RFR: ChaCha20 and ChaCha20/Poly1305 Cipher implementations

Jamil Nimeh jamil.j.nimeh at oracle.com
Tue May 22 17:37:06 UTC 2018


Wow, good catch.  This is something that got left by the wayside, 
probably from one of the earliest revisions of the code when we didn't 
have an AlgorithmParameters implementation.  I'll get this fixed up 
today.  Shouldn't take too long to get this working.  I think it should 
return null if it is ChaCha20 since there's no AlgorithmParameters 
definition for ChaCha20, and return a ChaCha20Poly1305Parameters for 
ChaCha20-Poly1305.

For the latter Cipher, it shouldn't matter how you init the Cipher.  We 
can return the AP with the nonce value, however it came into being 
(random, AP or APS).

--Jamil


On 05/22/2018 10:29 AM, Sean Mullan wrote:
> Question on engineGetParameters() in ChaCha20Cipher.java:
>
>  231     protected AlgorithmParameters engineGetParameters() {
>  232         return null;
>  233     }
>
> Shouldn't this return the params that are passed into engineInit()? 
> Also, when null is passed in and the params are generated using 
> default values, this method should return those params. From 
> CipherSpi.engineInit(int opmode, Key key, SecureRandom):
>
> "The generated parameters can be retrieved using engineGetParameters 
> or engineGetIV (if the parameter is an IV)."
>
> --Sean
>
> On 5/21/18 2:36 PM, Jamil Nimeh wrote:
>> And the fun just keeps going!  Round 7.
>>
>> This revision removes wrap/unwrap support for ChaCha20 and 
>> ChaCha20-Poly1305 until there is a standardized key wrapping approach 
>> for these ciphers (similar to how AES has its own key wrapping scheme 
>> in RFC 3394).
>>
>> Initializing the cipher with WRAP/UNWRAP mode will throw 
>> UnsupportedOperationException and likewise the wrap/unwrap methods 
>> will throw IllegalStateException.
>>
>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.07/
>>
>> Thanks,
>>
>> --Jamil
>>
>>
>> On 05/16/2018 12:05 PM, Jamil Nimeh wrote:
>>>
>>> Round 6.
>>>
>>> This brings ChaCha20/ChaCha20-Poly1305 into conformance with 
>>> Cipher's specification when forms of init that take 
>>> AlgorithmParameters or AlgorithmParameterSpec are used. Previously, 
>>> a non-null AP or APS object was required.  In order to better 
>>> conform to the specification, if a null AP or APS is provided for 
>>> these ciphers, a random nonce will be generated and the counter will 
>>> be set to 1, just as is currently done with valid forms of init that 
>>> don't take an AP or APS object (e.g. Cipher.init(int, Key, 
>>> SecureRandom) ). Per the spec in Cipher, this is only true for 
>>> ENCRYPT_MODE and will throw InvalidKeyException when done in 
>>> DECRYPT_MODE.
>>>
>>> I also added a few test cases that exercise these code paths in the 
>>> ChaCha20Poly1305Parameters.java test case.
>>>
>>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.06/
>>>
>>> Thanks,
>>>
>>> --Jamil
>>>
>>>
>>> On 05/04/2018 07:06 AM, Jamil Nimeh wrote:
>>>>
>>>> Round 5.
>>>>
>>>> This adds Sean's comments.  Sean, I was never able to execute a 
>>>> case on init where a half-baked object would fail.  In most cases 
>>>> it would fail in checks in javax.crypto.Cipher before it ever made 
>>>> it down to my code. I'm pretty confident the init sequence is OK.  
>>>> I did move the setting of a few data members toward the end of the 
>>>> init sequence but setting the key and nonce is necessary before 
>>>> creating the initial state, which is then used for generating an 
>>>> authentication key for AEAD mode and generating keystream.
>>>>
>>>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.05
>>>>
>>>> Also the CSR has been finalized and can be found here:
>>>> https://bugs.openjdk.java.net/browse/JDK-8198925
>>>>
>>>> --Jamil
>>>>
>>>> On 04/27/2018 02:21 PM, Jamil Nimeh wrote:
>>>>>
>>>>> Round 4 of updates for ChaCha20 and ChaCha20-Poly1305, minor stuff 
>>>>> mostly:
>>>>>
>>>>>   * Added words in the description of javax.crypto.Cipher
>>>>>     recommending callers reinitialize the Cipher to use different
>>>>>     nonces after each complete encryption or decryption (similar
>>>>>     language to what exists already for AES-GCM encryption).
>>>>>   * Added an additional test case for ChaCha20NoReuse
>>>>>   * Made accessor methods for ChaCha20ParameterSpec final and
>>>>>     cleaned up the code a bit based on comments from the field.
>>>>>
>>>>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.04/
>>>>>
>>>>> Thanks!
>>>>>
>>>>> --Jamil
>>>>>
>>>>>
>>>>> On 04/13/2018 11:59 AM, Jamil Nimeh wrote:
>>>>>> Round 3 of updates for ChaCha20 and ChaCha20-Poly1305:
>>>>>>
>>>>>> * Removed the key field in ChaCha20 and Poly1305 implementations 
>>>>>> and only retain the key bytes as an object field (thanks Thomas 
>>>>>> for catching this)
>>>>>>
>>>>>> * Added additional protections against key/nonce reuse. This is a 
>>>>>> behavioral change to ChaCha20 and ChaCha20-Poly1305.  Instances 
>>>>>> of these ciphers will no longer allow you to do subsequent 
>>>>>> doUpdate/doFinal calls after the first doFinal without 
>>>>>> re-initializing the cipher with either a new key or nonce. 
>>>>>> Attempting to reuse the cipher without a new initialization will 
>>>>>> throw an IllegalStateException.  This is similar to the behavior 
>>>>>> of AES-GCM in encrypt mode, but for ChaCha20 it needs to be done 
>>>>>> for both encrypt and decrypt.
>>>>>>
>>>>>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.03/
>>>>>>
>>>>>> Thanks,
>>>>>> --Jamil
>>>>>>
>>>>>> On 04/10/2018 03:34 PM, Jamil Nimeh wrote:
>>>>>>> Hello everyone,
>>>>>>>
>>>>>>> This is a quick update to the previous webrev:
>>>>>>>
>>>>>>> * When using the form of engineInit that does only takes op, key 
>>>>>>> and random, the nonce will always be random even if the random 
>>>>>>> parameter is null.  A default instance of SecureRandom will be 
>>>>>>> used to create the nonce in this case, instead of all zeroes.
>>>>>>>
>>>>>>> * Unused debug code was removed from the ChaCha20Cipher.java file
>>>>>>>
>>>>>>> * ChaCha20Parameters.engineToString no longer obtains the line 
>>>>>>> separator from a System property directly. It calls 
>>>>>>> System.lineSeparator() similar to how other AlgorithmParameter 
>>>>>>> classes in com.sun.crypto.provider do it.
>>>>>>>
>>>>>>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.02/
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> --Jamil
>>>>>>>
>>>>>>>
>>>>>>> On 03/26/2018 12:08 PM, Jamil Nimeh wrote:
>>>>>>>> Hello all,
>>>>>>>>
>>>>>>>> This is a request for review for the ChaCha20 and 
>>>>>>>> ChaCha20-Poly1305 cipher implementations.  Links to the webrev 
>>>>>>>> and the JEP which outlines the characteristics and behavior of 
>>>>>>>> the ciphers are listed below.
>>>>>>>>
>>>>>>>> http://cr.openjdk.java.net/~jnimeh/reviews/8153028/webrev.01/
>>>>>>>> http://openjdk.java.net/jeps/329
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> --Jamil
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>



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