Add X9.42 KDF.

Move the KDF code for CMS DH key agreement into an EVP_KDF object.
There are 2 specifications for X9.42 KDF. This implementation uses DER for
otherinfo which embeds the KDF loop counter inside the DER object.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8898)

2 files changed, 151 insertions, 0 deletions

diff --git a/doc/man3/EVP_KDF_CTX.pod b/doc/man3/EVP_KDF_CTX.pod
index 342807fa14..3899361065 100644
--- a/doc/man3/EVP_KDF_CTX.pod
+++ b/doc/man3/EVP_KDF_CTX.pod
@@ -278,6 +278,7 @@ L<EVP_KDF_HKDF(7)>
 L<EVP_KDF_SS(7)>
 L<EVP_KDF_SSHKDF(7)>
 L<EVP_KDF_X963(7)>
+L<EVP_KDF_X942KDF(7)>
 
 =head1 HISTORY
 
diff --git a/doc/man7/EVP_KDF_X942.pod b/doc/man7/EVP_KDF_X942.pod
new file mode 100644
index 0000000000..306ab2e48e
--- /dev/null
+++ b/doc/man7/EVP_KDF_X942.pod
@@ -0,0 +1,150 @@
+=pod
+
+=head1 NAME
+
+EVP_KDF_X942 - The X9.42-2001 asn1 EVP_KDF implementation
+
+=head1 DESCRIPTION
+
+The EVP_KDF_X942 algorithm implements the key derivation function (X942KDF).
+X942KDF is used by Cryptographic Message Syntax (CMS) for DH KeyAgreement, to
+derive a key using input such as a shared secret key and other info. The other
+info is DER encoded data that contains a 32 bit counter.
+
+=head2 Numeric identity
+
+B<EVP_KDF_X942> 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_UKM>
+
+This control expects two arguments: C<unsigned char *ukm>, C<size_t ukmlen>
+
+An optional random string that is provided by the sender called "partyAInfo".
+In CMS this is the user keying material.
+
+EVP_KDF_ctrl_str() takes two type strings for this control:
+
+=over 4
+
+=item "ukm"
+
+The value string is used as is.
+
+=item "hexukm"
+
+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_CEK_ALG>
+
+This control expects one argument: C<char *alg>
+
+The CEK wrapping algorithm name. 
+
+EVP_KDF_ctrl_str() type string: "cekalg"
+
+The value string is used as is.
+
+=back
+
+=head1 NOTES
+
+A context for X942KDF can be obtained by calling:
+
+EVP_KDF_CTX *kctx = EVP_KDF_CTX_new_id(EVP_KDF_X942);
+
+The output length of an X942KDF is specified via the C<keylen>
+parameter to the L<EVP_KDF_derive(3)> function.
+
+=head1 EXAMPLE
+
+This example derives 24 bytes, with the secret key "secret" and a random user
+keying material:
+
+  EVP_KDF_CTX *kctx;
+  unsigned char out[192/8];
+  unsignred char ukm[64];
+
+  if (RAND_bytes(ukm, sizeof(ukm)) <= 0)
+      error("RAND_bytes");
+
+  kctx = EVP_KDF_CTX_new_id(EVP_KDF_X942);
+  if (kctx == NULL)
+      error("EVP_KDF_CTX_new_id");
+
+  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_UKM, ukm, sizeof(ukm)) <= 0)
+      error("EVP_KDF_CTRL_SET_UKM");
+  if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_CEK_ALG,
+                   SN_id_smime_alg_CMS3DESwrap) <= 0)
+      error("EVP_KDF_CTRL_SET_CEK_ALG");
+  if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0)
+      error("EVP_KDF_derive");
+
+  EVP_KDF_CTX_free(kctx);
+
+=head1 CONFORMING TO
+
+RFC 2631
+
+=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