Add EVP_KDF-X942 to the fips module

[openssl.git] / doc / man7 / EVP_KDF-X942-ASN1.pod

diff --git a/doc/man7/EVP_KDF-X942-ASN1.pod b/doc/man7/EVP_KDF-X942-ASN1.pod
new file mode 100644 (file)
index 0000000..3c5c307
--- /dev/null
+++ b/doc/man7/EVP_KDF-X942-ASN1.pod
@@ -0,0 +1,146 @@
+=pod
+
+=head1 NAME
+
+EVP_KDF-X942-ASN1 - The X9.42-2003 asn1 EVP_KDF implementation
+
+=head1 DESCRIPTION
+
+The EVP_KDF-X942-ASN1 algorithm implements the key derivation function
+X942KDF-ASN1. It is used by 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 as well as optional fields for "partyu-info",
+"partyv-info", "supp-pubinfo" and "supp-privinfo".
+This kdf is used by Cryptographic Message Syntax (CMS).
+
+=head2 Identity
+
+"X942KDF-ASN1" or "X942KDF" is the name for this implementation; it
+can be used with the EVP_KDF_fetch() function.
+
+=head2 Supported parameters
+
+The supported parameters are:
+
+=over 4
+
+=item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
+
+=item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
+
+These parameters work as described in L<EVP_KDF(3)/PARAMETERS>.
+
+=item "key" (B<OSSL_KDF_PARAM_KEY>) <octet string>
+
+The shared secret used for key derivation.  This parameter sets the secret.
+
+=item "partyu-info" (B<OSSL_KDF_PARAM_X942_PARTYUINFO>) <octet string>
+
+An optional octet string containing public info contributed by the initiator.
+
+=item "ukm" (B<OSSL_KDF_PARAM_UKM>) <octet string>
+
+An alias for "partyu-info".
+In CMS this is the user keying material.
+
+=item "partyv-info" (B<OSSL_KDF_PARAM_X942_PARTYVINFO>) <octet string>
+
+An optional octet string containing public info contributed by the responder.
+
+=item "supp-pubinfo" (B<OSSL_KDF_PARAM_X942_SUPP_PUBINFO>) <octet string>
+
+An optional octet string containing some additional, mutually-known public
+information. Setting this value also sets "use-keybits" to 0.
+
+=item "use-keybits" (B<OSSL_KDF_PARAM_X942_SUPP_PRIVINFO>) <integer>
+
+The default value of 1 will use the KEK key length (in bits) as the
+"supp-pubinfo". A value of 0 disables setting the "supp-pubinfo".
+
+=item "supp-privinfo" (B<OSSL_KDF_PARAM_X942_SUPP_PRIVINFO>) <octet string>
+
+An optional octet string containing some additional, mutually-known private
+information.
+
+=item "cekalg" (B<OSSL_KDF_PARAM_CEK_ALG>) <UTF8 string>
+
+This parameter sets the CEK wrapping algorithm name.
+Valid values are "AES-128-WRAP", "AES-192-WRAP", "AES-256-WRAP" and "DES3-WRAP".
+
+=back
+
+=head1 NOTES
+
+A context for X942KDF can be obtained by calling:
+
+ EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL);
+ EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
+
+The output length of an X942KDF is specified via the I<keylen>
+parameter to the L<EVP_KDF_derive(3)> function.
+
+=head1 EXAMPLES
+
+This example derives 24 bytes, with the secret key "secret" and random user
+keying material:
+
+  EVP_KDF_CTX *kctx;
+  EVP_KDF_CTX *kctx;
+  unsigned char out[192/8];
+  unsignred char ukm[64];
+  OSSL_PARAM params[5], *p = params;
+
+  if (RAND_bytes(ukm, sizeof(ukm)) <= 0)
+      error("RAND_bytes");
+
+  kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL);
+  if (kctx == NULL)
+      error("EVP_KDF_fetch");
+  kctx = EVP_KDF_CTX_new(kdf);
+  EVP_KDF_free(kdf);
+  if (kctx == NULL)
+      error("EVP_KDF_CTX_new");
+
+  *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, "SHA256", 0);
+  *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET,
+                                           "secret", (size_t)6);
+  *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_UKM, ukm, sizeof(ukm));
+  *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CEK_ALG, "AES-256-WRAP, 0);
+  *p = OSSL_PARAM_construct_end();
+  if (EVP_KDF_CTX_set_params(kctx, params) <= 0)
+      error("EVP_KDF_CTX_set_params");
+
+  if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 0)
+      error("EVP_KDF_derive");
+
+  EVP_KDF_CTX_free(kctx);
+
+=head1 CONFORMING TO
+
+ANS1 X9.42-2003
+RFC 2631
+
+=head1 SEE ALSO
+
+L<EVP_KDF(3)>,
+L<EVP_KDF_CTX_new(3)>,
+L<EVP_KDF_CTX_free(3)>,
+L<EVP_KDF_CTX_set_params(3)>,
+L<EVP_KDF_CTX_get_kdf_size(3)>,
+L<EVP_KDF_derive(3)>,
+L<EVP_KDF(3)/PARAMETERS>
+
+=head1 HISTORY
+
+This functionality was added to OpenSSL 3.0.
+
+=head1 COPYRIGHT
+
+Copyright 2019-2020 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