1=pod 2 3=head1 NAME 4 5EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal - EVP signature verification functions 6 7=head1 SYNOPSIS 8 9 #include <openssl/evp.h> 10 11 int EVP_VerifyInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl); 12 int EVP_VerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt); 13 int EVP_VerifyFinal(EVP_MD_CTX *ctx,unsigned char *sigbuf, unsigned int siglen,EVP_PKEY *pkey); 14 15 int EVP_VerifyInit(EVP_MD_CTX *ctx, const EVP_MD *type); 16 17=head1 DESCRIPTION 18 19The EVP signature verification routines are a high level interface to digital 20signatures. 21 22EVP_VerifyInit_ex() sets up verification context B<ctx> to use digest 23B<type> from ENGINE B<impl>. B<ctx> must be initialized by calling 24EVP_MD_CTX_init() before calling this function. 25 26EVP_VerifyUpdate() hashes B<cnt> bytes of data at B<d> into the 27verification context B<ctx>. This function can be called several times on the 28same B<ctx> to include additional data. 29 30EVP_VerifyFinal() verifies the data in B<ctx> using the public key B<pkey> 31and against the B<siglen> bytes at B<sigbuf>. 32 33EVP_VerifyInit() initializes verification context B<ctx> to use the default 34implementation of digest B<type>. 35 36=head1 RETURN VALUES 37 38EVP_VerifyInit_ex() and EVP_VerifyUpdate() return 1 for success and 0 for 39failure. 40 41EVP_VerifyFinal() returns 1 for a correct signature, 0 for failure and -1 if some 42other error occurred. 43 44The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. 45 46=head1 NOTES 47 48The B<EVP> interface to digital signatures should almost always be used in 49preference to the low level interfaces. This is because the code then becomes 50transparent to the algorithm used and much more flexible. 51 52Due to the link between message digests and public key algorithms the correct 53digest algorithm must be used with the correct public key type. A list of 54algorithms and associated public key algorithms appears in 55L<EVP_DigestInit(3)|EVP_DigestInit(3)>. 56 57The call to EVP_VerifyFinal() internally finalizes a copy of the digest context. 58This means that calls to EVP_VerifyUpdate() and EVP_VerifyFinal() can be called 59later to digest and verify additional data. 60 61Since only a copy of the digest context is ever finalized the context must 62be cleaned up after use by calling EVP_MD_CTX_cleanup() or a memory leak 63will occur. 64 65=head1 BUGS 66 67Older versions of this documentation wrongly stated that calls to 68EVP_VerifyUpdate() could not be made after calling EVP_VerifyFinal(). 69 70=head1 SEE ALSO 71 72L<evp(3)|evp(3)>, 73L<EVP_SignInit(3)|EVP_SignInit(3)>, 74L<EVP_DigestInit(3)|EVP_DigestInit(3)>, L<err(3)|err(3)>, 75L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>, 76L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>, 77L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)> 78 79=head1 HISTORY 80 81EVP_VerifyInit(), EVP_VerifyUpdate() and EVP_VerifyFinal() are 82available in all versions of SSLeay and OpenSSL. 83 84EVP_VerifyInit_ex() was added in OpenSSL 0.9.7 85 86=cut 87