pgpmicalg.c File Reference

Identify the hash algorithm from a PGP signature. More...

#include "config.h"
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include "mutt/lib.h"
#include "core/lib.h"
#include "pgpmicalg.h"
#include "handler.h"
#include "pgppacket.h"

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Data Structures
struct	HashAlgorithm
	PGP Hashing algorithm. More...

Functions
static const char *	pgp_hash_to_micalg (short id)
	Lookup a hash name, given its id.
static void	pgp_dearmor (FILE *fp_in, FILE *fp_out)
	Unwrap an armoured PGP block.
static short	pgp_mic_from_packet (unsigned char *p, size_t len)
	Get the hash algorithm from a PGP packet.
static short	pgp_find_hash (const char *fname)
	Find the hash algorithm of a file.
const char *	pgp_micalg (const char *fname)
	Find the hash algorithm of a file.

Variables
static const struct HashAlgorithm	HashAlgorithms []
	PGP Hashing algorithms.

Detailed Description

Identify the hash algorithm from a PGP signature.

Authors

• Richard Russon
• Pietro Cerutti

Copyright

This program 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, see http://www.gnu.org/licenses/.

Definition in file pgpmicalg.c.

Function Documentation

pgp_hash_to_micalg()

static const char * pgp_hash_to_micalg ( short id )

static

Lookup a hash name, given its id.

Parameters

id

ID

Return values

ptr	Name of hash algorithm

Definition at line 64 of file pgpmicalg.c.

{
  for (int i = 0; HashAlgorithms[i].id >= 0; i++)
    if (HashAlgorithms[i].id == id)
      return HashAlgorithms[i].name;
  return "x-unknown";
}

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pgp_dearmor()

static void pgp_dearmor ( FILE * fp_in, FILE * fp_out )

static

Unwrap an armoured PGP block.

Parameters

fp_in	File to read from
fp_out	File to write to

Definition at line 77 of file pgpmicalg.c.

{
  char line[8192] = { 0 };
  char *r = NULL;
 
  struct State state = { 0 };
  state.fp_in = fp_in;
  state.fp_out = fp_out;
 
  /* find the beginning of ASCII armor */
 
  while ((r = fgets(line, sizeof(line), fp_in)))
  {
    if (mutt_strn_equal(line, "-----BEGIN", 10))
      break;
  }
  if (!r)
  {
    mutt_debug(LL_DEBUG1, "Can't find begin of ASCII armor\n");
    return;
  }
 
  /* skip the armor header */
 
  while ((r = fgets(line, sizeof(line), fp_in)))
  {
    SKIPWS(r);
    if (*r == '\0')
      break;
  }
  if (!r)
  {
    mutt_debug(LL_DEBUG1, "Armor header doesn't end\n");
    return;
  }
 
  /* actual data starts here */
  LOFF_T start = ftello(fp_in);
  if (start < 0)
    return;
 
  /* find the checksum */
 
  while ((r = fgets(line, sizeof(line), fp_in)))
  {
    if ((*line == '=') || mutt_strn_equal(line, "-----END", 8))
      break;
  }
  if (!r)
  {
    mutt_debug(LL_DEBUG1, "Can't find end of ASCII armor\n");
    return;
  }
 
  LOFF_T end = ftello(fp_in) - strlen(line);
  if (end < start)
  {
    mutt_debug(LL_DEBUG1, "end < start???\n");
    return;
  }
 
  if (!mutt_file_seek(fp_in, start, SEEK_SET))
  {
    return;
  }
 
  mutt_decode_base64(&state, end - start, false, ICONV_T_INVALID);
}

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pgp_mic_from_packet()

static short pgp_mic_from_packet ( unsigned char * p, size_t len )

static

Get the hash algorithm from a PGP packet.

Parameters

p	PGP packet
len	Length of packet

Return values

num	Hash algorithm id

Definition at line 152 of file pgpmicalg.c.

{
  /* is signature? */
  if ((p[0] & 0x3f) != PT_SIG)
  {
    mutt_debug(LL_DEBUG1, "tag = %d, want %d\n", p[0] & 0x3f, PT_SIG);
    return -1;
  }
 
  if ((len >= 18) && (p[1] == 3))
  {
    /* version 3 signature */
    return (short) p[17];
  }
  else if ((len >= 5) && (p[1] == 4))
  {
    /* version 4 signature */
    return (short) p[4];
  }
  else
  {
    mutt_debug(LL_DEBUG1, "Bad signature packet\n");
    return -1;
  }
}

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pgp_find_hash()

static short pgp_find_hash ( const char * fname )

static

Find the hash algorithm of a file.

Parameters

fname

File to read

Return values

num	Hash algorithm id

Definition at line 183 of file pgpmicalg.c.

{
  size_t l;
  short rc = -1;
 
  FILE *fp_in = NULL;
  FILE *fp_out = mutt_file_mkstemp();
  if (!fp_out)
  {
    mutt_perror(_("Can't create temporary file"));
    goto bye;
  }
 
  fp_in = mutt_file_fopen(fname, "r");
  if (!fp_in)
  {
    mutt_perror("%s", fname);
    goto bye;
  }
 
  pgp_dearmor(fp_in, fp_out);
  rewind(fp_out);
 
  unsigned char *p = pgp_read_packet(fp_out, &l);
  if (p)
  {
    rc = pgp_mic_from_packet(p, l);
  }
  else
  {
    mutt_debug(LL_DEBUG1, "No packet\n");
  }
 
bye:
  mutt_file_fclose(&fp_in);
  mutt_file_fclose(&fp_out);
  pgp_release_packet();
  return rc;
}

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pgp_micalg()

const char * pgp_micalg

(

const char *

fname

)

Find the hash algorithm of a file.

Parameters

fname

File to read

Return values

ptr	Name of hash algorithm

Definition at line 228 of file pgpmicalg.c.

{
  return pgp_hash_to_micalg(pgp_find_hash(fname));
}

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Variable Documentation

HashAlgorithms

const struct HashAlgorithm HashAlgorithms[]

static

Initial value:

= {
  { 1, "pgp-md5" },     { 2, "pgp-sha1" },     { 3, "pgp-ripemd160" },
  { 5, "pgp-md2" },     { 6, "pgp-tiger192" }, { 7, "pgp-haval-5-160" },
  { 8, "pgp-sha256" },  { 9, "pgp-sha384" },   { 10, "pgp-sha512" },
  { 11, "pgp-sha224" }, { -1, NULL },
}

PGP Hashing algorithms.

Definition at line 52 of file pgpmicalg.c.

                                                     {
  { 1, "pgp-md5" },     { 2, "pgp-sha1" },     { 3, "pgp-ripemd160" },
  { 5, "pgp-md2" },     { 6, "pgp-tiger192" }, { 7, "pgp-haval-5-160" },
  { 8, "pgp-sha256" },  { 9, "pgp-sha384" },   { 10, "pgp-sha512" },
  { 11, "pgp-sha224" }, { -1, NULL },
};