mirror of git://git.gnupg.org/gnupg.git
gpg: Remove MDC options
* g10/gpg.c: Tuen options --force-mdc, --no-force-mdc, --disable-mdc and --no-disable-mdc into NOPs. * g10/encrypt.c (use_mdc): Simplify. MDC is now almost always used. (use_aead): Ignore MDC options. Print warning for missing MDC feature flags. * g10/pkclist.c (warn_missing_mdc_from_pklist): Rename to ... (warn_missing_aead_from_pklist): this and adjust. -- The MDC is now always used except with --rfc2440 which will lead to a a big fat warning. Signed-off-by: Werner Koch <wk@gnupg.org>
This commit is contained in:
Werner Koch
parent
af4a5dbe57
commit
253e8bdd90
29
doc/gpg.texi
29
doc/gpg.texi
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@ -2596,21 +2596,18 @@ modern and faster way to do authenticated encrytion than the old MDC
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method. See also options @option{--aead-algo} and
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@option{--chunk-size}.
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This option requires the use of option @option{--rfc4880bis} to
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declare that a not yet standardized feature is used.
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As of now this option requires the use of option @option{--rfc4880bis}
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to declare that a not yet standardized feature is used.
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@item --force-mdc
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@itemx --disable-mdc
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@opindex force-mdc
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Force the use of encryption with a modification detection code. This
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is always used with the newer ciphers (those with a blocksize greater
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than 64 bits), or if all of the recipient keys indicate MDC support in
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their feature flags.
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@item --disable-mdc
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@opindex disable-mdc
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Disable the use of the modification detection code. Note that by
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using this option, the encrypted message becomes vulnerable to a
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message modification attack.
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These options are obsolete and have no effect since GnuPG 2.2.8. The
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MDC is always used unless the keys indicate that an AEAD algorithm can
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be used in which case AEAD is used. But note: If the creation or of a
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legacy non-MDC message is exceptionally required, the option
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@option{--rfc2440} allows for this.
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@item --disable-signer-uid
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@opindex disable-signer-uid
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@ -2740,7 +2737,10 @@ keys or data may not be usable with future GnuPG versions.
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@item --rfc2440
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@opindex rfc2440
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Reset all packet, cipher and digest options to strict RFC-2440
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behavior.
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behavior. Note that by using this option encryption packets are
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created in a legacy mode without MDC protection. This is dangerous
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and should thus only be used for experiments. See also option
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@option{--ignore-mdc-error}.
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@item --pgp6
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@opindex pgp6
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@ -2750,8 +2750,9 @@ restricts you to the ciphers IDEA (if the IDEA plugin is installed),
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compression algorithms none and ZIP. This also disables
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@option{--throw-keyids}, and making signatures with signing subkeys as PGP 6
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does not understand signatures made by signing subkeys.
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FIXME: remove this options.
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This option implies @option{--disable-mdc --escape-from-lines}.
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This option implies @option{--escape-from-lines}.
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@item --pgp7
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@opindex pgp7
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@ -3234,7 +3235,7 @@ It is required to decrypt old messages which did not use an MDC. It
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may also be useful if a message is partially garbled, but it is
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necessary to get as much data as possible out of that garbled message.
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Be aware that a missing or failed MDC can be an indication of an
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attack. Use with caution.
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attack. Use with great caution; see also option @option{--rfc2440}.
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@item --allow-weak-digest-algos
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@opindex allow-weak-digest-algos
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@ -33,6 +33,7 @@
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#include "packet.h"
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#include "options.h"
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#include "main.h"
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#include "../common/i18n.h"
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#include "../common/status.h"
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@ -66,8 +67,9 @@ write_header (cipher_filter_context_t *cfx, iobuf_t a)
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}
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else
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{
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log_info ("WARNING: "
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"encrypting without integrity protection is dangerous\n");
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log_info (_("WARNING: "
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"encrypting without integrity protection is dangerous\n"));
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log_info (_("Hint: Do not use option %s\n"), "--rfc2440");
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}
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write_status_printf (STATUS_BEGIN_ENCRYPTION, "%d %d",
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@ -212,11 +212,7 @@ use_aead (pk_list_t pk_list, int algo)
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can_use = openpgp_cipher_get_algo_blklen (algo) == 16;
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/* With --force-mdc we clearly do not want AEAD. */
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if (opt.force_mdc)
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return 0;
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/* However with --force-aead we want AEAD. */
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/* With --force-aead we want AEAD. */
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if (opt.force_aead)
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{
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if (!can_use)
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@ -232,62 +228,29 @@ use_aead (pk_list_t pk_list, int algo)
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if (!can_use)
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return 0;
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/* Note the user which keys have no AEAD feature flag set. */
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if (opt.verbose)
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warn_missing_aead_from_pklist (pk_list);
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/* If all keys support AEAD we can use it. */
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return select_aead_from_pklist (pk_list);
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}
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/* We try very hard to use a MDC */
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/* Shall we use the MDC? Yes - unless rfc-2440 compatibility is
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* requested. */
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int
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use_mdc (pk_list_t pk_list,int algo)
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{
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/* RFC-2440 don't has MDC */
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(void)pk_list;
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(void)algo;
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/* RFC-2440 don't has MDC - this is the only way to create a legacy
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* non-MDC encryption packet. */
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if (RFC2440)
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return 0;
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/* --force-mdc overrides --disable-mdc */
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if(opt.force_mdc)
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return 1;
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if(opt.disable_mdc)
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return 0;
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/* Do the keys really support MDC? */
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if(select_mdc_from_pklist(pk_list))
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return 1;
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/* The keys don't support MDC, so now we do a bit of a hack - if any
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of the AESes or TWOFISH are in the prefs, we assume that the user
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can handle a MDC. This is valid for PGP 7, which can handle MDCs
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though it will not generate them. 2440bis allows this, by the
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way. */
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if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
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CIPHER_ALGO_AES,NULL)==CIPHER_ALGO_AES)
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return 1;
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if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
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CIPHER_ALGO_AES192,NULL)==CIPHER_ALGO_AES192)
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return 1;
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if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
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CIPHER_ALGO_AES256,NULL)==CIPHER_ALGO_AES256)
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return 1;
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if(select_algo_from_prefs(pk_list,PREFTYPE_SYM,
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CIPHER_ALGO_TWOFISH,NULL)==CIPHER_ALGO_TWOFISH)
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return 1;
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/* Last try. Use MDC for the modern ciphers. */
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if (openpgp_cipher_get_algo_blklen (algo) != 8)
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return 1;
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if (opt.verbose)
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warn_missing_mdc_from_pklist (pk_list);
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return 0; /* No MDC */
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return 1; /* In all other cases we use the MDC */
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}
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21
g10/gpg.c
21
g10/gpg.c
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@ -301,10 +301,6 @@ enum cmd_and_opt_values
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oShowPhotos,
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oNoShowPhotos,
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oPhotoViewer,
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oForceMDC,
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oNoForceMDC,
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oDisableMDC,
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oNoDisableMDC,
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oForceAEAD,
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oS2KMode,
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oS2KDigest,
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@ -605,11 +601,6 @@ static ARGPARSE_OPTS opts[] = {
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ARGPARSE_s_n (oQuiet, "quiet", "@"),
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ARGPARSE_s_n (oNoTTY, "no-tty", "@"),
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ARGPARSE_s_n (oForceMDC, "force-mdc", "@"),
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ARGPARSE_s_n (oNoForceMDC, "no-force-mdc", "@"),
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ARGPARSE_s_n (oDisableMDC, "disable-mdc", "@"),
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ARGPARSE_s_n (oNoDisableMDC, "no-disable-mdc", "@"),
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ARGPARSE_s_n (oForceAEAD, "force-aead", "@"),
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ARGPARSE_s_n (oDisableSignerUID, "disable-signer-uid", "@"),
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@ -924,6 +915,11 @@ static ARGPARSE_OPTS opts[] = {
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ARGPARSE_s_n (oNoop, "force-v4-certs", "@"),
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ARGPARSE_s_n (oNoop, "no-force-v4-certs", "@"),
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ARGPARSE_s_n (oNoop, "no-mdc-warning", "@"),
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ARGPARSE_s_n (oNoop, "force-mdc", "@"),
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ARGPARSE_s_n (oNoop, "no-force-mdc", "@"),
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ARGPARSE_s_n (oNoop, "disable-mdc", "@"),
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ARGPARSE_s_n (oNoop, "no-disable-mdc", "@"),
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ARGPARSE_end ()
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};
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@ -2201,7 +2197,6 @@ set_compliance_option (enum cmd_and_opt_values option)
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case oDE_VS:
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set_compliance_option (oOpenPGP);
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opt.compliance = CO_DE_VS;
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opt.force_mdc = 1;
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opt.def_aead_algo = 0;
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/* Fixme: Change other options. */
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break;
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@ -3019,11 +3014,6 @@ main (int argc, char **argv)
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break;
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case oPhotoViewer: opt.photo_viewer = pargs.r.ret_str; break;
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case oForceMDC: opt.force_mdc = 1; break;
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case oNoForceMDC: opt.force_mdc = 0; break;
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case oDisableMDC: opt.disable_mdc = 1; break;
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case oNoDisableMDC: opt.disable_mdc = 0; break;
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case oForceAEAD: opt.force_aead = 1; break;
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case oDisableSignerUID: opt.flags.disable_signer_uid = 1; break;
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@ -3802,7 +3792,6 @@ main (int argc, char **argv)
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{
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/* That does not anymore work because we have no more support
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for v3 signatures. */
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opt.disable_mdc=1;
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opt.escape_from=1;
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opt.ask_sig_expire=0;
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}
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@ -236,7 +236,7 @@ int select_algo_from_prefs( PK_LIST pk_list, int preftype,
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int request, const union pref_hint *hint);
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int select_mdc_from_pklist (PK_LIST pk_list);
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aead_algo_t select_aead_from_pklist (pk_list_t pk_list);
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void warn_missing_mdc_from_pklist (PK_LIST pk_list);
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void warn_missing_aead_from_pklist (PK_LIST pk_list);
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void warn_missing_aes_from_pklist (PK_LIST pk_list);
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/*-- skclist.c --*/
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@ -1677,9 +1677,10 @@ select_aead_from_pklist (PK_LIST pk_list)
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}
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/* Print a warning for all keys in PK_LIST missing the MDC feature. */
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/* Print a warning for all keys in PK_LIST missing the AEAD feature
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* flag or AEAD algorithms. */
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void
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warn_missing_mdc_from_pklist (PK_LIST pk_list)
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warn_missing_aead_from_pklist (PK_LIST pk_list)
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{
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PK_LIST pkr;
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@ -1688,12 +1689,12 @@ warn_missing_mdc_from_pklist (PK_LIST pk_list)
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int mdc;
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if (pkr->pk->user_id) /* selected by user ID */
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mdc = pkr->pk->user_id->flags.mdc;
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mdc = pkr->pk->user_id->flags.aead;
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else
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mdc = pkr->pk->flags.mdc;
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mdc = pkr->pk->flags.aead;
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if (!mdc)
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log_info (_("Note: key %s has no %s feature\n"),
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keystr_from_pk (pkr->pk), "MDC");
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keystr_from_pk (pkr->pk), "AEAD");
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}
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}
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@ -75,6 +75,8 @@ g10/tofu.c
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g10/trustdb.c
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g10/trust.c
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g10/verify.c
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g10/cipher-cfb.c
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g10/cipher-aead.c
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kbx/kbxutil.c
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