[webauthn] clarify content of algorithm member of copedCredentialParameters

equalsJeffH has just created a new issue for 
https://github.com/w3c/webauthn:

== clarify content of algorithm member of copedCredentialParameters ==
in https://w3c.github.io/webauthn/#credential-params, the statement..
```
  The algorithm member specifies the cryptographic algorithm with 
  which the newly generated credential will be used.
```
ought to be something more akin to..
```
  The algorithm member specifies the cryptographic key generation 
  algorithm parameters with which the credential key pair MUST be 
  generated.
```
..and further refinement beyond that may be needed: 

I.e., a question is just how much of gnarly key gneration params ought
 a RP webapp be supplying, and how much does the underlying client 
platform supply?
See https://www.w3.org/TR/WebCryptoAPI/#examples-section for an 
example of the full unabridged key gen params used to generate an RSA 
key pair.  Perhaps the RP webapp **could** pass in only as much as it 
cares/needs to specify..
```
  { "name": "RSASSA-PKCS1-v1_5" }
```
..on the makeCredential() method, and the underlying platform takes 
care of the other details (i.e., modulusLength, publicExponent, and 
hash), or it could pass in..
```
  { "name": "RSASSA-PKCS1-v1_5",
     "hash":"SHA-256" }
```
..or the complete algorithmIdentifier as shown in the webcrypto spec 
example..
```
var algorithmKeyGen = {
  name: "RSASSA-PKCS1-v1_5",
  // RsaHashedKeyGenParams
  modulusLength: 2048,
  publicExponent: new Uint8Array([0x01, 0x00, 0x01]),  // Equivalent 
to 65537
  hash: {
    name: "SHA-256"
  }
};
```


Please view or discuss this issue at 
https://github.com/w3c/webauthn/issues/113 using your GitHub account

Received on Wednesday, 1 June 2016 23:14:29 UTC