EVP_KDF.pod: extend text on 'salt' and 'info' parameters

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21469)

(cherry picked from commit 61c8146aa36b84afd9d83c87c9a01138979ffd60)

diff --git a/doc/man3/EVP_KDF.pod b/doc/man3/EVP_KDF.pod
index bbff6dd41a8f9b91a4519418ef646a435d34f9e3..b291c203d825e8a302c2547cf4b806f3083fc8ab 100644 (file)
--- a/doc/man3/EVP_KDF.pod
+++ b/doc/man3/EVP_KDF.pod
@@ -191,7 +191,7 @@ For those KDF implementations that support it, this parameter sets the password.
 
 =item "salt" (B<OSSL_KDF_PARAM_SALT>) <octet string>
 
-Some KDF implementations can take a salt.
+Some KDF implementations can take a non-secret unique cryptographic salt.
 For those KDF implementations that support it, this parameter sets the salt.
 
 The default value, if any, is implementation dependent.
@@ -227,6 +227,15 @@ Some KDF implementations require a key.
 For those KDF implementations that support it, this octet string parameter
 sets the key.
 
+=item "info" (B<OSSL_KDF_PARAM_INFO>) <octet string>
+
+Some KDF implementations, such as L<EVP_KDF-HKDF(7)>, take an 'info' parameter
+for binding the derived key material
+to application- and context-specific information.
+This parameter sets the info, fixed info, other info or shared info argument.
+You can specify this parameter multiple times, and each instance will
+be concatenated to form the final value.
+
 =item "maclen" (B<OSSL_KDF_PARAM_MAC_SIZE>) <unsigned integer>
 
 Used by implementations that use a MAC with a variable output size (KMAC).