Update docs.

[openssl.git] / doc / crypto / EVP_SignInit.pod

diff --git a/doc/crypto/EVP_SignInit.pod b/doc/crypto/EVP_SignInit.pod
index 7f9265d0a60d852e55923acaeb3d200e7e2b9b91..32e9d5480947db6439b336c19da5df2b669a2628 100644 (file)
--- a/doc/crypto/EVP_SignInit.pod
+++ b/doc/crypto/EVP_SignInit.pod
@@ -8,10 +8,12 @@ EVP_SignInit, EVP_SignUpdate, EVP_SignFinal - EVP signing functions
 
  #include <openssl/evp.h>
 
- void EVP_SignInit(EVP_MD_CTX *ctx, const EVP_MD *type);
- void EVP_SignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_SignInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
+ int EVP_SignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
  int EVP_SignFinal(EVP_MD_CTX *ctx,unsigned char *sig,unsigned int *s, EVP_PKEY *pkey);
 
+ void EVP_SignInit(EVP_MD_CTX *ctx, const EVP_MD *type);
+
  int EVP_PKEY_size(EVP_PKEY *pkey);
 
 =head1 DESCRIPTION
@@ -19,9 +21,9 @@ EVP_SignInit, EVP_SignUpdate, EVP_SignFinal - EVP signing functions
 The EVP signature routines are a high level interface to digital
 signatures.
 
-EVP_SignInit() initializes a signing context B<ctx> to using digest
-B<type>: this will typically be supplied by a function such as
-EVP_sha1().
+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.
 
 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
@@ -31,18 +33,18 @@ 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)
 will be written to the integer at B<s>, at most EVP_PKEY_size(pkey) bytes
-will be written.  After calling EVP_SignFinal() no additional calls to
-EVP_SignUpdate() can be made, but EVP_SignInit() can be called to initialize
-a new signature operation.
+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 actual
 signature returned by EVP_SignFinal() may be smaller.
 
 =head1 RETURN VALUES
 
-EVP_SignInit() and EVP_SignUpdate() do not return values.
-
-EVP_SignFinal() returns 1 for success and 0 for failure.
+EVP_SignInit_ex(), EVP_SignUpdate() and EVP_SignFinal() return 1
+for success and 0 for failure.
 
 EVP_PKEY_size() returns the maximum size of a signature in bytes.
 
@@ -63,11 +65,18 @@ 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
 seeded for RSA signatures.
 
+The call to EVP_SignFinal() internally finalizes a copy of the digest context.
+This means that calls to EVP_SignUpdate() and EVP_SignFinal() can be called
+later to digest and sign 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
 
-Several of the functions do not return values: maybe they should. Although the
-internal digest operations will never fail some future hardware based operations
-might.
+Older versions of this documentation wrongly stated that calls to 
+EVP_SignUpdate() could not be made after calling EVP_SignFinal().
 
 =head1 SEE ALSO
 
@@ -82,4 +91,6 @@ L<sha(3)|sha(3)>, L<digest(1)|digest(1)>
 EVP_SignInit(), EVP_SignUpdate() and EVP_SignFinal() are
 available in all versions of SSLeay and OpenSSL.
 
+EVP_SignInit_ex() was added in OpenSSL 0.9.7
+
 =cut