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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 | ||