decoding ascii-armored key: text terminated before beginning of ascii block"
| line::tl ->
if line = "" then read_adata tl
else read_block tl
in
let (data,crc) = read_full lines in
let data_crc = crc_of_string data in
assert (data_crc = crc);
Key.of_string_multiple data
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