RFR: 8330842: Support AES CBC with Ciphertext Stealing (CTS) in SunPKCS11 [v2]

[Valerie Peng]

On Fri, 24 May 2024 11:42:37 GMT, Francisco Ferrari Bihurriet <fferrari at openjdk.org> wrote:

>> Hi,
>> 
>> I would like to propose an implementation to support AES CBC with Ciphertext Stealing (CTS) in SunPKCS11, according to what has been specified in [JDK-8330843 CSR](https://bugs.openjdk.org/browse/JDK-8330843).
>> 
>> What follows are implementation notes that describe the most relevant aspects of the proposed change.
>> 
>> ### Buffering
>> 
>> A buffering mechanism was implemented so PKCS #​11 tokens only receive multipart input updates (`C_EncryptUpdate` or `C_DecryptUpdate`) in multiples of the block size. This mechanism protects against tokens —such as NSS— that assume an update with data not multiple of the block size is final and do variant ordering between the last 2 blocks, returning an incorrect partial output and resetting state. For example, when encrypting, a token may receive an update with an input not multiple of the block size and prematurely finalize the operation returning the last two blocks of ciphertext according to its ordering. By buffering on the Java side, the token is not aware of the end of the stream during updates and SunPKCS11 retains full control to do the last two blocks at `C_EncryptFinal` or `C_DecryptFinal`. A bug in NSS (see [1823875](https://bugzilla.mozilla.org/show_bug.cgi?id=1823875#c2)) requires buffering three blocks instead of two. If this bug gets fixed, the three block b
 uffering will still work and allow it to support old versions of the NSS library.
>> 
>> ### `implUpdate` implementation
>> 
>> The code added to `P11Cipher::implUpdate` follows the existing three-stage strategy: 1) Process data in the `padBuffer`, 2) Process data in the input and 3) Buffer to `padBuffer`. Stage #​1 for CTS has some additional complexity that is worth describing in this section.
>> 
>> The stage begins by calculating the total data available (what is already buffered in `padBuffer` + the new input) and assigning this value to the variable `totalInLen`. `newPadBufferLen` is the number of bytes that must be buffered at the end of the update operation, irrespective of where they come from (`padBuffer` or input). This number of bytes is determined out of `totalInLen` and based on the fact that each operation must retain bytes from the last two —or three, for NSS— blocks in `padBuffer`, or retain whatever is available if less than that. `dataForP11Update` is the number of bytes to be passed to the token during the operation (`C_EncryptUpdate` or `C_DecryptUpdate` calls), irrespective of the stage in which they are passed and of the dat...
>
> Francisco Ferrari Bihurriet has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:
> 
>  - Revert re-arrangement of native methods parameters
>    
>    This reverts commit 0a777e94229723376e1264e87cbf0ba805dc736f, except for
>    the copyright which is retained as 2024.
>    
>    NOTE: new calls of the same methods are retained in the re-arrangement
>    style, as we didn't introduce this re-arrangement, it was already
>    present in most of the calls inside ::implUpdate() and ::implDoFinal().
>    
>    Co-authored-by: Francisco Ferrari <fferrari at redhat.com>
>    Co-authored-by: Martin Balao <mbalao at redhat.com>
>  - Merge 'openjdk/master' into JDK-8330843
>  - 8330842: Add AES CBC with Ciphertext Stealing (CTS) SunPKCS11 tests
>    
>    Co-authored-by: Francisco Ferrari <fferrari at redhat.com>
>    Co-authored-by: Martin Balao <mbalao at redhat.com>
>  - 8330842: Support AES CBC with Ciphertext Stealing (CTS) in SunPKCS11
>    
>    Co-authored-by: Francisco Ferrari <fferrari at redhat.com>
>    Co-authored-by: Martin Balao <mbalao at redhat.com>
>  - Fix cipher tests logging
>    
>    Co-authored-by: Francisco Ferrari <fferrari at redhat.com>
>    Co-authored-by: Martin Balao <mbalao at redhat.com>
>  - Implement integer constants as enum
>    
>    Co-authored-by: Francisco Ferrari <fferrari at redhat.com>
>    Co-authored-by: Martin Balao <mbalao at redhat.com>
>  - Arrange parameters of native methods evenly
>    
>    C_EncryptUpdate / C_DecryptUpdate / C_EncryptFinal / C_DecryptFinal
>    
>    If the call doesn't fit on a single line, use the following order:
>         long hSession,
>      [  long directIn,  byte[] in,  int inOfs,  int inLen,  ]
>         long directOut, byte[] out, int outOfs, int outLen
>    
>    [ ]: optional, not present in C_EncryptFinal / C_DecryptFinal
>    
>    Co-authored-by: Francisco Ferrari <fferrari at redhat.com>
>    Co-authored-by: Martin Balao <mbalao at redhat.com>

Well, I am somewhat concerned about the incompatibility between the CTS support in SunJCE provider (CS3) and the ambiguity of CTS support in various PKCS11 libraries. The default for PKCS11 is CS1 which is based on NSS but may not apply to other PKCS11 libraries. Also, if SunPKCS11 provider (using NSS) is placed before the SunJCE provider, wouldn't this lead to unexpected failure since they are using different variation? Instead of enabling CTS support by default, maybe we should only enable it when the configuration has the variation attribute set since users are required to know which CTS variation the underlying PKCS11 library implements...

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PR Comment: https://git.openjdk.org/jdk/pull/18898#issuecomment-2136402132