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This commit is contained in:
Dr. Stephen Henson 2007-04-13 12:57:48 +00:00
parent 9cfc8a9d5c
commit 4cfb986f27
2 changed files with 97 additions and 71 deletions
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57
doc/crypto/PKCS7_encrypt.pod
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@ -18,44 +18,56 @@ B<cipher> is the symmetric cipher to use. B<flags> is an optional set of flags.
=head1 NOTES
Only RSA keys are supported in PKCS#7 and envelopedData so the recipient certificates
supplied to this function must all contain RSA public keys, though they do not have to
be signed using the RSA algorithm.
Only RSA keys are supported in PKCS#7 and envelopedData so the recipient
certificates supplied to this function must all contain RSA public keys, though
they do not have to be signed using the RSA algorithm.
EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use because
most clients will support it.
EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use
because most clients will support it.
Some old "export grade" clients may only support weak encryption using 40 or 64 bit
RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc() respectively.
Some old "export grade" clients may only support weak encryption using 40 or 64
bit RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc()
respectively.
The algorithm passed in the B<cipher> parameter must support ASN1 encoding of its
parameters.
The algorithm passed in the B<cipher> parameter must support ASN1 encoding of
its parameters.
Many browsers implement a "sign and encrypt" option which is simply an S/MIME
Many browsers implement a "sign and encrypt" option which is simply an S/MIME
envelopedData containing an S/MIME signed message. This can be readily produced
by storing the S/MIME signed message in a memory BIO and passing it to
PKCS7_encrypt().
The following flags can be passed in the B<flags> parameter.
If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended
to the data.
If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are
prepended to the data.
Normally the supplied content is translated into MIME canonical format (as required
by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation occurs. This
option should be used if the supplied data is in binary format otherwise the translation
will corrupt it. If B<PKCS7_BINARY> is set then B<PKCS7_TEXT> is ignored.
Normally the supplied content is translated into MIME canonical format (as
required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation
occurs. This option should be used if the supplied data is in binary format
otherwise the translation will corrupt it. If B<PKCS7_BINARY> is set then
B<PKCS7_TEXT> is ignored.
If the B<PKCS7_STREAM> flag is set a partial B<PKCS7> structure is output
suitable for streaming I/O: no data is read from the BIO B<in>.
=head1 NOTES
If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not>
complete and outputting its contents via a function that does not
properly finalize the B<PKCS7> structure will give unpredictable
results.
Several functions including SMIME_write_PKCS7(), d2i_PKCS7_bio_stream(),
PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization
can be performed by obtaining the streaming ASN1 B<BIO> directly using
BIO_new_PKCS7().
=head1 RETURN VALUES
PKCS7_encrypt() returns either a valid PKCS7 structure or NULL if an error occurred.
PKCS7_encrypt() returns either a PKCS7 structure or NULL if an error occurred.
The error can be obtained from ERR_get_error(3).
=head1 BUGS
The lack of single pass processing and need to hold all data in memory as
mentioned in PKCS7_sign() also applies to PKCS7_verify().
=head1 SEE ALSO
L<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_decrypt(3)|PKCS7_decrypt(3)>
@ -63,5 +75,6 @@ L<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_decrypt(3)|PKCS7_decrypt(3)>
=head1 HISTORY
PKCS7_decrypt() was added to OpenSSL 0.9.5
The B<PKCS7_STREAM> flag was first supported in OpenSSL 0.9.9.
=cut

111
doc/crypto/PKCS7_sign.pod
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@ -12,10 +12,10 @@ PKCS7_sign - create a PKCS#7 signedData structure
=head1 DESCRIPTION
PKCS7_sign() creates and returns a PKCS#7 signedData structure. B<signcert>
is the certificate to sign with, B<pkey> is the corresponsding private key.
B<certs> is an optional additional set of certificates to include in the
PKCS#7 structure (for example any intermediate CAs in the chain).
PKCS7_sign() creates and returns a PKCS#7 signedData structure. B<signcert> is
the certificate to sign with, B<pkey> is the corresponsding private key.
B<certs> is an optional additional set of certificates to include in the PKCS#7
structure (for example any intermediate CAs in the chain).
The data to be signed is read from BIO B<data>.
@ -23,72 +23,83 @@ B<flags> is an optional set of flags.
=head1 NOTES
Any of the following flags (ored together) can be passed in the B<flags> parameter.
Any of the following flags (ored together) can be passed in the B<flags>
parameter.
Many S/MIME clients expect the signed content to include valid MIME headers. If
the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended
to the data.
If B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the
PKCS7 structure, the signer's certificate must still be supplied in the B<signcert>
parameter though. This can reduce the size of the signature if the signers certificate
can be obtained by other means: for example a previously signed message.
PKCS7 structure, the signer's certificate must still be supplied in the
B<signcert> parameter though. This can reduce the size of the signature if the
signers certificate can be obtained by other means: for example a previously
signed message.
The data being signed is included in the PKCS7 structure, unless B<PKCS7_DETACHED>
is set in which case it is omitted. This is used for PKCS7 detached signatures
which are used in S/MIME plaintext signed messages for example.
The data being signed is included in the PKCS7 structure, unless
B<PKCS7_DETACHED> is set in which case it is omitted. This is used for PKCS7
detached signatures which are used in S/MIME plaintext signed messages for
example.
Normally the supplied content is translated into MIME canonical format (as required
by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation occurs. This
option should be used if the supplied data is in binary format otherwise the translation
will corrupt it.
Normally the supplied content is translated into MIME canonical format (as
required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation
occurs. This option should be used if the supplied data is in binary format
otherwise the translation will corrupt it.
The signedData structure includes several PKCS#7 autenticatedAttributes including
the signing time, the PKCS#7 content type and the supported list of ciphers in
an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no authenticatedAttributes
will be used. If B<PKCS7_NOSMIMECAP> is set then just the SMIMECapabilities are
omitted.
The signedData structure includes several PKCS#7 autenticatedAttributes
including the signing time, the PKCS#7 content type and the supported list of
ciphers in an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no
authenticatedAttributes will be used. If B<PKCS7_NOSMIMECAP> is set then just
the SMIMECapabilities are omitted.
If present the SMIMECapabilities attribute indicates support for the following
algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any
of these algorithms is disabled then it will not be included.
algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of
these algorithms is disabled then it will not be included.
If the flags B<PKCS7_STREAM> is set then the returned B<PKCS7> structure is
just initialized ready to perform the signing operation. The signing is however
B<not> performed and the data to be signed is not read from the B<data>
parameter. Signing is deferred until after the data has been written. In this
way data can be signed in a single pass.
If the B<PKCS7_PARTIAL> flag is set a partial B<PKCS7> structure is output to
which additional signers and capabilities can be added before finalization.
If the flags B<PKCS7_PARTSIGN> is set then the returned B<PKCS7> structure
is just initialized ready to perform the signing operation. The signing
is however B<not> performed and the data to be signed is not read from
the B<data> parameter. Signing is deferred until after the data has been
written. In this way data can be signed in a single pass. Currently the
flag B<PKCS7_DETACHED> B<must> also be set.
=head1 NOTES
Currently the flag B<PKCS7_PARTSIGN> is only supported for detached
data. If this flag is set the returned B<PKCS7> structure is B<not>
complete and outputting its contents via a function that does not
properly finalize the B<PKCS7> structure will give unpredictable
results.
If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not>
complete and outputting its contents via a function that does not properly
finalize the B<PKCS7> structure will give unpredictable results.
At present only the SMIME_write_PKCS7() function properly finalizes the
structure.
Several functions including SMIME_write_PKCS7(), d2i_PKCS7_bio_stream(),
PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization
can be performed by obtaining the streaming ASN1 B<BIO> directly using
BIO_new_PKCS7().
If a signer is specified it will use the default digest for the signing
algorithm. This is B<SHA1> for both RSA and DSA keys.
In OpenSSL 0.9.9 the B<certs>, B<signcert> and B<pkey> parameters can all be
B<NULL> if the B<PKCS7_PARTIAL> flag is set. One or more signers can be added
using the function B<PKCS7_sign_add_signer()>. B<PKCS7_final()> must also be
called to finalize the structure if streaming is not enabled. Alternative
signing digests can also be specified using this method.
In OpenSSL 0.9.9 if B<signcert> and B<pkey> are NULL then a certificates only
PKCS#7 structure is output.
In versions of OpenSSL before 0.9.9 the B<signcert> and B<pkey> parameters must
B<NOT> be NULL.
=head1 BUGS
PKCS7_sign() is somewhat limited. It does not support multiple signers, some
advanced attributes such as counter signatures are not supported.
The SHA1 digest algorithm is currently always used.
When the signed data is not detached it will be stored in memory within the
B<PKCS7> structure. This effectively limits the size of messages which can be
signed due to memory restraints. There should be a way to sign data without
having to hold it all in memory, this would however require fairly major
revisions of the OpenSSL ASN1 code.
Some advanced attributes such as counter signatures are not supported.
=head1 RETURN VALUES
PKCS7_sign() returns either a valid PKCS7 structure or NULL if an error occurred.
The error can be obtained from ERR_get_error(3).
PKCS7_sign() returns either a valid PKCS7 structure or NULL if an error
occurred. The error can be obtained from ERR_get_error(3).
=head1 SEE ALSO
@ -98,6 +109,8 @@ L<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_verify(3)|PKCS7_verify(3)>
PKCS7_sign() was added to OpenSSL 0.9.5
The B<PKCS7_PARTSIGN> flag was added in OpenSSL 0.9.8
The B<PKCS7_PARTIAL> flag was added in OpenSSL 0.9.9
The B<PKCS7_STREAM> flag was added in OpenSSL 0.9.9
=cut