Add CHANGES.md and NEWS.md entries for multi-key derivation

Record the new EVP_KDF_derive_SKEYs() API and its provider interface for
the 4.2 release notes.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: beldmit

CHANGES.md

@@ -33,6 +33,20 @@ OpenSSL 4.2
 
 ### Changes between 4.1 and 4.2 [xx XXX xxxx]
 
+ * Added support for deriving several symmetric keys and IVs from a single
+   KDF operation. `EVP_KDF_derive_SKEYs()` performs the derivation and
+   `EVP_KDF_CTX_get1_SKEY()` and `EVP_KDF_CTX_get0_IV()` collect the
+   individual results by purpose, for example "client_cipher_key" or
+   "server_iv". TLS1-PRF and TLS13-KDF implement it, so a TLS 1.2 key block
+   can be produced in one call. The caller names the cipher and MAC the keys
+   are for and the provider chooses the key type accordingly, which lets a
+   provider holding its keys on a token derive them all in a single
+   operation without ever exposing the raw bytes. Providers implement this
+   through the new `OSSL_FUNC_kdf_derive_multi()` and its companion
+   functions.
+
+   *Dmitry Belyavskiy*
+
  * `X509_OBJECT_up_ref_count()` has been deprecated. Despite its name,
    X509_OBJECT_up_ref_count() does not reference count the X509_OBJECT itself.
    With X509_OBJECT being opaque there is nothing useful an application can do

NEWS.md

@@ -32,6 +32,10 @@ OpenSSL 4.2
   * Added support for Java keytool PKCS#12 files with symmetric keys.
     New API `PKCS12_parse_ex()` with `PKCS12_PARSE_CTX` has been added.
 
+  * Added support for deriving several `EVP_SKEY` objects and IVs from a
+    single KDF operation, as TLS requires. New API `EVP_KDF_derive_SKEYs()`,
+    `EVP_KDF_CTX_get1_SKEY()` and `EVP_KDF_CTX_get0_IV()` have been added.
+
 OpenSSL 4.1
 -----------