EVP_DigestSignInit() sets up signing context B<ctx> to use digest B<type> from
ENGINE B<e> and private key B<pkey>. B<ctx> must be created with
-EVP_MD_CTX_new() before calling this function. If B<pctx> is not NULL the
+EVP_MD_CTX_new() before calling this function. If B<pctx> is not NULL, the
EVP_PKEY_CTX of the signing operation will be written to B<*pctx>: this can
-be used to set alternative signing options. The digest B<type> may be NULL if
-the signing algorithm supports it.
+be used to set alternative signing options. Note that any existing value in
+B<*pctx> is overwritten. The EVP_PKEY_CTX value returned must not be freed
+directly by the application if B<ctx> is not assigned an EVP_PKEY_CTX value before
+being passed to EVP_DigestSignInit() (which means the EVP_PKEY_CTX is created
+inside EVP_DigestSignInit() and it will be freed automatically when the
+EVP_MD_CTX is freed).
+
+The digest B<type> may be NULL if the signing algorithm supports it.
+
+No B<EVP_PKEY_CTX> will be created by EVP_DigsetSignInit() if the passed B<ctx>
+has already been assigned one via L<EVP_MD_CTX_set_ctx(3)>. See also L<SM2(7)>.
Only EVP_PKEY types that support signing can be used with these functions. This
includes MAC algorithms where the MAC generation is considered as a form of
-"signing." Built-in EVP_PKEY types supported by these functions are CMAC,
+"signing". Built-in EVP_PKEY types supported by these functions are CMAC,
Poly1305, DSA, ECDSA, HMAC, RSA, SipHash, Ed25519 and Ed448.
Not all digests can be used for all key types. The following combinations apply.
same B<ctx> to include additional data. This function is currently implemented
using a macro.
-EVP_DigestSignFinal() signs the data in B<ctx> places the signature in B<sig>.
+EVP_DigestSignFinal() signs the data in B<ctx> and places the signature in B<sig>.
If B<sig> is B<NULL> then the maximum size of the output buffer is written to
the B<siglen> parameter. If B<sig> is not B<NULL> then before the call the
-B<siglen> parameter should contain the length of the B<sig> buffer, if the
+B<siglen> parameter should contain the length of the B<sig> buffer. If the
call is successful the signature is written to B<sig> and the amount of data
written to B<siglen>.
EVP_DigestSignInit(), EVP_DigestSignUpdate(), EVP_DigestSignaFinal() and
EVP_DigestSign() return 1 for success and 0 or a negative value for failure. In
-particular a return value of -2 indicates the operation is not supported by the
+particular, a return value of -2 indicates the operation is not supported by the
public key algorithm.
The error codes can be obtained from L<ERR_get_error(3)>.
context. This means that calls to EVP_DigestSignUpdate() and
EVP_DigestSignFinal() can be called later to digest and sign additional data.
-Since only a copy of the digest context is ever finalized the context must
+Since only a copy of the digest context is ever finalized, the context must
be cleaned up after use by calling EVP_MD_CTX_free() or a memory leak
will occur.
=head1 HISTORY
EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal()
-were first added to OpenSSL 1.0.0.
+were added in OpenSSL 1.0.0.
=head1 COPYRIGHT
Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
-Licensed under the OpenSSL license (the "License"). You may not use
+Licensed under the Apache License 2.0 (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<https://www.openssl.org/source/license.html>.
projects / openssl.git / blobdiff