=pod

=encoding utf8

=head1 NAME

ECRS_SIG_new, ECRS_SIG_free,
i2d_ECRS_SIG, d2i_ECRS_SIG,
ECRS_do_sign, ECRS_do_verify,
ECRS_size, ECRS_sign, ECRS_verify - EC Ring Signature Algorithm

=head1 SYNOPSIS

 #include <openssl/ecrs.h>

 ECRS_SIG *ECRS_SIG_new(void);
 void ECRS_SIG_free(ECRS_SIG *sig);

 int i2d_ECRS_SIG(const ECRS_SIG *sig, unsigned char **pp);
 ECRS_SIG *d2i_ECRS_SIG(ECRS_SIG **sig, const unsigned char **pp, long len);

 ECRS_SIG *ECRS_do_sign(const EVP_MD *md,
                        const unsigned char *dgst, int dgstlen,
                        STACK_OF(EC_KEY) *pub_keys, EC_KEY *ec_key);
 int ECRS_do_verify(const EVP_MD *md, const unsigned char *dgst, int dgstlen,
                    const ECRS_SIG *sig, STACK_OF(EC_KEY) *pub_keys);

 int ECRS_size(const EC_KEY *ec_key, int n);

 int ECRS_sign(int type, const unsigned char *dgst, int dgstlen,
               unsigned char *sig, unsigned int *siglen,
               STACK_OF(EC_KEY) *pub_keys, EC_KEY *ec_key);
 int ECRS_verify(int type, const unsigned char *dgst, int dgstlen,
                 const unsigned char *sig, int siglen,
                 STACK_OF(EC_KEY) *pub_keys);

=head1 DESCRIPTION

Applications should use the higher level functions
L<EVP_DigestInit(3)> etc. instead of calling the hash
functions directly.

SM3 (ShangMi#3 Hash Algorithm) is a cryptographic hash function with a
256 bit output.

sm3() computes the SM3 message digest of the B<n>
bytes at B<d> and places it in B<md> (which must have space for
SHA_DIGEST_LENGTH == 20 bytes of output). If B<md> is NULL, the digest
is placed in a static array. Note: setting B<md> to NULL is B<not thread safe>.

The following functions may be used if the message is not completely
stored in memory:

sm3_nit() initializes a B<sm3_ctx_t> structure.

sm3_update() can be called repeatedly with chunks of the message to
be hashed (B<len> bytes at B<data>).

sm3_final() places the message digest in B<md>, which must have space
for SM3_DIGEST_LENGTH == 32 bytes of output, and erases the B<sm3_ctx_t>.

=head1 RETURN VALUES

sm3_init(), sm3_update(), sm3_final(), sm3_compress() and sm3() return void.

=head1 CONFORMING TO

GM/T 0004-2012 SM3 Cryptogrpahic Hash Algorithm.

=head1 SEE ALSO

L<EVP_DigestInit(3)>

=head1 COPYRIGHT

Copyright 2014-2019 The GmSSL Project. All Rights Reserved.

Licensed under the GmSSL license (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<http://gmssl.org/license.html>.

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