RFR 8076999: SunJCE support of password-based encryption scheme 2 params (PBES2) not working

Jamil Nimeh jamil.j.nimeh at oracle.com
Tue Jul 9 16:03:28 UTC 2019

Hi Valerie, thanks for the comments:

On 7/8/2019 4:50 PM, Valerie Peng wrote:
> Hi Jamil,
> Sorry for the late reply. It's been a long while since I looked at 
> this PBES2 scheme and I need to think a few things through.
> <src/java.base/share/classes/com/sun/crypto/provider/PBES2Parameters.java>
> - line 29-30, 37, I don't see Constructor, BigInteger, and ArrayList 
> being used?
JN: I must have removed them in my local copy of the code since I posted 
the .02 webrev.  They'll be gone in this next webrev.
> - line 158: the pbes2AlgorithmNameis initialized to null. Is it our 
> intention to return null if toString() is called upon an PBES2 
> AlgorithmParameters object without init(...) call?
JN: Hmm...that's a good question.  In the case of PBES2 alg params with 
a fully qualified name (PBEWith<prf>And<cipher>) the pbes2AlgorithmName 
is initialized to whatever static class is instantiated from 
SunJCE.java.  So we don't have to worry there.  In the case of actually 
using "PBES2" (or its OID counterpart, which is more common), it looks 
like even before my changes it returned null.  What do you think about 
returning "PBES2" instead?  Once it goes through init the field will be 
set to whatever it truly is based on the DER encoding received.
> - line 176: does "keysize" means the optional keyLength field inside 
> the PBES2-params struct? Its value is from various sources. A proper 
> definition would help ensure its value is correctly set.
JN: Well, keysize does mean that, but it affects the resulting toString 
name and can also have an impact on init-time consistency checks in some 

Keysize is one of the challenging parts of this class, because it can be 
defined in multiple ways.  It can be implicit (such as in DES or 
DESede), it can be explicit by OID like it is for AES, and it can be 
defined by parameters such as in RC2 - there is one OID, no matter 
whether you do RC2_40, RC2_64 or RC2_128.  Or it can be not defined at 
all (RC5) in which case you have to assume a reasonable default (like I 
assume RC5_128) or hope that the KDF parameter segment asserts a key 
length.  So it gets set in different parts of the code depending on the 
algorithm and how it's specified.

Maybe you can expand a bit on what you're looking for by "proper 
definition" and I can try to make that happen.

> - line 207: If encoding to a DerOutputStream, why not decode using a 
> DerInputStream?
JN: There's no reason why it couldn't be done that way.  I used DerValue 
mainly because decoding in PBES2Parameters has been done with DerValue 
objects from before I started working with the code. So I kept it the 
same since it seemed to work well.
> - line 203: based on RFC3370, 5911, the preferred way for HMAC is to 
> omit the parameters instead of encoding a NULL. So, we probably should 
> not encode a null on line 203. Also, for decode, line 520 to 522 can 
> be moved here so that the decode can handle both cases, i.e. omitted 
> and present NULL, for max compatibility.
JN: From all the OpenSSL parameter blocks I've looked at, Hmac params 
will assert NULL.  There's some interesting history to 
AlgorithmIdentifier's optional parameter field when there are no 
parameters in RFC 4055, sec 2.1.  In short, a change happened in the 
1997 syntax that removed "optional" which was later fixed, but by then 
people were getting around the now mandatory field by putting NULL in 
there.  Honestly, I see NULLs asserted more commonly than it being 
omitted for message digest and HMAC AlgorithmIdentifiers.  But that 
might just be me.  According to 4055, omitting the parameters field is 
the correct way to do it, you are correct about that. Implementations 
are supposed to accept both forms.  I stuck with it because a.) we were 
already doing that and nobody was having problems with it, b.) I see 
NULL asserted more frequently so it seemed like the safer way to go.

I can try omitting it and see if openssl will accept it.  If it does 
then I can make the change permanent.  If it doesn't like it, we should 
probably leave the NULL in there.  I've got no idea how anyone else 
encodes AlgorithmIdentifiers...maybe I can play around with NSS and see 
what it does with Hmac parameters if I can find a tool that will encode 

> - line 295 - 298: if there is a comment on line 271 which explains 
> when "keyLen" is for, then we don't need this block of comment. 
> Essentially, keyLen holds that restricted key length value, right? 
> KEYLEN_ANY means no restriction whatsoever.
JN: Or it can mean that the key length is implicit (e.g. DES is always 
56 bits, so I don't need to encode it in ASN.1 and I don't need toString 
to say DES_56...DES is fine).

Maybe rather than a comment on 271, maybe a similar description for 
KEYLEN_ANY up on 154 might be a good way to go.
> - line 376: the impl of validateEncParams() seems to allow null 
> cipherParams as it returns immediately if its value is null. I am not 
> sure if we should allow null cipherParam though as this cipherParam 
> object is needed for encoding "encryptionScheme" field of the 
> PBES2-params struct. For example, if the parameters field for 
> AES_128_CBC must contain 16-byte IV, then a null cipherParams should 
> be rejected. Same goes to other encryption schemes.
JN: There are tests in the PKCS#12 family of tests that were breaking 
when I strictly enforced non-null cipherParams from the 
PBEParameterSpec.  I didn't want to risk messing up a use case in 
PKCS#12-land that didn't apply directly to what I was fixing.  What I do 
need to do is have it fail on encoding when null parameters are used, 
that will be in the next rev of the code.  I hate not being able to 
fail-fast, but it would at least remain consistent with how 
PBES2Parameters works today.
> - line 379: Since encyptionType is found using cipherAlgo and keysize 
> in the constructor, why can't we just format encryptionType.schemeName 
> as in getEncSchemeName()?
JN: Hmm...maybe we can do that.  Let me give it a try and see what happens.
> - line 419-422: Shouldn't this check be moved up to line 414, i.e. in 
> the block of code which handles the buggy encoding? Otherwise, it 
> looks like a duplicate check of line 400.
JN: I don't think so.  I think you need both.  On line 400, regardless 
of the structure (PBES2 AlgorithmIdentifier vs. PBES2-params) it must 
start with a sequence, so that check has to be there.  If it's out at 
the PBES2 AlgId layer (the error, which would manifest itself as an OID 
as the next object in the DerValue stream) then line 414 peels that away 
and what's next is your PBKDF2-params.

Line 419 has to check if the next ASN.1 structure that sits as a peer to 
PBKDF2-params is also a sequence, which it has to be, therefore the 
check on the tag is performed before sending it in to be parsed.

> - line 494, 630, 735: change the check to use KEYLEN_ANY?
JN: makes sense.
> -line 638: extra indentation?
JN: Yes, fixed.
> - line 725-752: Seems better to check the IV length before checking 
> and set the keysize.
JN: OK I can switch the order on those.
> - line 788: May return RC2_-1 or RC5_-1?
JN: Hmm...maybe in the DER parsing case, now that 
AlgorithmId/AlgorithmParameters handles the DER decoding I can't set the 
keysize as part of the parsing process any longer.  Let me take a closer 
look at it and get back to you on that one.  I think RC5 can fall into 
that trap, not sure about RC2.
> Will send you comments for the rest of webrev separately.
> Thanks,
> Valerie
> <src/java.base/share/classes/com/sun/crypto/provider/RC2Parameters.java>
> <src/java.base/share/classes/com/sun/crypto/provider/SunJCE.java>
> <src/java.base/share/classes/com/sun/crypto/provider/RC5Parameters.java>
> <test/jdk/com/sun/crypto/provider/AlgorithmParameters/PBES2Parameters.java>
> <test/jdk/com/sun/crypto/provider/AlgorithmParameters/RC5Parameters.java>
> ||
> On 6/20/2019 6:59 PM, Jamil Nimeh wrote:
>> Hello all,
>> I've updated the fix to 8076999 with the following changes:
>>   * We now use sun.security.x509.AlgorithmId and it internally uses
>>     AlgorithmParameters implementations to handle the DER encoding
>>     and decoding of encryption scheme parameters.
>>       o This means that we need to add one new standard name and some
>>         OID aliases for some AlgorithmParameters.  See the CSR link
>>         below for details.
>>   * Added a new RC5Parameter AlgorithmParameters implementation to
>>     SunJCE, plus unit tests.
>> CSR: https://bugs.openjdk.java.net/browse/JDK-8221936
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8076999
>> Webrev: http://cr.openjdk.java.net/~jnimeh/reviews/8076999/webrev.02
>> On 5/24/2019 3:51 PM, Jamil Nimeh wrote:
>>> Hello all, happy Friday!
>>> Please review the following CSR and code review.  This makes updates 
>>> to the SunJCE implementation of PBES2-based AlgorithmParameters.  
>>> Many of the details are in the CSR (see the link below).  But a 
>>> short list of the updates:
>>>   * Add DER Encode/Decode support for the following OIDS from RFC 8018:
>>>       o PRFs: HmacSHA512/224, HmacSHA512/256
>>>       o Encryption Schemes: AES-192-CBC, DES, Triple-DES, RC2, RC5
>>>   * Enforce init-time type consistency between
>>>     AlgorithmParameterSpec objects and the algorithms they are used
>>>     with (i.e. No using RC5ParameterSpec with AES-128-CBC.
>>>   * Enforce sanity checks on AlgorithmParameterSpec objects used to
>>>     init (e.g. IV length checks, integer range checks, etc.)
>>>   * Fixed a bug where explicit DER decoding of the optional key
>>>     length field in PBKDF2-params would cause the PRF to be forced
>>>     to HmacSHA1 even if the DER indicated otherwise
>>>   * Allow incoming DER encoded AlgorithmIdentifier structures to
>>>     honor the OPTIONAL qualifier on the parameters field for both
>>>     PRFs and Encryption Schemes.
>>>   * If a null encryption scheme AlgorithmParameterSpec is provided
>>>     during init time, omit the PBES2-params.encryptionScheme's
>>>     parameter segment since it is OPTIONAL per the ASN.1 from RFC 5280
>>> More details are in the CSR.
>>> CSR: https://bugs.openjdk.java.net/browse/JDK-8221936
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8076999
>>> Webrev: http://cr.openjdk.java.net/~jnimeh/reviews/8076999/webrev.01/
>>> --Jamil

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