Public key comparison and printing routine functions.

=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)> 

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=pod

=head1 NAME

EVP_PKEY_print_public, EVP_PKEY_print_private, EVP_PKEY_print_params - public key algorithm printing routines.

=head1 SYNOPSIS

 #include <openssl/evp.h>

 int EVP_PKEY_print_public(BIO *out, const EVP_PKEY *pkey,

				int indent, ASN1_PCTX *pctx);

 int EVP_PKEY_print_private(BIO *out, const EVP_PKEY *pkey,

				int indent, ASN1_PCTX *pctx);

 int EVP_PKEY_print_params(BIO *out, const EVP_PKEY *pkey,

				int indent, ASN1_PCTX *pctx);

=head1 DESCRIPTION

The functions EVP_PKEY_print_public(), EVP_PKEY_print_private() and

EVP_PKEY_print_params() print out the public, private or parameter components

of key B<pkey> respectively. The key is sent to BIO B<out> in human readable

form. The parameter B<indent> indicated how far the printout should be indented.

The B<pctx> parameter allows the print output to be finely tuned by using

ASN1 printing options. If B<pctx> is set to NULL then default values will

be used.

=head1 NOTES

Currently no public key algorithms include any options in the B<pctx> parameter 

parameter.

If the key does not include all the components indicated by the function then

only those contained in the key will be printed. For example passing a public

key to EVP_PKEY_print_private() will only print the public components.

=head1 RETURN VALUES

These functions all return 1 for success and 0 or a negative value for failure.

In particular a return value of -2 indicates the operation is not supported by

the public key algorithm.

=head1 SEE ALSO

L<EVP_PKEY_CTX_new(3)|EVP_PKEY_CTX_new(3)>,

L<EVP_PKEY_keygen(3)|EVP_PKEY_keygen(3)> 

=head1 HISTORY

These functions were first added to OpenSSL 0.9.9.

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