Public key comparison and printing routine functions.

[openssl.git] / doc / crypto / EVP_PKEY_cmp.pod

diff --git a/doc/crypto/EVP_PKEY_cmp.pod b/doc/crypto/EVP_PKEY_cmp.pod
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+=pod
+
+=head1 NAME
+
+EVP_PKEY_copy_parameters, EVP_PKEY_missing_parameters, EVP_PKEY_cmp_parameters, EVP_PKEY_cmp - public key parameter and comparison functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ int EVP_PKEY_missing_parameters(const EVP_PKEY *pkey);
+ int EVP_PKEY_copy_parameters(EVP_PKEY *to, const EVP_PKEY *from);
+
+ int EVP_PKEY_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b);
+ int EVP_PKEY_cmp(const EVP_PKEY *a, const EVP_PKEY *b);
+
+=head1 DESCRIPTION
+
+The function EVP_PKEY_missing_parameters() returns 1 if the public key
+parameters of B<pkey> are missing and 0 if they are present or the algorithm
+doesn't use parameters.
+
+The function EVP_PKEY_copy_parameters() copies the parameters from key
+B<from> to key B<to>.
+
+The funcion EVP_PKEY_cmp_parameters() compares the parameters of keys
+B<a> and B<b>.
+
+The funcion EVP_PKEY_cmp() compares the public key components and paramters
+(if present) of keys B<a> and B<b>.
+
+=head1 NOTES
+
+The main purpose of the functions EVP_PKEY_missing_parameters() and
+EVP_PKEY_copy_parameters() is to handle public keys in certificates where the
+parameters are sometimes omitted from a public key if they are inherited from
+the CA that signed it.
+
+Since OpenSSL private keys contain public key components too the function
+EVP_PKEY_cmp() can also be used to determine if a private key matches
+a public key.
+
+=head1 RETURN VALUES
+
+The function EVP_PKEY_missing_parameters() returns 1 if the public key
+parameters of B<pkey> are missing and 0 if they are present or the algorithm
+doesn't use parameters.
+
+These functions EVP_PKEY_copy_parameters() returns 1 for success and 0 for
+failure.
+
+The function EVP_PKEY_cmp_parameters() and EVP_PKEY_cmp() return 1 if the
+keys match, 0 if they don't match, -1 if the key types are different and
+-2 if the operation is not supported.
+
+=head1 SEE ALSO
+
+L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,
+L<EVP_PKEY_keygen(3)|EVP_PKEY_keygen(3)> 
+
+=cut