Specify the order of inputs for TLS-1.2 KDFs

From the implementation point of view does not make much difference to
constrain the input order.

We constrain it because, this way the code is easier to review, the data
flow easier to understand and the implementations in general are easier
to validate.
This commit is contained in:
Gilles Peskine 2019-05-29 17:32:39 +02:00 committed by Janos Follath
parent 8f2a6dcc25
commit ed87d31d7d

View File

@ -1244,10 +1244,11 @@
* specified in Section 5 of RFC 5246. It is based on HMAC and can be
* used with either SHA-256 or SHA-384.
*
* This key derivation algorithm uses the following inputs:
* This key derivation algorithm uses the following inputs, which must be
* passed in the order given here:
* - #PSA_KEY_DERIVATION_INPUT_SEED is the seed.
* - #PSA_KEY_DERIVATION_INPUT_SECRET is the secret key.
* - #PSA_KEY_DERIVATION_INPUT_LABEL is the label.
* - #PSA_KEY_DERIVATION_INPUT_SEED is the seed.
*
* For the application to TLS-1.2 key expansion, the seed is the
* concatenation of ServerHello.Random + ClientHello.Random,
@ -1288,10 +1289,11 @@
* The latter is based on HMAC and can be used with either SHA-256
* or SHA-384.
*
* This key derivation algorithm uses the following inputs:
* This key derivation algorithm uses the following inputs, which must be
* passed in the order given here:
* - #PSA_KEY_DERIVATION_INPUT_SEED is the seed.
* - #PSA_KEY_DERIVATION_INPUT_SECRET is the secret key.
* - #PSA_KEY_DERIVATION_INPUT_LABEL is the label.
* - #PSA_KEY_DERIVATION_INPUT_SEED is the seed.
*
* For the application to TLS-1.2, the seed (which is
* forwarded to the TLS-1.2 PRF) is the concatenation of the