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gpg: New option --force-aead

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* g10/dek.h (DEK): Turn fields use_mdc, algo_printed and symmetric
into single bit vars.  Make sure they are always set to 1 or 0.
(DEK): New field use_aead.
* g10/options.h (struct opt): New field force_aead.
* g10/pkclist.c (select_aead_from_pklist): New.
* g10/gpg.c (oForceAEAD): New const.
(opts): New options "--force-aead".
(main): Set new option.
* g10/encrypt.c (use_aead): New.
(encrypt_simple): Implement new flags DEK.use_aead.
(encrypt_crypt): Ditto.
(encrypt_filter): Ditto.
* g10/sign.c (sign_symencrypt_file): Ditto.
--

This patch should be enough to detect whether AEAD can be used.
Not tested.

Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch 2018-01-10 17:07:11 +01:00
parent 8217cd4936
commit 4e2ba546cd
No known key found for this signature in database
GPG key ID: E3FDFF218E45B72B
8 changed files with 120 additions and 20 deletions
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75
g10/encrypt.c
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@ -109,6 +109,47 @@ encrypt_seskey (DEK *dek, DEK **seskey, byte *enckey)
}
/* Return true if we shall use AEAD mode. */
int
use_aead (pk_list_t pk_list, int algo)
{
int can_use;
if (!opt.flags.rfc4880bis)
{
if (opt.force_aead)
log_info ("Warning: Option %s currently requires option '%s'\n",
"--force-aead", "--rfc4880bis");
return 0;
}
can_use = openpgp_cipher_get_algo_blklen (algo) != 16;
/* With --force-mdc we clearly do not want AEAD. */
if (opt.force_mdc)
return 0;
/* However with --force-aead we want AEAD. */
if (opt.force_aead)
{
if (!can_use)
log_info ("Warning: request to use AEAD ignored for cipher '%s'\n",
openpgp_cipher_algo_name (algo));
return 1;
}
/* AEAD does noly work with 128 bit cipher blocklength. */
if (!can_use)
return 0;
/* If all keys support AEAD we can use it. */
if (select_aead_from_pklist (pk_list))
return 1;
return 0; /* No AEAD. */
}
/* We try very hard to use a MDC */
int
use_mdc (pk_list_t pk_list,int algo)
@ -265,10 +306,15 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
log_info(_("using cipher %s\n"),
openpgp_cipher_algo_name (cfx.dek->algo));
cfx.dek->use_mdc=use_mdc(NULL,cfx.dek->algo);
if (use_aead (NULL, cfx.dek->algo))
cfx.dek->use_aead = 1;
else
cfx.dek->use_mdc = !!use_mdc (NULL, cfx.dek->algo);
}
if (do_compress && cfx.dek && cfx.dek->use_mdc
if (do_compress
&& cfx.dek
&& (cfx.dek->use_mdc || cfx.dek->use_aead)
&& is_file_compressed(filename, &rc))
{
if (opt.verbose)
@ -368,7 +414,7 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
/* Register the compress filter. */
if ( do_compress )
{
if (cfx.dek && cfx.dek->use_mdc)
if (cfx.dek && (cfx.dek->use_mdc || cfx.dek->use_aead))
zfx.new_ctb = 1;
push_compress_filter (out, &zfx, default_compress_algo());
}
@ -676,14 +722,18 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
gnupg_status_compliance_flag (CO_DE_VS),
NULL);
cfx.dek->use_mdc = use_mdc (pk_list,cfx.dek->algo);
if (use_aead (pk_list, cfx.dek->algo))
cfx.dek->use_aead = 1;
else
cfx.dek->use_mdc = !!use_mdc (pk_list, cfx.dek->algo);
/* Only do the is-file-already-compressed check if we are using a
MDC. This forces compressed files to be re-compressed if we do
not have a MDC to give some protection against chosen ciphertext
attacks. */
if (do_compress && cfx.dek->use_mdc && is_file_compressed(filename, &rc2))
* MDC or AEAD. This forces compressed files to be re-compressed if
* we do not have a MDC to give some protection against chosen
* ciphertext attacks. */
if (do_compress
&& (cfx.dek->use_mdc || cfx.dek->use_aead)
&& is_file_compressed (filename, &rc2))
{
if (opt.verbose)
log_info(_("'%s' already compressed\n"), filename);
@ -777,7 +827,7 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
/* Algo 0 means no compression. */
if (compr_algo)
{
if (cfx.dek && cfx.dek->use_mdc)
if (cfx.dek && (cfx.dek->use_mdc || cfx.dek->use_aead))
zfx.new_ctb = 1;
push_compress_filter (out,&zfx,compr_algo);
}
@ -887,7 +937,10 @@ encrypt_filter (void *opaque, int control,
efx->cfx.dek->algo = opt.def_cipher_algo;
}
efx->cfx.dek->use_mdc = use_mdc (efx->pk_list,efx->cfx.dek->algo);
if (use_aead (efx->pk_list, efx->cfx.dek->algo))
efx->cfx.dek->use_aead = 1;
else
efx->cfx.dek->use_mdc = !!use_mdc (efx->pk_list,efx->cfx.dek->algo);
make_session_key ( efx->cfx.dek );
if (DBG_CRYPTO)