mirror of
https://github.com/openssl/openssl.git
synced 2024-12-21 06:09:35 +08:00
89 lines
2.9 KiB
Plaintext
89 lines
2.9 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal - EVP signature verification functions
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/evp.h>
|
|
|
|
int EVP_VerifyInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
|
|
int EVP_VerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
|
|
int EVP_VerifyFinal(EVP_MD_CTX *ctx,unsigned char *sigbuf, unsigned int siglen,EVP_PKEY *pkey);
|
|
|
|
int EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The EVP signature verification routines are a high level interface to digital
|
|
signatures.
|
|
|
|
EVP_VerifyInit_ex() sets up verification context B<ctx> to use digest
|
|
B<type> from ENGINE B<impl>. B<ctx> must be created by calling
|
|
EVP_MD_CTX_new() before calling this function.
|
|
|
|
EVP_VerifyUpdate() hashes B<cnt> bytes of data at B<d> into the
|
|
verification context B<ctx>. This function can be called several times on the
|
|
same B<ctx> to include additional data.
|
|
|
|
EVP_VerifyFinal() verifies the data in B<ctx> using the public key B<pkey>
|
|
and against the B<siglen> bytes at B<sigbuf>.
|
|
|
|
EVP_VerifyInit() initializes verification context B<ctx> to use the default
|
|
implementation of digest B<type>.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
EVP_VerifyInit_ex() and EVP_VerifyUpdate() return 1 for success and 0 for
|
|
failure.
|
|
|
|
EVP_VerifyFinal() returns 1 for a correct signature, 0 for failure and -1 if some
|
|
other error occurred.
|
|
|
|
The error codes can be obtained by L<ERR_get_error(3)>.
|
|
|
|
=head1 NOTES
|
|
|
|
The B<EVP> interface to digital signatures should almost always be used in
|
|
preference to the low level interfaces. This is because the code then becomes
|
|
transparent to the algorithm used and much more flexible.
|
|
|
|
Due to the link between message digests and public key algorithms the correct
|
|
digest algorithm must be used with the correct public key type. A list of
|
|
algorithms and associated public key algorithms appears in
|
|
L<EVP_DigestInit(3)>.
|
|
|
|
The call to EVP_VerifyFinal() internally finalizes a copy of the digest context.
|
|
This means that calls to EVP_VerifyUpdate() and EVP_VerifyFinal() can be called
|
|
later to digest and verify additional data.
|
|
|
|
Since only a copy of the digest context is ever finalized the context must
|
|
be cleaned up after use by calling EVP_MD_CTX_cleanup() or a memory leak
|
|
will occur.
|
|
|
|
=head1 BUGS
|
|
|
|
Older versions of this documentation wrongly stated that calls to
|
|
EVP_VerifyUpdate() could not be made after calling EVP_VerifyFinal().
|
|
|
|
Since the public key is passed in the call to EVP_SignFinal() any error
|
|
relating to the private key (for example an unsuitable key and digest
|
|
combination) will not be indicated until after potentially large amounts of
|
|
data have been passed through EVP_SignUpdate().
|
|
|
|
It is not possible to change the signing parameters using these function.
|
|
|
|
The previous two bugs are fixed in the newer EVP_VerifyDigest*() function.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<evp(3)>,
|
|
L<EVP_SignInit(3)>,
|
|
L<EVP_DigestInit(3)>, L<err(3)>,
|
|
L<evp(3)>, L<hmac(3)>, L<md2(3)>,
|
|
L<md5(3)>, L<mdc2(3)>, L<ripemd(3)>,
|
|
L<sha(3)>, L<dgst(1)>
|
|
|
|
=cut
|