Initial Commit

openssl-1.0.2f/doc/crypto/PKCS7_encrypt.pod

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+=pod
+
+=head1 NAME
+
+PKCS7_encrypt - create a PKCS#7 envelopedData structure
+
+=head1 SYNOPSIS
+
+ #include <openssl/pkcs7.h>
+
+ PKCS7 *PKCS7_encrypt(STACK_OF(X509) *certs, BIO *in, const EVP_CIPHER *cipher, int flags);
+
+=head1 DESCRIPTION
+
+PKCS7_encrypt() creates and returns a PKCS#7 envelopedData structure. B<certs>
+is a list of recipient certificates. B<in> is the content to be encrypted.
+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.
+
+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.
+
+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
+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.
+
+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(), i2d_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 PKCS7 structure or NULL if an error occurred.
+The error can be obtained from ERR_get_error(3).
+
+=head1 SEE ALSO
+
+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 1.0.0.
+
+=cut