=head1 NAME
-EVP_SignInit, EVP_SignUpdate, EVP_SignFinal - EVP signing functions
+EVP_SignInit, EVP_SignInit_ex, EVP_SignUpdate, EVP_SignFinal - EVP signing
+functions
=head1 SYNOPSIS
signatures.
EVP_SignInit_ex() sets up signing context B<ctx> to use digest
-B<type> from ENGINE B<impl>. B<ctx> must be initialized with
-EVP_MD_CTX_init() before calling this function.
+B<type> from ENGINE B<impl>. B<ctx> must be created with
+EVP_MD_CTX_new() before calling this function.
EVP_SignUpdate() hashes B<cnt> bytes of data at B<d> into the
signature context B<ctx>. This function can be called several times on the
same B<ctx> to include additional data.
-EVP_SignFinal() signs the data in B<ctx> using the private key B<pkey>
-and places the signature in B<sig>. If the B<s> parameter is not NULL
-then the number of bytes of data written (i.e. the length of the signature)
+EVP_SignFinal() signs the data in B<ctx> using the private key B<pkey> and
+places the signature in B<sig>. B<sig> must be at least EVP_PKEY_size(pkey)
+bytes in size. B<s> is an OUT parameter, and not used as an IN parameter.
+The number of bytes of data written (i.e. the length of the signature)
will be written to the integer at B<s>, at most EVP_PKEY_size(pkey) bytes
-will be written.
+will be written.
EVP_SignInit() initializes a signing context B<ctx> to use the default
implementation of digest B<type>.
EVP_PKEY_size() returns the maximum size of a signature in bytes.
-The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
+The error codes can be obtained by L<ERR_get_error(3)>.
=head1 NOTES
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)|EVP_DigestInit(3)>.
+L<EVP_DigestInit(3)>.
When signing with DSA private keys the random number generator must be seeded
or the operation will fail. The random number generator does not need to be
Older versions of this documentation wrongly stated that calls to
EVP_SignUpdate() could not be made after calling EVP_SignFinal().
-=head1 SEE ALSO
+Since the private 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().
-L<EVP_VerifyInit(3)|EVP_VerifyInit(3)>,
-L<EVP_DigestInit(3)|EVP_DigestInit(3)>, L<err(3)|err(3)>,
-L<evp(3)|evp(3)>, L<hmac(3)|hmac(3)>, L<md2(3)|md2(3)>,
-L<md5(3)|md5(3)>, L<mdc2(3)|mdc2(3)>, L<ripemd(3)|ripemd(3)>,
-L<sha(3)|sha(3)>, L<dgst(1)|dgst(1)>
+It is not possible to change the signing parameters using these function.
-=head1 HISTORY
+The previous two bugs are fixed in the newer EVP_SignDigest*() function.
-EVP_SignInit(), EVP_SignUpdate() and EVP_SignFinal() are
-available in all versions of SSLeay and OpenSSL.
+=head1 SEE ALSO
-EVP_SignInit_ex() was added in OpenSSL 0.9.7
+L<EVP_VerifyInit(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