>       From: [email protected] On Behalf Of Chenchu, Rakesh R
>       Sent: Thursday, 26 May, 2011 14:46

>       Recently we identified a following issue when snmpwalk is being done
on some tables:

>       The problem is in freebsd crypto function - EVP_DecryptFinal_ex().

>       (n == 0) is a valid case for some OIDs.

No it's not. When using PKCS5 padding, which is what 
this is checking (and is the default), 0 is illegal.

>       I have ... [output before DecryptFinal] <compressed>
>       Rakesh final:21 1 25 1 1 0 5 0    <---- last byte (n==0)   

>       This is working tables :
>       Rakesh final:5 0 6 6 6 6 6 6   <---- (n==6)

>       Your thoughts?

That 5,0 is apparently an ASN.1 NULL encoded after your OID (snipped).
Thus the 0 is part of the plaintext, not padding.

Either the encryptor is not padding correctly for the n=8 
(= exact block for DES) case, or something along the path is 
dropping the last block of ciphertext (which here is all padding).



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