Commit 716854d7 authored by Richard Levitte's avatar Richard Levitte
Browse files

Document the HMAC changes 



Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
parent 25191fff

doc/crypto/hmac.pod

+24 −13
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 


=head1 NAME



HMAC, HMAC_CTX_init, HMAC_Init, HMAC_Init_ex, HMAC_Update, HMAC_Final, HMAC_CTX_cleanup - HMAC message authentication code

HMAC, HMAC_CTX_new, HMAC_CTX_reset, HMAC_CTX_free, HMAC_Init, HMAC_Init_ex, HMAC_Update, HMAC_Final - HMAC message authentication code



=head1 SYNOPSIS
@@ -12,7 +12,8 @@ HMAC, HMAC_CTX_init, HMAC_Init, HMAC_Init_ex, HMAC_Update, HMAC_Final, HMAC_CTX_ 
               int key_len, const unsigned char *d, int n,

               unsigned char *md, unsigned int *md_len);



 int HMAC_CTX_init(HMAC_CTX *ctx);

 HMAC_CTX *HMAC_CTX_new(void);

 int HMAC_CTX_reset(HMAC_CTX *ctx);



 int HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,

               const EVP_MD *md);
@@ -21,7 +22,7 @@ HMAC, HMAC_CTX_init, HMAC_Init, HMAC_Init_ex, HMAC_Update, HMAC_Final, HMAC_CTX_ 
 int HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, int len);

 int HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len);



 void HMAC_CTX_cleanup(HMAC_CTX *ctx);

 void HMAC_CTX_free(HMAC_CTX *ctx);



=head1 DESCRIPTION
@@ -40,12 +41,15 @@ the output is placed in B<md_len>, unless it is B<NULL>. 


B<evp_md> can be EVP_sha1(), EVP_ripemd160() etc.



HMAC_CTX_init() initialises a B<HMAC_CTX> before first use. It must be

called.

HMAC_CTX_new() creates a new HMAC_CTX in heap memory.



HMAC_CTX_cleanup() erases the key and other data from the B<HMAC_CTX>

and releases any associated resources. It must be called when an

B<HMAC_CTX> is no longer required.

HMAC_CTX_reset() zeroes an existing B<HMAC_CTX> and associated

resources, making it suitable for new computations as if it was newly

created with HMAC_CTX_new().



HMAC_CTX_free() erases the key and other data from the B<HMAC_CTX>,

releases any associated resources and finally frees the B<HMAC_CTX>

itself.



The following functions may be used if the message is not completely

stored in memory:
@@ -57,8 +61,8 @@ with OpenSSL 0.9.6b. 


HMAC_Init_ex() initializes or reuses a B<HMAC_CTX> structure to use

the function B<evp_md> and key B<key>. Either can be NULL, in which

case the existing one will be reused. HMAC_CTX_init() must have been

called before the first use of an B<HMAC_CTX> in this

case the existing one will be reused. B<ctx> must have been created

with HMAC_CTX_new() before the first use of an B<HMAC_CTX> in this

function. B<N.B. HMAC_Init() had this undocumented behaviour in

previous versions of OpenSSL - failure to switch to HMAC_Init_ex() in

programs that expect it will cause them to stop working>.
@@ -74,10 +78,13 @@ must have space for the hash function output. 
HMAC() returns a pointer to the message authentication code or NULL if

an error occurred.



HMAC_CTX_init(), HMAC_Init_ex(), HMAC_Update() and HMAC_Final() return 1

HMAC_CTX_new() returns a pointer to a new B<HMAC_CTX> on success or

B<NULL> if an error occurred.



HMAC_CTX_reset(), HMAC_Init_ex(), HMAC_Update() and HMAC_Final() return 1

for success or 0 if an error occurred.



HMAC_CTX_cleanup() do not return values.

HMAC_CTX_free() do not return values.



=head1 CONFORMING TO
@@ -89,7 +96,11 @@ L<sha(3)>, L<evp(3)> 


=head1 HISTORY



HMAC_CTX_init() did not return a value in OpenSSL versions before 1.1.

HMAC_CTX_init() was replaced with HMAC_CTX_reset() in OpenSSL versions 1.1.



HMAC_CTX_cleanup() existed in OpenSSL versions before 1.1.



HMAC_CTX_new() and HMAC_CTX_free() are new in OpenSSL version 1.1.



HMAC_Init_ex(), HMAC_Update() and HMAC_Final() did not return values in

versions of OpenSSL before 1.0.0.