Hello Thomas, et al.,

On 3/26/2018 1:49 PM, Jamil Nimeh wrote:
Hi Thomas, thanks for the feedback

 1. Were there guidelines?  Not really, though I looked at other
    parameter definitions in com.sun.crypto.provider and tried to
    follow along the same lines that they do.  One thing that should
    be changed is the LINE_SEP assignment shouldn't be an explicit
    getProperty call.  I noticed most are doing System.lineSeparator()
    so I'll change my implementation to match that.  None of these
    params appear to stringify as json, so I'll probably keep things
    consistent with the other parameter output.
 2. You make a fair point with respect to a null SecureRandom. I can
    make that spec change.
 3. Let me think on this one - I shied away from ChaCha20ParameterSpec
    for AEAD mode only because you have this nonce field that is set
    but gets ignored.  But making ChaCha20ParameterSpec an
    IvParameterSpec potentially runs into the same issue were it used
    for a ChaCha20-Poly1305 cipher. If I had to choose between the two
    I think I'd go with allowing ChaCha20ParameterSpec to be used with
    CC20-P1305 rather than making it a subclass of IvParameterSpec. 
    Doing the former helps from a type safety perspective that you
    couldn't use a ChaCha20ParameterSpec with other Ciphers that
    require an IvParameterSpec.  I know I had some discussions early
    on in the design where we talked about this, I need to refresh my
    memory as to why we didn't allow it.

Finally getting back to #3.  Took me a while to find early discussions on this.  The primary objection to ChaCha20ParameterSpec being used with ChaCha20-Poly1305 (as opposed to plain old ChaCha20) has to do with the configurable block counter.  You have this parameter that is not used, and consumption of this type of AlgorithmParameterSpec then leaves it to documentation to define what happens (is it ignored?  Used despite what the spec says?  Set to some default value regardless of what the caller sets there?). Using IvParameterSpec with ChaCha20-Poly1305 is more clear because it only allows the caller what they need to get CC20/P1305 going, the nonce.  Respectfully, I would like to keep this as-is.


On 3/26/2018 12:45 PM, Thomas Lußnig wrote:

Hi Jamil,

1) where there any guidelines about how the engineToString should be formatted ? I ask because i wondering why we need two new lines with access to the System property. If it is represented as single line json no need to line break would be needed.

Gruß Thomas

/** * Creates a formatted string describing the parameters. * * @return a string representation of the ChaCha20 parameters. */ @Override protected String engineToString() { String LINE_SEP = System.getProperty("line.separator"); HexDumpEncoder encoder = new HexDumpEncoder(); StringBuilder sb = new StringBuilder(LINE_SEP + "nonce:" + LINE_SEP + "[" + encoder.encodeBuffer(nonce) + "]"); return sb.toString(); }
2) I do not think it is an good idea to say no secureRandom=null will cause IV 
to be null.
    I see here the risk of weak implementations. I would suggest to throw an 
Exception to
    enforce secure usages. If someone really want an insecure IV he can provide 
am SecureRandom
    implementation retuning 0 only or an matching IV.

      * @param random a {@code SecureRandom} implementation.  If {@code null}
      *      is used for the random object, then a nonce consisting of all
      *      zero bytes will be used.  Otherwise a random nonce will be
      *      used.

3) If ChaCha20ParameterSpec would extends IvParameterSpec if would be valid for 
booth modes in engineInit.
     Even if the counter is not needed.
     As an alternative i would allow ChaCha20ParameterSpec also for AEAD mode.

Grup Thomas
On 3/26/2018 9:08 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.



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