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| 1 | =pod | ||
| 2 | |||
| 3 | =head1 NAME | ||
| 4 | |||
| 5 | PKCS7_encrypt - create a PKCS#7 envelopedData structure | ||
| 6 | |||
| 7 | =head1 SYNOPSIS | ||
| 8 | |||
| 9 | #include <openssl/pkcs7.h> | ||
| 10 | |||
| 11 | PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, int flags); | ||
| 12 | |||
| 13 | =head1 DESCRIPTION | ||
| 14 | |||
| 15 | PKCS7_encrypt() creates and returns a PKCS#7 envelopedData structure. B<certs> | ||
| 16 | is a list of recipient certificates. B<in> is the content to be encrypted. | ||
| 17 | B<cipher> is the symmetric cipher to use. B<flags> is an optional set of flags. | ||
| 18 | |||
| 19 | =head1 NOTES | ||
| 20 | |||
| 21 | Only RSA keys are supported in PKCS#7 and envelopedData so the recipient | ||
| 22 | certificates supplied to this function must all contain RSA public keys, though | ||
| 23 | they do not have to be signed using the RSA algorithm. | ||
| 24 | |||
| 25 | EVP_des_ede3_cbc() (triple DES) is the algorithm of choice for S/MIME use | ||
| 26 | because most clients will support it. | ||
| 27 | |||
| 28 | Some old "export grade" clients may only support weak encryption using 40 or 64 | ||
| 29 | bit RC2. These can be used by passing EVP_rc2_40_cbc() and EVP_rc2_64_cbc() | ||
| 30 | respectively. | ||
| 31 | |||
| 32 | The algorithm passed in the B<cipher> parameter must support ASN1 encoding of | ||
| 33 | its parameters. | ||
| 34 | |||
| 35 | Many browsers implement a "sign and encrypt" option which is simply an S/MIME | ||
| 36 | envelopedData containing an S/MIME signed message. This can be readily produced | ||
| 37 | by storing the S/MIME signed message in a memory BIO and passing it to | ||
| 38 | PKCS7_encrypt(). | ||
| 39 | |||
| 40 | The following flags can be passed in the B<flags> parameter. | ||
| 41 | |||
| 42 | If the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are | ||
| 43 | prepended to the data. | ||
| 44 | |||
| 45 | Normally the supplied content is translated into MIME canonical format (as | ||
| 46 | required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation | ||
| 47 | occurs. This option should be used if the supplied data is in binary format | ||
| 48 | otherwise the translation will corrupt it. If B<PKCS7_BINARY> is set then | ||
| 49 | B<PKCS7_TEXT> is ignored. | ||
| 50 | |||
| 51 | If the B<PKCS7_STREAM> flag is set a partial B<PKCS7> structure is output | ||
| 52 | suitable for streaming I/O: no data is read from the BIO B<in>. | ||
| 53 | |||
| 54 | =head1 NOTES | ||
| 55 | |||
| 56 | If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not> | ||
| 57 | complete and outputting its contents via a function that does not | ||
| 58 | properly finalize the B<PKCS7> structure will give unpredictable | ||
| 59 | results. | ||
| 60 | |||
| 61 | Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(), | ||
| 62 | PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization | ||
| 63 | can be performed by obtaining the streaming ASN1 B<BIO> directly using | ||
| 64 | BIO_new_PKCS7(). | ||
| 65 | |||
| 66 | =head1 RETURN VALUES | ||
| 67 | |||
| 68 | PKCS7_encrypt() returns either a PKCS7 structure or NULL if an error occurred. | ||
| 69 | The error can be obtained from ERR_get_error(3). | ||
| 70 | |||
| 71 | =head1 SEE ALSO | ||
| 72 | |||
| 73 | L<ERR_get_error(3)|ERR_get_error(3)>, L<PKCS7_decrypt(3)|PKCS7_decrypt(3)> | ||
| 74 | |||
| 75 | =head1 HISTORY | ||
| 76 | |||
| 77 | PKCS7_decrypt() was added to OpenSSL 0.9.5 | ||
| 78 | The B<PKCS7_STREAM> flag was first supported in OpenSSL 1.0.0. | ||
| 79 | |||
| 80 | =cut | ||
