Add EVP_CIPHER_do_all_ex() and EVP_MD_do_all_ex()

[openssl.git] / doc / man3 / EVP_DigestSignInit.pod

diff --git a/doc/man3/EVP_DigestSignInit.pod b/doc/man3/EVP_DigestSignInit.pod
index 400e89d5f5617d3864f684859cd6d45c2644601d..0f9c95230369861827e60459e9e7c26d2adc9504 100644 (file)
--- a/doc/man3/EVP_DigestSignInit.pod
+++ b/doc/man3/EVP_DigestSignInit.pod
@@ -24,14 +24,23 @@ The EVP signature routines are a high level interface to digital signatures.
 
 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_DigestSignInit() 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.
@@ -80,10 +89,10 @@ signature context B<ctx>. This function can be called several times on the
 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>.
 
@@ -95,7 +104,7 @@ EVP_DigestSignFinal().
 
 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)>.
@@ -116,14 +125,15 @@ and public key algorithms. This meant that "clone" digests such as EVP_dss1()
 needed to be used to sign using SHA1 and DSA. This is no longer necessary and
 the use of clone digest is now discouraged.
 
-For some key types and parameters the random number generator must be seeded
-or the operation will fail.
+For some key types and parameters the random number generator must be seeded.
+If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
+external circumstances (see L<RAND(7)>), the operation will fail.
 
 The call to EVP_DigestSignFinal() internally finalizes a copy of the digest
 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.
 
@@ -138,18 +148,19 @@ L<EVP_DigestVerifyInit(3)>,
 L<EVP_DigestInit(3)>,
 L<evp(7)>, L<HMAC(3)>, L<MD2(3)>,
 L<MD5(3)>, L<MDC2(3)>, L<RIPEMD160(3)>,
-L<SHA1(3)>, L<dgst(1)>
+L<SHA1(3)>, L<dgst(1)>,
+L<RAND(7)>
 
 =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>.