Provide documentation for i2d_ECPrivateKey and d2i_ECPrivateKey

Reviewed-by: Emilia Käsper <emilia@openssl.org>

Conflicts:
	doc/crypto/EC_KEY_new.pod
	doc/crypto/EC_POINT_new.pod

1 files changed, 67 insertions, 0 deletions

diff --git a/doc/crypto/d2i_ECPrivateKey.pod b/doc/crypto/d2i_ECPrivateKey.pod
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+=pod
+
+=head1 NAME
+
+i2d_ECPrivateKey, d2i_ECPrivate_key - Encode and decode functions for saving and
+reading EC_KEY structures
+
+=head1 SYNOPSIS
+
+ #include <openssl/ec.h>
+
+ EC_KEY *d2i_ECPrivateKey(EC_KEY **key, const unsigned char **in, long len);
+ int i2d_ECPrivateKey(EC_KEY *key, unsigned char **out);
+
+ unsigned int EC_KEY_get_enc_flags(const EC_KEY *key);
+ void EC_KEY_set_enc_flags(EC_KEY *eckey, unsigned int flags);
+
+=head1 DESCRIPTION
+
+The ECPrivateKey encode and decode routines encode and parse an
+B<EC_KEY> structure into a binary format (ASN.1 DER) and back again.
+
+These functions are similar to the d2i_X509() functions, and you should refer to
+that page for a detailed description (see L<d2i_X509(3)|d2i_X509(3)>).
+
+The format of the external representation of the public key written by
+i2d_ECPrivateKey (such as whether it is stored in a compressed form or not) is
+described by the point_conversion_form. See L<EC_GROUP_copy(3)|EC_GROUP_copy(3)>
+for a description of point_conversion_form.
+
+When reading a private key encoded without an associated public key (e.g. if
+EC_PKEY_NO_PUBKEY has been used - see below), then d2i_ECPrivateKey generates
+the missing public key automatically. Private keys encoded without parameters
+(e.g. if EC_PKEY_NO_PARAMETERS has been used - see below) then the key cannot be
+loaded using d2i_ECPrivateKey.
+
+The functions EC_KEY_get_enc_flags and EC_KEY_set_enc_flags get and set the
+value of the encoding flags for the B<key>. There are two encoding flags
+currently defined - EC_PKEY_NO_PARAMETERS and EC_PKEY_NO_PUBKEY.  These flags
+define the behaviour of how the  B<key> is converted into ASN1 in a call to
+i2d_ECPrivateKey. If EC_PKEY_NO_PARAMETERS is set then the public parameters for
+the curve are not encoded along with the private key. If EC_PKEY_NO_PUBKEY is
+set then the public key is not encoded along with the private key.
+
+=head1 RETURN VALUES
+
+d2i_ECPrivateKey() returns a valid B<EC_KEY> structure or B<NULL> if an error
+occurs. The error code that can be obtained by
+L<ERR_get_error(3)|ERR_get_error(3)>.
+
+i2d_ECPrivateKey() returns the number of bytes successfully encoded or a
+negative value if an error occurs. The error code can be obtained by
+L<ERR_get_error(3)|ERR_get_error(3)>.
+
+EC_KEY_get_enc_flags returns the value of the current encoding flags for the
+EC_KEY.
+
+=head1 SEE ALSO
+
+L<crypto(3)|crypto(3)>, L<ec(3)|ec(3)>, L<EC_GROUP_new(3)|EC_GROUP_new(3)>,
+L<EC_GROUP_copy(3)|EC_GROUP_copy(3)>, L<EC_POINT_new(3)|EC_POINT_new(3)>,
+L<EC_POINT_add(3)|EC_POINT_add(3)>,
+L<EC_GFp_simple_method(3)|EC_GFp_simple_method(3)>,
+L<d2i_ECPKParameters(3)|d2i_ECPKParameters(3)>,
+L<d2i_ECPrivateKey(3)|d2i_ECPrivateKey(3)>
+
+=cut