bin/149412: bdes in CFB/OFB modes can't decrypt own output

[Alan Hughes]

>Number:         149412
>Category:       bin
>Synopsis:       bdes in CFB/OFB modes can't decrypt own output
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Aug 08 07:20:04 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Alan Hughes
>Release:        8.1 amd64/i386
>Organization:
n/a
>Environment:
multiple, including release 8.1 amd64 CD in fixit environment
also tested several stable amd64 and i386 with same results
>Description:
encrypted output from bdes on CFB or OFB modes does not decrypt with bdes. For some combinations of plaintext/key/mode/length decryption dumps core, all others merely fail 'nicely'.
CBC(default) and ECB modes are unaffected.
labeled non-critical/low-priority as these would be rarely used modes.
>How-To-Repeat:
opt='-f 64 -k $key' ;key=0x$(md5 -qs "testpass") ;echo "plaintext for testing bdes" |bdes $opt |bdes -d $opt

replacing "-f 64" with -F or -o and other suitable length
>Fix:
don't use CFB or OFB modes.

>Release-Note:
>Audit-Trail:
>Unformatted: