PKCS7_encrypt.pod 2.7 KB

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