Commit 0263b992 authored by Matt Caswell's avatar Matt Caswell
Browse files

Add documentation for following DH and DH_METHOD opacity 



A number of new functions have been added following the DH and DH_METHOD
opacity commits. This commit provides documentation for those functions.

Reviewed-by: default avatarRichard Levitte <levitte@openssl.org>
parent 998f2cb8

crypto/dh/dh_locl.h

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ struct dh_method { 
    /* Methods here */

    int (*generate_key) (DH *dh);

    int (*compute_key) (unsigned char *key, const BIGNUM *pub_key, DH *dh);



    /* Can be null */

    int (*bn_mod_exp) (const DH *dh, BIGNUM *r, const BIGNUM *a,

                       const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx,

doc/crypto/DH_get0_pqg.pod

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=pod



=head1 NAME



DH_get0_pqg, DH_set0_pqg, DH_get0_key, DH_set0_key, DH_clear_flags,

DH_test_flags, DH_set_flags, DH_get0_engine, DH_get_length,

DH_set_length - Routines for getting and setting data in a DH object



=head1 SYNOPSIS



 #include <openssl/dh.h>



 void DH_get0_pqg(const DH *dh, BIGNUM **p, BIGNUM **q, BIGNUM **g);

 int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g);

 void DH_get0_key(const DH *dh, BIGNUM **pub_key, BIGNUM **priv_key);

 int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);

 void DH_clear_flags(DH *dh, int flags);

 int DH_test_flags(const DH *dh, int flags);

 void DH_set_flags(DH *dh, int flags);

 ENGINE *DH_get0_engine(DH *d);

 long DH_get_length(const DH *dh);

 int DH_set_length(DH *dh, long length);



=head1 DESCRIPTION



A DH object contains the parameters B<p>, B<q> and B<g>. Note that the B<q>

parameter is optional. It also contains a public key (B<pub_key>) and

(optionally) a private key (B<priv_key>).



The B<p>, B<q> and B<g> parameters can be obtained by calling DH_get0_pqg().

If the parameters have not yet been set then B<*p>, B<*q> and B<*g> will be set

to NULL. Otherwise they are set to pointers to their respective values. These

point directly to the internal representations of the values and therefore

should not be freed directly.



The B<p>, B<q> and B<g> values can be set by calling DH_set0_pqg() and passing

the new values for B<p>, B<q> and B<g> as parameters to the function. Calling

this function transfers the memory management of the values to the DH object,

and therefore the values that have been passed in should not be freed directly

after this function has been called. The B<q> parameter may be NULL.



To get the public and private key values use the DH_get0_key() function. A

pointer to the public key will be stored in B<*pub_key>, and a pointer to the

private key will be stored in B<*priv_key>. Either may be NULL if they have not

been set yet, although if the private key has been set then the public key must

be. The values point to the internal representation of the public key and

private key values. This memory should not be freed directly.



The public and private key values can be set using DH_set0_key(). The public

key must always be non-NULL. The private key may be NULL. As for DH_set0_pqg()

this function transfers the memory management of the key values to the DH

object, and therefore they should not be freed directly after this function has

been called.



DH_set_flags() sets the flags in the B<flags> parameter on the DH object.

Multiple flags can be passed in one go (bitwise ORed together). Any flags that

are already set are left set. DH_test_flags() tests to see whether the flags

passed in the B<flags> parameter are currently set in the DH object. Multiple

flags can be tested in one go. All flags that are currently set are returned, or

zero if none of the flags are set. DH_clear_flags() clears the specified flags

within the DH object.



DH_get0_engine() returns a handle to the ENGINE that has been set for this DH

object, or NULL if no such ENGINE has been set.



The DH_get_length() and DH_set_length() functions get and set the optional

length parameter associated with this DH object. If the length is non-zero then

it is used, otherwise it is ignored. The B<length> parameter indicates the

length of the secret exponent (private key) in bits.



=head1 RETURN VALUES



DH_set0_pqg() and DH_set0_key() return 1 on success or 0 on failure.



DH_test_flags() returns the current state of the flags in the DH object.



DH_get0_engine() returns the ENGINE set for the DH object or NULL if no ENGINE

has been set.



DH_get_length() returns the length of the secret exponent (private key) in bits,

or zero if no such length has been explicitly set.



=head1 SEE ALSO



L<dh(3)>, L<DH_new(3)>, L<DH_generate_parameters(3)>, L<DH_generate_key(3)>,

L<DH_set_method(3)>, L<DH_size(3)>, L<DH_meth_new(3)>



=head1 HISTORY



The functions described here were added in OpenSSL version 1.1.0.



=cut

doc/crypto/DH_meth_new.pod

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=pod



=head1 NAME



DH_meth_new, DH_meth_free, DH_meth_dup, DH_meth_get0_name, DH_meth_set1_name,

DH_meth_get_flags, DH_meth_set_flags, DH_meth_get0_app_data,

DH_meth_set0_app_data, DH_meth_get_generate_key, DH_meth_set_generate_key,

DH_meth_get_compute_key, DH_meth_set_compute_key, DH_meth_get_bn_mod_exp,

DH_meth_set_bn_mod_exp, DH_meth_get_init, DH_meth_set_init, DH_meth_get_finish,

DH_meth_set_finish, DH_meth_get_generate_params,

DH_meth_set_generate_params - Routines to build up DH methods



=head1 SYNOPSIS



 #include <openssl/dh.h>



 DH_METHOD *DH_meth_new(const char *name, int flags);

 void DH_meth_free(DH_METHOD *dhm);

 DH_METHOD *DH_meth_dup(const DH_METHOD *dhm);

 const char *DH_meth_get0_name(const DH_METHOD *dhm);

 int DH_meth_set1_name(DH_METHOD *dhm, const char *name);

 int DH_meth_get_flags(DH_METHOD *dhm);

 int DH_meth_set_flags(DH_METHOD *dhm, int flags);

 void *DH_meth_get0_app_data(const DH_METHOD *dhm);

 int DH_meth_set0_app_data(DH_METHOD *dhm, void *app_data);

 int (*DH_meth_get_generate_key(const DH_METHOD *dhm)) (DH *);

 int DH_meth_set_generate_key(DH_METHOD *dhm, int (*generate_key) (DH *));

 int (*DH_meth_get_compute_key(const DH_METHOD *dhm))

         (unsigned char *key, const BIGNUM *pub_key, DH *dh);

 int DH_meth_set_compute_key(DH_METHOD *dhm,

         int (*compute_key) (unsigned char *key, const BIGNUM *pub_key, DH *dh));

 int (*DH_meth_get_bn_mod_exp(const DH_METHOD *dhm))

     (const DH *dh, BIGNUM *r, const BIGNUM *a, const BIGNUM *p,

      const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);

 int DH_meth_set_bn_mod_exp(DH_METHOD *dhm,

     int (*bn_mod_exp) (const DH *dh, BIGNUM *r, const BIGNUM *a,

                        const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx,

                        BN_MONT_CTX *m_ctx));

 int (*DH_meth_get_init(const DH_METHOD *dhm))(DH *);

 int DH_meth_set_init(DH_METHOD *dhm, int (*init)(DH *));

 int (*DH_meth_get_finish(const DH_METHOD *dhm)) (DH *);

 int DH_meth_set_finish(DH_METHOD *dhm, int (*finish) (DH *));

 int (*DH_meth_get_generate_params(const DH_METHOD *dhm))

         (DH *, int, int, BN_GENCB *);

 int DH_meth_set_generate_params(DH_METHOD *dhm,

         int (*generate_params) (DH *, int, int, BN_GENCB *));



=head1 DESCRIPTION



The B<DH_METHOD> type is a structure used for the provision of custom DH

implementations. It provides a set of of functions used by OpenSSL for the

implementation of the various DH capabilities. See the L<dh(3)> page for more

information.



DH_meth_new() creates a new B<DH_METHOD> structure. It should be given a

unique B<name> and a set of B<flags>. The B<name> should be a NULL terminated

string, which will be duplicated and stored in the B<DH_METHOD> object. It is

the callers responsibility to free the original string. The flags will be used

during the construction of a new B<DH> object based on this B<DH_METHOD>. Any

new B<DH> object will have those flags set by default.



DH_meth_dup() creates a duplicate copy of the B<DH_METHOD> object passed as a

parameter. This might be useful for creating a new B<DH_METHOD> based on an

existing one, but with some differences.



DH_meth_free() destroys a B<DH_METHOD> structure and frees up any memory

associated with it.



DH_meth_get0_name() will return a pointer to the name of this DH_METHOD. This

is a pointer to the internal name string and so should not be freed by the

caller. DH_meth_set1_name() sets the name of the DH_METHOD to B<name>. The

string is duplicated and the copy is stored in the DH_METHOD structure, so the

caller remains responsible for freeing the memory associated with the name.



DH_meth_get_flags() returns the current value of the flags associated with this

DH_METHOD. DH_meth_set_flags() provides the ability to set these flags.



The functions DH_meth_get0_app_data() and DH_meth_set0_app_data() provide the

ability to associate implementation specific data with the DH_METHOD. It is

the application's responsibility to free this data before the DH_METHOD is

freed via a call to DH_meth_free().



DH_meth_get_generate_key() and DH_meth_set_generate_key() get and set the

function used for generating a new DH key pair respectively. This function will

be called in response to the application calling DH_generate_key(). The

parameter for the function has the same meaning as for DH_generate_key().



DH_meth_get_compute_key() and DH_meth_set_compute_key() get and set the

function used for computing a new DH shared secret respectively. This function

will be called in response to the application calling DH_compute_key(). The

parameters for the function have the same meaning as for DH_compute_key().



DH_meth_get_bn_mod_exp() and DH_meth_set_bn_mod_exp() get and set the function

used for computing the following value:



 r = a ^ p mod m



This function will be called by the default OpenSSL function for

DH_generate_key(). The result is stored in the B<r> parameter. This function

may be NULL unless using the default generate key function, in which case it

must be present.



DH_meth_get_init() and DH_meth_set_init() get and set the function used

for creating a new DH instance respectively. This function will be

called in response to the application calling DH_new() (if the current default

DH_METHOD is this one) or DH_new_method(). The DH_new() and DH_new_method()

functions will allocate the memory for the new DH object, and a pointer to this

newly allocated structure will be passed as a parameter to the function. This

function may be NULL.



DH_meth_get_finish() and DH_meth_set_finish() get and set the function used

for destroying an instance of a DH object respectively. This function will be

called in response to the application calling DH_free(). A pointer to the DH

to be destroyed is passed as a parameter. The destroy function should be used

for DH implementation specific clean up. The memory for the DH itself should

not be freed by this function. This function may be NULL.



DH_meth_get_generate_params() and DH_meth_set_generate_params() get and set the

function used for generating DH parameters respectively. This function will be

called in response to the application calling DH_generate_parameters_ex() (or

DH_generate_parameters()). The parameters for the function have the same

meaning as for DH_generate_parameters_ex(). This function may be NULL.



=head1 RETURN VALUES



DH_meth_new() and DH_meth_dup() return the newly allocated DH_METHOD object

or NULL on failure.



DH_meth_get0_name() and DH_meth_get_flags() return the name and flags

associated with the DH_METHOD respectively.



All other DH_meth_get_*() functions return the appropriate function pointer

that has been set in the DH_METHOD, or NULL if no such pointer has yet been

set.



DH_meth_set1_name() and all DH_meth_set_*() functions return 1 on success or

0 on failure.



=head1 SEE ALSO



L<dh(3)>, L<DH_new(3)>, L<DH_generate_parameters(3)>, L<DH_generate_key(3)>,

L<DH_set_method(3)>, L<DH_size(3)>, L<DH_get0_pqg(3)>



=head1 HISTORY



The functions described here were added in OpenSSL version 1.1.0.



=cut

doc/crypto/DH_set_method.pod

+3 −30
Original line number Diff line number Diff line
@@ -52,35 +52,8 @@ be used for the DH operations. If B<engine> is NULL, the default ENGINE for DH 
operations is used, and if no default ENGINE is set, the DH_METHOD controlled by

DH_set_default_method() is used.



=head1 THE DH_METHOD STRUCTURE



 typedef struct dh_meth_st

 {

     /* name of the implementation */

	const char *name;



     /* generate private and public DH values for key agreement */

        int (*generate_key)(DH *dh);



     /* compute shared secret */

        int (*compute_key)(unsigned char *key, BIGNUM *pub_key, DH *dh);



     /* compute r = a ^ p mod m (May be NULL for some implementations) */

        int (*bn_mod_exp)(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p,

                                const BIGNUM *m, BN_CTX *ctx,

                                BN_MONT_CTX *m_ctx);



     /* called at DH_new */

        int (*init)(DH *dh);



     /* called at DH_free */

        int (*finish)(DH *dh);



        int flags;



        char *app_data; /* ?? */



 } DH_METHOD;

A new DH_METHOD object may be constructed using DH_meth_new() (see

L<DH_meth_new(3)>).



=head1 RETURN VALUES
@@ -99,6 +72,6 @@ returns a pointer to the newly allocated structure. 


=head1 SEE ALSO



L<dh(3)>, L<DH_new(3)>

L<dh(3)>, L<DH_new(3)>, L<DH_meth_new(3)>



=cut

doc/crypto/dh.pod

+5 −15
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@@ -38,25 +38,15 @@ The generation of shared DH parameters is described in 
L<DH_generate_parameters(3)>; L<DH_generate_key(3)> describes how

to perform a key agreement.



The B<DH> structure consists of several BIGNUM components.



 struct

        {

        BIGNUM *p;		// prime number (shared)

        BIGNUM *g;		// generator of Z_p (shared)

        BIGNUM *priv_key;	// private DH value x

        BIGNUM *pub_key;	// public DH value g^x

        // ...

        };

 DH

The B<DH> structure consists of several BIGNUM components. The prime B<p>, the

generate B<g>, the Private key B<priv_key> and the public key B<pub_key>.

Optionally there may also be an additional parameter B<q>.



Note that DH keys may use non-standard B<DH_METHOD> implementations,

either directly or by the use of B<ENGINE> modules. In some cases (eg. an

ENGINE providing support for hardware-embedded keys), these BIGNUM values

will not be used by the implementation or may be used for alternative data

storage. For this reason, applications should generally avoid using DH

structure elements directly and instead use API functions to query or

modify keys.

storage.



=head1 SEE ALSO
@@ -65,7 +55,7 @@ L<rand(3)>, L<rsa(3)>, L<engine(3)>, 
L<DH_set_method(3)>, L<DH_new(3)>,

L<DH_get_ex_new_index(3)>,

L<DH_generate_parameters(3)>,

L<DH_compute_key(3)>, L<d2i_DHparams(3)>,

L<DH_compute_key(3)>, L<DH_get0_pqg(3)>, L<DH_meth_new(3)>, L<d2i_DHparams(3)>,

L<RSA_print(3)> 



=cut