Commit c3eb0c1e authored by Geoff Thorpe's avatar Geoff Thorpe
Browse files

Various parts of the RSA documentation were inaccurate and out of date and 

this fixes those that I'm currently aware of. In particular, the ENGINE
interference in the RSA API has hopefully been clarified. This still needs
to be done for other areas of the API ...
parent d18f6813

doc/crypto/RSA_new.pod

+4 −2
Original line number Diff line number Diff line
@@ -14,7 +14,8 @@ RSA_new, RSA_free - allocate and free RSA objects 


=head1 DESCRIPTION



RSA_new() allocates and initializes an B<RSA> structure.

RSA_new() allocates and initializes an B<RSA> structure. It is equivalent to

calling RSA_new_method(NULL).



RSA_free() frees the B<RSA> structure and its components. The key is

erased before the memory is returned to the system.
@@ -29,7 +30,8 @@ RSA_free() returns no value. 


=head1 SEE ALSO



L<err(3)|err(3)>, L<rsa(3)|rsa(3)>, L<RSA_generate_key(3)|RSA_generate_key(3)>

L<err(3)|err(3)>, L<rsa(3)|rsa(3)>, L<RSA_generate_key(3)|RSA_generate_key(3)>,

L<RSA_new_method(3)|RSA_new_method(3)>



=head1 HISTORY

doc/crypto/RSA_set_method.pod

+84 −43
Original line number Diff line number Diff line
@@ -11,52 +11,64 @@ RSA_null_method, RSA_flags, RSA_new_method - select RSA method 
 #include <openssl/rsa.h>

 #include <openssl/engine.h>



 void RSA_set_default_openssl_method(RSA_METHOD *meth);

 void RSA_set_default_method(const RSA_METHOD *meth);



 RSA_METHOD *RSA_get_default_openssl_method(void);

 RSA_METHOD *RSA_get_default_method(void);



 int RSA_set_method(RSA *rsa, ENGINE *engine);

 int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);



 RSA_METHOD *RSA_get_method(RSA *rsa);

 RSA_METHOD *RSA_get_method(const RSA *rsa);



 RSA_METHOD *RSA_PKCS1_SSLeay(void);



 RSA_METHOD *RSA_null_method(void);



 int RSA_flags(RSA *rsa);

 int RSA_flags(const RSA *rsa);



 RSA *RSA_new_method(ENGINE *engine);



=head1 DESCRIPTION



An B<RSA_METHOD> specifies the functions that OpenSSL uses for RSA

operations. By modifying the method, alternative implementations

such as hardware accelerators may be used.



Initially, the default is to use the OpenSSL internal implementation.

RSA_PKCS1_SSLeay() returns a pointer to that method.



RSA_set_default_openssl_method() makes B<meth> the default method for all B<RSA>

structures created later. B<NB:> This is true only whilst the default engine

for RSA operations remains as "openssl". ENGINEs provide an

encapsulation for implementations of one or more algorithms at a time, and all

the RSA functions mentioned here operate within the scope of the default

"openssl" engine.



RSA_get_default_openssl_method() returns a pointer to the current default

method for the "openssl" engine.



RSA_set_method() selects B<engine> for all operations using the key

B<rsa>.



RSA_get_method() returns a pointer to the RSA_METHOD from the currently

selected ENGINE for B<rsa>.



RSA_flags() returns the B<flags> that are set for B<rsa>'s current method.

operations. By modifying the method, alternative implementations such as

hardware accelerators may be used. IMPORTANT: See the NOTES section for

important information about how these RSA API functions are affected by the

use of B<ENGINE> API calls.



Initially, the default RSA_METHOD is the OpenSSL internal implementation,

as returned by RSA_PKCS1_SSLeay().



RSA_set_default_method() makes B<meth> the default method for all <RSA>

structures created later. B<NB>: This is true only whilst no ENGINE has

been set as a default for RSA, so this function is no longer recommended.



RSA_get_default_method() returns a pointer to the current default

RSA_METHOD. However, the meaningfulness of this result is dependant on

whether the ENGINE API is being used, so this function is no longer 

recommended.



RSA_set_method() selects B<meth> to perform all operations using the key

B<rsa>. This will replace the RSA_METHOD used by the RSA key and if the

previous method was supplied by an ENGINE, the handle to that ENGINE will

be released during the change. It is possible to have RSA keys that only

work with certain RSA_METHOD implementations (eg. from an ENGINE module

that supports embedded hardware-protected keys), and in such cases

attempting to change the RSA_METHOD for the key can have unexpected

results.



RSA_get_method() returns a pointer to the RSA_METHOD being used by B<rsa>.

This method may or may not be supplied by an ENGINE implementation, but if

it is, the return value can only be guaranteed to be valid as long as the

RSA key itself is valid and does not have its implementation changed by

RSA_set_method().



RSA_flags() returns the B<flags> that are set for B<rsa>'s current

RSA_METHOD. See the BUGS section.



RSA_new_method() allocates and initializes an RSA structure so that

B<engine> will be used for the RSA operations. If B<engine> is NULL,

the default engine for RSA operations is used.

B<engine> will be used for the RSA operations. If B<engine> is NULL, the

default ENGINE for RSA operations is used, and if no default ENGINE is set,

the RSA_METHOD controlled by RSA_set_default_method() is used.



=head1 THE RSA_METHOD STRUCTURE
@@ -121,22 +133,45 @@ the default engine for RSA operations is used. 


=head1 RETURN VALUES



RSA_PKCS1_SSLeay(), RSA_PKCS1_null_method(), RSA_get_default_openssl_method()

RSA_PKCS1_SSLeay(), RSA_PKCS1_null_method(), RSA_get_default_method()

and RSA_get_method() return pointers to the respective RSA_METHODs.



RSA_set_default_openssl_method() returns no value.

RSA_set_default_method() returns no value.



RSA_set_method() selects B<engine> as the engine that will be responsible for

all operations using the structure B<rsa>. If this function completes successfully,

then the B<rsa> structure will have its own functional reference of B<engine>, so

the caller should remember to free their own reference to B<engine> when they are

finished with it. NB: An ENGINE's RSA_METHOD can be retrieved (or set) by

ENGINE_get_RSA() or ENGINE_set_RSA().

RSA_set_method() returns a pointer to the old RSA_METHOD implementation

that was replaced. However, this return value should probably be ignored

because if it was supplied by an ENGINE, the pointer could be invalidated

at any time if the ENGINE is unloaded (in fact it could be unloaded as a

result of the RSA_set_method() function releasing its handle to the

ENGINE). For this reason, the return type may be replaced with a B<void>

declaration in a future release.



RSA_new_method() returns NULL and sets an error code that can be

obtained by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise

RSA_new_method() returns NULL and sets an error code that can be obtained

by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise

it returns a pointer to the newly allocated structure.



=head1 NOTES



As of version 0.9.7, RSA_METHOD implementations are grouped together with

other algorithmic APIs (eg. DSA_METHOD, EVP_CIPHER, etc) into B<ENGINE>

modules. If a default ENGINE is specified for RSA functionality using an

ENGINE API function, that will override any RSA defaults set using the RSA

API (ie.  RSA_set_default_method()). For this reason, the ENGINE API is the

recommended way to control default implementations for use in RSA and other

cryptographic algorithms.



=head1 BUGS



The behaviour of RSA_flags() is a mis-feature that is left as-is for now

to avoid creating compatibility problems. RSA functionality, such as the

encryption functions, are controlled by the B<flags> value in the RSA key

itself, not by the B<flags> value in the RSA_METHOD attached to the RSA key

(which is what this function returns). If the flags element of an RSA key

is changed, the changes will be honoured by RSA functionality but will not

be reflected in the return value of the RSA_flags() function - in effect

RSA_flags() behaves more like an RSA_default_flags() function (which does

not currently exist).



=head1 SEE ALSO



L<rsa(3)|rsa(3)>, L<RSA_new(3)|RSA_new(3)>
@@ -149,8 +184,14 @@ well as the rsa_sign and rsa_verify components of RSA_METHOD were 
added in OpenSSL 0.9.4.



RSA_set_default_openssl_method() and RSA_get_default_openssl_method()

replaced RSA_set_default_method() and RSA_get_default_method() respectively,

and RSA_set_method() and RSA_new_method() were altered to use B<ENGINE>s

rather than B<RSA_METHOD>s during development of OpenSSL 0.9.6.

replaced RSA_set_default_method() and RSA_get_default_method()

respectively, and RSA_set_method() and RSA_new_method() were altered to use

B<ENGINE>s rather than B<RSA_METHOD>s during development of the engine

version of OpenSSL 0.9.6. For 0.9.7, the handling of defaults in the ENGINE

API was restructured so that this change was reversed, and behaviour of the

other functions resembled more closely the previous behaviour. The

behaviour of defaults in the ENGINE API now transparently overrides the

behaviour of defaults in the RSA API without requiring changing these

function prototypes.



=cut

doc/crypto/rsa.pod

+19 −12
Original line number Diff line number Diff line
@@ -16,13 +16,17 @@ rsa - RSA public key cryptosystem 
    unsigned char *to, RSA *rsa, int padding);

 int RSA_private_decrypt(int flen, unsigned char *from,

    unsigned char *to, RSA *rsa, int padding);

 int RSA_private_encrypt(int flen, unsigned char *from,

    unsigned char *to, RSA *rsa,int padding);

 int RSA_public_decrypt(int flen, unsigned char *from, 

    unsigned char *to, RSA *rsa,int padding);



 int RSA_sign(int type, unsigned char *m, unsigned int m_len,

    unsigned char *sigret, unsigned int *siglen, RSA *rsa);

 int RSA_verify(int type, unsigned char *m, unsigned int m_len,

    unsigned char *sigbuf, unsigned int siglen, RSA *rsa);



 int RSA_size(RSA *rsa);

 int RSA_size(const RSA *rsa);



 RSA *RSA_generate_key(int num, unsigned long e,

    void (*callback)(int,int,void *), void *cb_arg);
@@ -32,13 +36,13 @@ rsa - RSA public key cryptosystem 
 int RSA_blinding_on(RSA *rsa, BN_CTX *ctx);

 void RSA_blinding_off(RSA *rsa);



 void RSA_set_default_openssl_method(RSA_METHOD *meth);

 RSA_METHOD *RSA_get_default_openssl_method(void);

 int RSA_set_method(RSA *rsa, ENGINE *engine);

 RSA_METHOD *RSA_get_method(RSA *rsa);

 void RSA_set_default_method(const RSA_METHOD *meth);

 const RSA_METHOD *RSA_get_default_method(void);

 int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);

 const RSA_METHOD *RSA_get_method(const RSA *rsa);

 RSA_METHOD *RSA_PKCS1_SSLeay(void);

 RSA_METHOD *RSA_null_method(void);

 int RSA_flags(RSA *rsa);

 int RSA_flags(const RSA *rsa);

 RSA *RSA_new_method(ENGINE *engine);



 int RSA_print(BIO *bp, RSA *x, int offset);
@@ -49,11 +53,6 @@ rsa - RSA public key cryptosystem 
 int RSA_set_ex_data(RSA *r,int idx,char *arg);

 char *RSA_get_ex_data(RSA *r, int idx);



 int RSA_private_encrypt(int flen, unsigned char *from,

    unsigned char *to, RSA *rsa,int padding);

 int RSA_public_decrypt(int flen, unsigned char *from, 

    unsigned char *to, RSA *rsa,int padding);



 int RSA_sign_ASN1_OCTET_STRING(int dummy, unsigned char *m,

    unsigned int m_len, unsigned char *sigret, unsigned int *siglen,

    RSA *rsa);
@@ -90,6 +89,14 @@ B<p>, B<q>, B<dmp1>, B<dmq1> and B<iqmp> may be B<NULL> in private 
keys, but the RSA operations are much faster when these values are

available.



Note that RSA keys may use non-standard B<RSA_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 RSA

structure elements directly and instead use API functions to query or

modify keys.



=head1 CONFORMING TO



SSL, PKCS #1 v2.0
@@ -101,7 +108,7 @@ RSA was covered by a US patent which expired in September 2000. 
=head1 SEE ALSO



L<rsa(1)|rsa(1)>, L<bn(3)|bn(3)>, L<dsa(3)|dsa(3)>, L<dh(3)|dh(3)>,

L<rand(3)|rand(3)>, L<RSA_new(3)|RSA_new(3)>,

L<rand(3)|rand(3)>, L<engine(3)|engine(3)>, L<RSA_new(3)|RSA_new(3)>,

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

L<RSA_sign(3)|RSA_sign(3)>, L<RSA_size(3)|RSA_size(3)>,

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