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gpg: Make --require-compliance work for -se
* g10/encrypt.c (encrypt_crypt, encrypt_filter): Factor common code out to ... (create_dek_with_warnings): new (check_encryption_compliance): and new. * g10/encrypt.c (encrypt_filter): Add the compliance check. -- GnuPG-bug-id: 6174
This commit is contained in:
Werner Koch
parent
15cf36f6a8
commit
f88cb12f8e
284
g10/encrypt.c
284
g10/encrypt.c
@ -1,7 +1,7 @@
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/* encrypt.c - Main encryption driver
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* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
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* 2006, 2009 Free Software Foundation, Inc.
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* Copyright (C) 2016 g10 Code GmbH
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* Copyright (C) 2016, 2022 g10 Code GmbH
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*
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* This file is part of GnuPG.
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*
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@ -67,6 +67,65 @@ encrypt_store (const char *filename)
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}
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/* Create an setup DEK structure and print approriate warnings. The
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* FALLBACK_TO_3DES flag is used to handle the two different ways we
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* use this code. PK_LIST gives the list of public keys. Always
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* returns a DEK. The actual session needs to be added later. */
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static DEK *
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create_dek_with_warnings (int fallback_to_3des, pk_list_t pk_list)
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{
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DEK *dek;
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dek = xmalloc_secure_clear (sizeof *dek);
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if (!opt.def_cipher_algo)
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{
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/* Try to get it from the prefs. */
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dek->algo = select_algo_from_prefs (pk_list, PREFTYPE_SYM, -1, NULL);
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if (dek->algo == -1 && fallback_to_3des)
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{
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/* The only way select_algo_from_prefs can fail here is when
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* mixing v3 and v4 keys, as v4 keys have an implicit
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* preference entry for 3DES, and the pk_list cannot be
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* empty. In this case, use 3DES anyway as it's the safest
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* choice - perhaps the v3 key is being used in an OpenPGP
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* implementation and we know that the implementation behind
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* any v4 key can handle 3DES. */
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dek->algo = CIPHER_ALGO_3DES;
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}
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else if (dek->algo == -1)
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{
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/* Because 3DES is implicitly in the prefs, this can only
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* happen if we do not have any public keys in the list. */
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dek->algo = DEFAULT_CIPHER_ALGO;
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}
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/* In case 3DES has been selected, print a warning if any key
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* does not have a preference for AES. This should help to
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* indentify why encrypting to several recipients falls back to
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* 3DES. */
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if (opt.verbose && dek->algo == CIPHER_ALGO_3DES)
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warn_missing_aes_from_pklist (pk_list);
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}
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else
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{
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if (!opt.expert
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&& (select_algo_from_prefs (pk_list, PREFTYPE_SYM,
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opt.def_cipher_algo, NULL)
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!= opt.def_cipher_algo))
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{
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log_info(_("WARNING: forcing symmetric cipher %s (%d)"
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" violates recipient preferences\n"),
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openpgp_cipher_algo_name (opt.def_cipher_algo),
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opt.def_cipher_algo);
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}
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dek->algo = opt.def_cipher_algo;
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}
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return dek;
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}
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/* *SESKEY contains the unencrypted session key ((*SESKEY)->KEY) and
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the algorithm that will be used to encrypt the contents of the SED
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packet ((*SESKEY)->ALGO). If *SESKEY is NULL, then a random
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@ -212,7 +271,7 @@ encrypt_simple (const char *filename, int mode, int use_seskey)
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if ( use_seskey )
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{
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DEK *dek = NULL;
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DEK *dek = NULL; /* Dummy. */
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seskeylen = openpgp_cipher_get_algo_keylen (default_cipher_algo ());
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encrypt_seskey( cfx.dek, &dek, enckey );
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@ -446,6 +505,80 @@ write_symkey_enc (STRING2KEY *symkey_s2k, DEK *symkey_dek, DEK *dek,
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}
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/* Check whether all encryption keys are compliant with the current
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* mode and issue respective status lines. DEK has the info about the
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* session key and PK_LIST the list of public keys. */
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static gpg_error_t
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check_encryption_compliance (DEK *dek, pk_list_t pk_list)
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{
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gpg_error_t err = 0;
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pk_list_t pkr;
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int compliant;
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if (! gnupg_cipher_is_allowed (opt.compliance, 1, dek->algo,
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GCRY_CIPHER_MODE_CFB))
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{
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log_error (_("cipher algorithm '%s' may not be used in %s mode\n"),
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openpgp_cipher_algo_name (dek->algo),
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gnupg_compliance_option_string (opt.compliance));
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err = gpg_error (GPG_ERR_CIPHER_ALGO);
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goto leave;
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}
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if (!gnupg_rng_is_compliant (opt.compliance))
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{
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err = gpg_error (GPG_ERR_FORBIDDEN);
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log_error (_("%s is not compliant with %s mode\n"),
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"RNG",
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gnupg_compliance_option_string (opt.compliance));
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write_status_error ("random-compliance", err);
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goto leave;
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}
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compliant = gnupg_cipher_is_compliant (CO_DE_VS, dek->algo,
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GCRY_CIPHER_MODE_CFB);
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for (pkr = pk_list; pkr; pkr = pkr->next)
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{
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PKT_public_key *pk = pkr->pk;
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unsigned int nbits = nbits_from_pk (pk);
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if (!gnupg_pk_is_compliant (opt.compliance, pk->pubkey_algo, 0,
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pk->pkey, nbits, NULL))
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log_info (_("WARNING: key %s is not suitable for encryption"
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" in %s mode\n"),
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keystr_from_pk (pk),
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gnupg_compliance_option_string (opt.compliance));
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if (compliant
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&& !gnupg_pk_is_compliant (CO_DE_VS, pk->pubkey_algo, 0, pk->pkey,
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nbits, NULL))
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compliant = 0; /* Not compliant - reset flag. */
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}
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/* If we are compliant print the status for de-vs compliance. */
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if (compliant)
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write_status_strings (STATUS_ENCRYPTION_COMPLIANCE_MODE,
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gnupg_status_compliance_flag (CO_DE_VS),
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NULL);
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/* Check whether we should fail the operation. */
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if (opt.flags.require_compliance
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&& opt.compliance == CO_DE_VS
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&& !compliant)
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{
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log_error (_("operation forced to fail due to"
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" unfulfilled compliance rules\n"));
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err = gpg_error (GPG_ERR_FORBIDDEN);
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g10_errors_seen = 1;
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goto leave;
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}
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leave:
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return err;
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}
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/*
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* Encrypt the file with the given userids (or ask if none is
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* supplied). Either FILENAME or FILEFD must be given, but not both.
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@ -475,7 +608,6 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
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progress_filter_context_t *pfx;
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PK_LIST pk_list;
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int do_compress;
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int compliant;
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if (filefd != -1 && filename)
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return gpg_error (GPG_ERR_INV_ARG); /* Both given. */
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@ -563,109 +695,13 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
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push_armor_filter (afx, out);
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}
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/* Create a session key. */
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cfx.dek = xmalloc_secure_clear (sizeof *cfx.dek);
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if (!opt.def_cipher_algo)
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{
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/* Try to get it from the prefs. */
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cfx.dek->algo = select_algo_from_prefs (pk_list, PREFTYPE_SYM, -1, NULL);
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/* The only way select_algo_from_prefs can fail here is when
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mixing v3 and v4 keys, as v4 keys have an implicit preference
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entry for 3DES, and the pk_list cannot be empty. In this
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case, use 3DES anyway as it's the safest choice - perhaps the
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v3 key is being used in an OpenPGP implementation and we know
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that the implementation behind any v4 key can handle 3DES. */
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if (cfx.dek->algo == -1)
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{
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cfx.dek->algo = CIPHER_ALGO_3DES;
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}
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/* In case 3DES has been selected, print a warning if any key
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does not have a preference for AES. This should help to
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indentify why encrypting to several recipients falls back to
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3DES. */
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if (opt.verbose && cfx.dek->algo == CIPHER_ALGO_3DES)
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warn_missing_aes_from_pklist (pk_list);
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}
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else
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{
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if (!opt.expert
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&& (select_algo_from_prefs (pk_list, PREFTYPE_SYM,
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opt.def_cipher_algo, NULL)
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!= opt.def_cipher_algo))
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{
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log_info(_("WARNING: forcing symmetric cipher %s (%d)"
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" violates recipient preferences\n"),
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openpgp_cipher_algo_name (opt.def_cipher_algo),
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opt.def_cipher_algo);
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}
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cfx.dek->algo = opt.def_cipher_algo;
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}
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/* Check compliance. */
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if (! gnupg_cipher_is_allowed (opt.compliance, 1, cfx.dek->algo,
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GCRY_CIPHER_MODE_CFB))
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{
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log_error (_("cipher algorithm '%s' may not be used in %s mode\n"),
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openpgp_cipher_algo_name (cfx.dek->algo),
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gnupg_compliance_option_string (opt.compliance));
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rc = gpg_error (GPG_ERR_CIPHER_ALGO);
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goto leave;
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}
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if (!gnupg_rng_is_compliant (opt.compliance))
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{
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rc = gpg_error (GPG_ERR_FORBIDDEN);
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log_error (_("%s is not compliant with %s mode\n"),
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"RNG",
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gnupg_compliance_option_string (opt.compliance));
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write_status_error ("random-compliance", rc);
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goto leave;
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}
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compliant = gnupg_cipher_is_compliant (CO_DE_VS, cfx.dek->algo,
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GCRY_CIPHER_MODE_CFB);
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{
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pk_list_t pkr;
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for (pkr = pk_list; pkr; pkr = pkr->next)
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{
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PKT_public_key *pk = pkr->pk;
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unsigned int nbits = nbits_from_pk (pk);
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if (!gnupg_pk_is_compliant (opt.compliance, pk->pubkey_algo, 0,
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pk->pkey, nbits, NULL))
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log_info (_("WARNING: key %s is not suitable for encryption"
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" in %s mode\n"),
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keystr_from_pk (pk),
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gnupg_compliance_option_string (opt.compliance));
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if (compliant
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&& !gnupg_pk_is_compliant (CO_DE_VS, pk->pubkey_algo, 0, pk->pkey,
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nbits, NULL))
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compliant = 0;
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}
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}
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if (compliant)
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write_status_strings (STATUS_ENCRYPTION_COMPLIANCE_MODE,
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gnupg_status_compliance_flag (CO_DE_VS),
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NULL);
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if (opt.flags.require_compliance
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&& opt.compliance == CO_DE_VS
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&& !compliant)
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{
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log_error (_("operation forced to fail due to"
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" unfulfilled compliance rules\n"));
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rc = gpg_error (GPG_ERR_FORBIDDEN);
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g10_errors_seen = 1;
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goto leave;
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}
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/* Create a session key (a DEK). */
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cfx.dek = create_dek_with_warnings (1, pk_list);
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/* Check compliance etc. */
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rc = check_encryption_compliance (cfx.dek, pk_list);
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if (rc)
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goto leave;
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cfx.dek->use_mdc = use_mdc (pk_list,cfx.dek->algo);
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@ -842,41 +878,11 @@ encrypt_filter (void *opaque, int control,
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{
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if ( !efx->header_okay )
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{
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efx->cfx.dek = xmalloc_secure_clear ( sizeof *efx->cfx.dek );
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if ( !opt.def_cipher_algo )
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{
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/* Try to get it from the prefs. */
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efx->cfx.dek->algo =
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select_algo_from_prefs (efx->pk_list, PREFTYPE_SYM, -1, NULL);
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if (efx->cfx.dek->algo == -1 )
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{
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/* Because 3DES is implicitly in the prefs, this can
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only happen if we do not have any public keys in
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the list. */
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efx->cfx.dek->algo = DEFAULT_CIPHER_ALGO;
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}
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efx->cfx.dek = create_dek_with_warnings (0, efx->pk_list);
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/* In case 3DES has been selected, print a warning if
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any key does not have a preference for AES. This
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should help to indentify why encrypting to several
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recipients falls back to 3DES. */
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if (opt.verbose
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&& efx->cfx.dek->algo == CIPHER_ALGO_3DES)
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warn_missing_aes_from_pklist (efx->pk_list);
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}
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else
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{
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if (!opt.expert
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&& select_algo_from_prefs (efx->pk_list,PREFTYPE_SYM,
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opt.def_cipher_algo,
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NULL) != opt.def_cipher_algo)
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log_info(_("forcing symmetric cipher %s (%d) "
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"violates recipient preferences\n"),
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openpgp_cipher_algo_name (opt.def_cipher_algo),
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opt.def_cipher_algo);
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efx->cfx.dek->algo = opt.def_cipher_algo;
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}
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rc = check_encryption_compliance (efx->cfx.dek, efx->pk_list);
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if (rc)
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return rc;
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efx->cfx.dek->use_mdc = use_mdc (efx->pk_list,efx->cfx.dek->algo);
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