diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/gpg.texi | 9 | ||||
| -rw-r--r-- | g10/mainproc.c | 13 | ||||
| -rw-r--r-- | tests/openpgp/defs.scm | 1 |
3 files changed, 11 insertions, 12 deletions
diff --git a/doc/gpg.texi b/doc/gpg.texi index 956ea4dee..49a708a3e 100644 --- a/doc/gpg.texi +++ b/doc/gpg.texi @@ -3182,10 +3182,11 @@ to ignore CRC errors. @item --ignore-mdc-error @opindex ignore-mdc-error This option changes a MDC integrity protection failure into a warning. -This can be useful if a message is partially corrupt, but it is -necessary to get as much data as possible out of the corrupt message. -However, be aware that a MDC protection failure may also mean that the -message was tampered with intentionally by an attacker. +It is required to decrypt old messages which did not use an MDC. It +may also be useful if a message is partially garbled, but it is +necessary to get as much data as possible out of that garbled message. +Be aware that a missing or failed MDC can be an indication of an +attack. Use with caution. @item --allow-weak-digest-algos @opindex allow-weak-digest-algos diff --git a/g10/mainproc.c b/g10/mainproc.c index fc5b9e556..5cf15151f 100644 --- a/g10/mainproc.c +++ b/g10/mainproc.c @@ -649,15 +649,12 @@ proc_encrypted (CTX c, PACKET *pkt) ; else if (!result && !opt.ignore_mdc_error - && !pkt->pkt.encrypted->mdc_method - && openpgp_cipher_get_algo_blklen (c->dek->algo) != 8 - && c->dek->algo != CIPHER_ALGO_TWOFISH) + && !pkt->pkt.encrypted->mdc_method) { - /* The message has been decrypted but has no MDC despite that a - modern cipher (blocklength != 64 bit, except for Twofish) is - used and the option to ignore MDC errors is not used: To - avoid attacks changing an MDC message to a non-MDC message, - we fail here. */ + /* The message has been decrypted but does not carry an MDC. + * The option --ignore-mdc-error has also not been used. To + * avoid attacks changing an MDC message to a non-MDC message, + * we fail here. */ log_error (_("WARNING: message was not integrity protected\n")); if (opt.verbose > 1) log_info ("decryption forced to fail\n"); diff --git a/tests/openpgp/defs.scm b/tests/openpgp/defs.scm index 95376521d..7e41d19bf 100644 --- a/tests/openpgp/defs.scm +++ b/tests/openpgp/defs.scm @@ -341,6 +341,7 @@ "no-auto-key-retrieve" "no-auto-key-locate" "allow-weak-digest-algos" + "ignore-mdc-error" (if have-opt-always-trust "no-auto-check-trustdb" "#no-auto-check-trustdb") (string-append "agent-program " |