1109998Smarkm=pod 2109998Smarkm 3109998Smarkm=head1 NAME 4109998Smarkm 5109998SmarkmPKCS7_sign - create a PKCS#7 signedData structure 6109998Smarkm 7109998Smarkm=head1 SYNOPSIS 8109998Smarkm 9215697Ssimon #include <openssl/pkcs7.h> 10109998Smarkm 11215697Ssimon PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs, BIO *data, int flags); 12215697Ssimon 13109998Smarkm=head1 DESCRIPTION 14109998Smarkm 15238405SjkimPKCS7_sign() creates and returns a PKCS#7 signedData structure. B<signcert> is 16238405Sjkimthe certificate to sign with, B<pkey> is the corresponsding private key. 17238405SjkimB<certs> is an optional additional set of certificates to include in the PKCS#7 18238405Sjkimstructure (for example any intermediate CAs in the chain). 19109998Smarkm 20109998SmarkmThe data to be signed is read from BIO B<data>. 21109998Smarkm 22109998SmarkmB<flags> is an optional set of flags. 23109998Smarkm 24109998Smarkm=head1 NOTES 25109998Smarkm 26238405SjkimAny of the following flags (ored together) can be passed in the B<flags> 27238405Sjkimparameter. 28109998Smarkm 29109998SmarkmMany S/MIME clients expect the signed content to include valid MIME headers. If 30109998Smarkmthe B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended 31109998Smarkmto the data. 32109998Smarkm 33109998SmarkmIf B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the 34238405SjkimPKCS7 structure, the signer's certificate must still be supplied in the 35238405SjkimB<signcert> parameter though. This can reduce the size of the signature if the 36238405Sjkimsigners certificate can be obtained by other means: for example a previously 37238405Sjkimsigned message. 38109998Smarkm 39238405SjkimThe data being signed is included in the PKCS7 structure, unless 40238405SjkimB<PKCS7_DETACHED> is set in which case it is omitted. This is used for PKCS7 41238405Sjkimdetached signatures which are used in S/MIME plaintext signed messages for 42238405Sjkimexample. 43109998Smarkm 44238405SjkimNormally the supplied content is translated into MIME canonical format (as 45238405Sjkimrequired by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation 46238405Sjkimoccurs. This option should be used if the supplied data is in binary format 47238405Sjkimotherwise the translation will corrupt it. 48109998Smarkm 49238405SjkimThe signedData structure includes several PKCS#7 autenticatedAttributes 50238405Sjkimincluding the signing time, the PKCS#7 content type and the supported list of 51238405Sjkimciphers in an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no 52238405SjkimauthenticatedAttributes will be used. If B<PKCS7_NOSMIMECAP> is set then just 53238405Sjkimthe SMIMECapabilities are omitted. 54109998Smarkm 55109998SmarkmIf present the SMIMECapabilities attribute indicates support for the following 56238405Sjkimalgorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of 57238405Sjkimthese algorithms is disabled then it will not be included. 58109998Smarkm 59238405SjkimIf the flags B<PKCS7_STREAM> is set then the returned B<PKCS7> structure is 60238405Sjkimjust initialized ready to perform the signing operation. The signing is however 61238405SjkimB<not> performed and the data to be signed is not read from the B<data> 62238405Sjkimparameter. Signing is deferred until after the data has been written. In this 63238405Sjkimway data can be signed in a single pass. 64160814Ssimon 65238405SjkimIf the B<PKCS7_PARTIAL> flag is set a partial B<PKCS7> structure is output to 66238405Sjkimwhich additional signers and capabilities can be added before finalization. 67238405Sjkim 68238405Sjkim 69160814Ssimon=head1 NOTES 70160814Ssimon 71238405SjkimIf the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not> 72238405Sjkimcomplete and outputting its contents via a function that does not properly 73238405Sjkimfinalize the B<PKCS7> structure will give unpredictable results. 74160814Ssimon 75238405SjkimSeveral functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(), 76238405SjkimPEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization 77238405Sjkimcan be performed by obtaining the streaming ASN1 B<BIO> directly using 78238405SjkimBIO_new_PKCS7(). 79160814Ssimon 80238405SjkimIf a signer is specified it will use the default digest for the signing 81238405Sjkimalgorithm. This is B<SHA1> for both RSA and DSA keys. 82109998Smarkm 83238405SjkimIn OpenSSL 1.0.0 the B<certs>, B<signcert> and B<pkey> parameters can all be 84238405SjkimB<NULL> if the B<PKCS7_PARTIAL> flag is set. One or more signers can be added 85238405Sjkimusing the function B<PKCS7_sign_add_signer()>. B<PKCS7_final()> must also be 86238405Sjkimcalled to finalize the structure if streaming is not enabled. Alternative 87238405Sjkimsigning digests can also be specified using this method. 88109998Smarkm 89238405SjkimIn OpenSSL 1.0.0 if B<signcert> and B<pkey> are NULL then a certificates only 90238405SjkimPKCS#7 structure is output. 91109998Smarkm 92238405SjkimIn versions of OpenSSL before 1.0.0 the B<signcert> and B<pkey> parameters must 93238405SjkimB<NOT> be NULL. 94109998Smarkm 95238405Sjkim=head1 BUGS 96109998Smarkm 97238405SjkimSome advanced attributes such as counter signatures are not supported. 98238405Sjkim 99109998Smarkm=head1 RETURN VALUES 100109998Smarkm 101238405SjkimPKCS7_sign() returns either a valid PKCS7 structure or NULL if an error 102238405Sjkimoccurred. The error can be obtained from ERR_get_error(3). 103109998Smarkm 104109998Smarkm=head1 SEE ALSO 105109998Smarkm 106109998SmarkmL<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_verify(3)|PKCS7_verify(3)> 107109998Smarkm 108109998Smarkm=head1 HISTORY 109109998Smarkm 110109998SmarkmPKCS7_sign() was added to OpenSSL 0.9.5 111109998Smarkm 112238405SjkimThe B<PKCS7_PARTIAL> flag was added in OpenSSL 1.0.0 113160814Ssimon 114238405SjkimThe B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0 115238405Sjkim 116109998Smarkm=cut 117