New docs for EVP_Digest{Sign,Verify}*() function. Update existing docs.

6 files changed, 198 insertions, 5 deletions

diff --git a/doc/crypto/BIO_f_md.pod b/doc/crypto/BIO_f_md.pod
index 0d24083e6d..e49b652a78 100644
--- a/doc/crypto/BIO_f_md.pod
+++ b/doc/crypto/BIO_f_md.pod
@@ -58,6 +58,12 @@ If an application needs to call BIO_gets() or BIO_puts() through
 a chain containing digest BIOs then this can be done by prepending
 a buffering BIO.
 
+Before OpenSSL 0.9.9 the call to BIO_get_md_ctx() would only work if the BIO
+had been initialized for example by calling BIO_set_md() ). In OpenSSL
+0.9.9 and later the context is always returned and the BIO is state is set
+to initialized. This allows applications to initialize the context externally
+if the standard calls such as BIO_set_md() are not sufficiently flexible.
+
 =head1 RETURN VALUES
 
 BIO_f_md() returns the digest BIO method.
diff --git a/doc/crypto/EVP_DigestSignInit.pod b/doc/crypto/EVP_DigestSignInit.pod
new file mode 100644
index 0000000000..b8a39191e6
--- /dev/null
+++ b/doc/crypto/EVP_DigestSignInit.pod
@@ -0,0 +1,87 @@
+=pod
+
+=head1 NAME
+
+EVP_DigestSignInit, EVP_DigestSignUpdate, EVP_DigestSignFinal - EVP signing functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ int EVP_DigestSignInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
+			const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
+ int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_DigestSignFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t *siglen);
+
+=head1 DESCRIPTION
+
+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<impl> and private key B<pkey>. B<ctx> must be initialized with
+EVP_MD_CTX_init() 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.
+
+EVP_DigestSignUpdate() 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. This function is currently implemented
+usig a macro.
+
+EVP_DigestSignFinal() signs the data in B<ctx> 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
+call is successful the signature is written to B<sig> and the amount of data
+written to B<siglen>.
+
+=head1 RETURN VALUES
+
+EVP_DigestSignInit() EVP_DigestSignUpdate() and EVP_DigestSignaFinal() 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 public key
+algorithm.
+
+The error codes can be obtained from L<ERR_get_error(3)|ERR_get_error(3)>.
+
+=head1 NOTES
+
+The B<EVP> interface to digital signatures should almost always be used in
+preference to the low level interfaces. This is because the code then becomes
+transparent to the algorithm used and much more flexible.
+
+In previous versions of OpenSSL there was a link between message digest types
+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. 
+
+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
+be cleaned up after use by calling EVP_MD_CTX_cleanup() or a memory leak
+will occur.
+
+The use of EVP_PKEY_size() with these functions is discouraged because some
+signature operations may have a signature length which depends on the
+parameters set. As a result EVP_PKEY_size() would have to return a value
+which indicates the maximum possible signature for any set of parameters.
+
+=head1 SEE ALSO
+
+L<EVP_DigestVerifyInit(3)|EVP_DigestVerifyInit(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)>
+
+=head1 HISTORY
+
+EVP_DigestSignInit(), EVP_DigestSignUpdate() and EVP_DigestSignFinal() 
+were first added to OpenSSL 0.9.9.
+
+=cut
diff --git a/doc/crypto/EVP_DigestVerifyInit.pod b/doc/crypto/EVP_DigestVerifyInit.pod
new file mode 100644
index 0000000000..56b83b2df2
--- /dev/null
+++ b/doc/crypto/EVP_DigestVerifyInit.pod
@@ -0,0 +1,82 @@
+=pod
+
+=head1 NAME
+
+EVP_DigestVerifyInit, EVP_DigestVerifyUpdate, EVP_DigestVerifyFinal - EVP signature verification functions
+
+=head1 SYNOPSIS
+
+ #include <openssl/evp.h>
+
+ int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
+			const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
+ int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t siglen);
+
+=head1 DESCRIPTION
+
+The EVP signature routines are a high level interface to digital signatures.
+
+EVP_DigestVerifyInit() sets up verification context B<ctx> to use digest
+B<type> from ENGINE B<impl> and public key B<pkey>. B<ctx> must be initialized
+with EVP_MD_CTX_init() before calling this function. If B<pctx> is not NULL the
+EVP_PKEY_CTX of the verification operation will be written to B<*pctx>: this
+can be used to set alternative verification options.
+
+EVP_DigestVerifyUpdate() hashes B<cnt> bytes of data at B<d> into the
+verification 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_DigestVerifyFinal() verifies the data in B<ctx> against the signature in
+B<sig> of length B<siglen>.
+
+=head1 RETURN VALUES
+
+EVP_DigestVerifyInit() and EVP_DigestVerifyUpdate() 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 public key algorithm.
+
+Unlike other functions the return value 0 from EVP_DigestVerifyFinal() only
+indicates that the signature did not not verify successfully (that is tbs did
+not match the original data or the signature was of invalid form) it is not an
+indication of a more serious error.
+
+The error codes can be obtained from L<ERR_get_error(3)|ERR_get_error(3)>.
+
+=head1 NOTES
+
+The B<EVP> interface to digital signatures should almost always be used in
+preference to the low level interfaces. This is because the code then becomes
+transparent to the algorithm used and much more flexible.
+
+In previous versions of OpenSSL there was a link between message digest types
+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. 
+
+The call to EVP_DigestVerifyFinal() internally finalizes a copy of the digest
+context. This means that calls to EVP_VerifyUpdate() and EVP_VerifyFinal() can
+be called later to digest and verify 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 SEE ALSO
+
+L<EVP_DigestSignInit(3)|EVP_DigestSignInit(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)>
+
+=head1 HISTORY
+
+EVP_DigestVerifyInit(), EVP_DigestVerifyUpdate() and EVP_DigestVerifyFinal() 
+were first added to OpenSSL 0.9.9.
+
+=cut
diff --git a/doc/crypto/EVP_PKEY_verify.pod b/doc/crypto/EVP_PKEY_verify.pod
index 782de101ef..d34ae8b364 100644
--- a/doc/crypto/EVP_PKEY_verify.pod
+++ b/doc/crypto/EVP_PKEY_verify.pod
@@ -34,11 +34,11 @@ context if several operations are performed using the same parameters.
 
 =head1 RETURN VALUES
 
-EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification
-was successful and 0 if it failed. Unlike other functions the return value
-0 only indicates that the signature did not not verify successfully (that is
-tbs did not match the original data or the signature was of invalid form)
-it is not an indication of a more serious error.
+EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was
+successful and 0 if it failed. Unlike other functions the return value 0 from
+EVP_PKEY_verify() only indicates that the signature did not not verify
+successfully (that is tbs did not match the original data or the signature was
+of invalid form) it is not an indication of a more serious error.
 
 A negative value indicates an error other that signature verification failure.
 In particular a return value of -2 indicates the operation is not supported by
diff --git a/doc/crypto/EVP_SignInit.pod b/doc/crypto/EVP_SignInit.pod
index b6e62ce7f6..620a623ab6 100644
--- a/doc/crypto/EVP_SignInit.pod
+++ b/doc/crypto/EVP_SignInit.pod
@@ -77,6 +77,15 @@ will occur.
 Older versions of this documentation wrongly stated that calls to 
 EVP_SignUpdate() could not be made after calling EVP_SignFinal().
 
+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().
+
+It is not possible to change the signing parameters using these function.
+
+The previous two bugs are fixed in the newer EVP_SignDigest*() function.
+
 =head1 SEE ALSO
 
 L<EVP_VerifyInit(3)|EVP_VerifyInit(3)>,
diff --git a/doc/crypto/EVP_VerifyInit.pod b/doc/crypto/EVP_VerifyInit.pod
index b6afaedee5..9097f09410 100644
--- a/doc/crypto/EVP_VerifyInit.pod
+++ b/doc/crypto/EVP_VerifyInit.pod
@@ -67,6 +67,15 @@ will occur.
 Older versions of this documentation wrongly stated that calls to 
 EVP_VerifyUpdate() could not be made after calling EVP_VerifyFinal().
 
+Since the public 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().
+
+It is not possible to change the signing parameters using these function.
+
+The previous two bugs are fixed in the newer EVP_VerifyDigest*() function.
+
 =head1 SEE ALSO
 
 L<evp(3)|evp(3)>,