Added X963KDF API

X963 KDF is used for CMS ec keyagree Recipient Info.
The X963 KDF that is used by CMS EC Key Agreement has been moved
into a EVP_KDF object. This KDF is almost identical to the the SSKDF
hash variant, so it has been implemented inside the SSKDF code with
its own method table.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8902)

1 files changed, 136 insertions, 0 deletions

diff --git a/doc/man7/EVP_KDF_X963.pod b/doc/man7/EVP_KDF_X963.pod
new file mode 100644
index 0000000000..11789ae5aa
--- /dev/null
+++ b/doc/man7/EVP_KDF_X963.pod
@@ -0,0 +1,136 @@
+=pod
+
+=head1 NAME
+
+EVP_KDF_X963 - The X9.63-2001 EVP_KDF implementation
+
+=head1 DESCRIPTION
+
+The EVP_KDF_X963 algorithm implements the key derivation function (X963KDF).
+X963KDF is used by Cryptographic Message Syntax (CMS) for EC KeyAgreement, to
+derive a key using input such as a shared secret key and shared info.
+
+=head2 Numeric identity
+
+B<EVP_KDF_X963> is the numeric identity for this implementation; it
+can be used with the EVP_KDF_CTX_new_id() function.
+
+=head2 Supported controls
+
+The supported controls are:
+
+=over 4
+
+=item B<EVP_KDF_CTRL_SET_MD>
+
+This control works as described in L<EVP_KDF_CTX(3)/CONTROLS>.
+
+=item B<EVP_KDF_CTRL_SET_KEY>
+
+This control expects two arguments: C<unsigned char *secret>, C<size_t secretlen>
+
+The shared secret used for key derivation.  This control sets the secret.
+
+EVP_KDF_ctrl_str() takes two type strings for this control:
+
+=over 4
+
+=item "secret"
+
+The value string is used as is.
+
+=item "hexsecret"
+
+The value string is expected to be a hexadecimal number, which will be
+decoded before being passed on as the control value.
+
+=back
+
+=item B<EVP_KDF_CTRL_SET_SHARED_INFO>
+
+This control expects two arguments: C<unsigned char *info>, C<size_t infolen>
+
+An optional value for shared info. This control sets the shared info.
+
+EVP_KDF_ctrl_str() takes two type strings for this control:
+
+=over 4
+
+=item "info"
+
+The value string is used as is.
+
+=item "hexinfo"
+
+The value string is expected to be a hexadecimal number, which will be
+decoded before being passed on as the control value.
+
+=back
+
+=back
+
+=head1 NOTES
+
+X963KDF is very similar to the SSKDF that uses a digest as the auxilary function,
+X963KDF appends the counter to the secret, whereas SSKDF prepends the counter.
+
+A context for X963KDF can be obtained by calling:
+
+EVP_KDF_CTX *kctx = EVP_KDF_CTX_new_id(EVP_KDF_X963);
+
+The output length of an X963KDF is specified via the C<keylen>
+parameter to the L<EVP_KDF_derive(3)> function.
+
+=head1 EXAMPLE
+
+This example derives 10 bytes, with the secret key "secret" and sharedinfo
+value "label":
+
+  EVP_KDF_CTX *kctx;
+  unsigned char out[10];
+
+  kctx = EVP_KDF_CTX_new_id(EVP_KDF_X963);
+
+  if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_MD, EVP_sha256()) <= 0) {
+      error("EVP_KDF_CTRL_SET_MD");
+  }
+  if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_KEY, "secret", (size_t)6) <= 0) {
+      error("EVP_KDF_CTRL_SET_KEY");
+  }
+  if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_SHARED_INFO, "label", (size_t)5) <= 0) {
+      error("EVP_KDF_CTRL_SET_SHARED_INFO");
+  }
+  if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0) {
+      error("EVP_KDF_derive");
+  }
+
+  EVP_KDF_CTX_free(kctx);
+
+=head1 CONFORMING TO
+
+"SEC 1: Elliptic Curve Cryptography"
+
+=head1 SEE ALSO
+
+L<EVP_KDF_CTX>,
+L<EVP_KDF_CTX_new_id(3)>,
+L<EVP_KDF_CTX_free(3)>,
+L<EVP_KDF_ctrl(3)>,
+L<EVP_KDF_size(3)>,
+L<EVP_KDF_derive(3)>,
+L<EVP_KDF_CTX(3)/CONTROLS>
+
+=head1 HISTORY
+
+This functionality was added to OpenSSL 3.0.0.
+
+=head1 COPYRIGHT
+
+Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the Apache License 2.0 (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut