PKCS7_sign.pod 5.1 KB

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  1. =pod
  2. =head1 NAME
  3. PKCS7_sign_ex, PKCS7_sign
  4. - create a PKCS#7 signedData structure
  5. =head1 SYNOPSIS
  6. #include <openssl/pkcs7.h>
  7. PKCS7 *PKCS7_sign_ex(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
  8. BIO *data, int flags, OPENSSL_CTX *libctx,
  9. const char *propq);
  10. PKCS7 *PKCS7_sign(X509 *signcert, EVP_PKEY *pkey, STACK_OF(X509) *certs,
  11. BIO *data, int flags);
  12. =head1 DESCRIPTION
  13. PKCS7_sign_ex() creates and returns a PKCS#7 signedData structure.
  14. I<igncert> is the certificate to sign with, Ipkey> is the corresponding
  15. private key. I<certs> is an optional additional set of certificates to include
  16. in the PKCS#7 structure (for example any intermediate CAs in the chain). The
  17. library context I<libctx> and property query I<propq> are used when
  18. retrieving algorithms from providers.
  19. The data to be signed is read from BIO B<data>.
  20. B<flags> is an optional set of flags.
  21. Any of the following flags (ored together) can be passed in the B<flags>
  22. parameter.
  23. Many S/MIME clients expect the signed content to include valid MIME headers. If
  24. the B<PKCS7_TEXT> flag is set MIME headers for type B<text/plain> are prepended
  25. to the data.
  26. If B<PKCS7_NOCERTS> is set the signer's certificate will not be included in the
  27. PKCS7 structure, the signer's certificate must still be supplied in the
  28. B<signcert> parameter though. This can reduce the size of the signature if the
  29. signers certificate can be obtained by other means: for example a previously
  30. signed message.
  31. The data being signed is included in the PKCS7 structure, unless
  32. B<PKCS7_DETACHED> is set in which case it is omitted. This is used for PKCS7
  33. detached signatures which are used in S/MIME plaintext signed messages for
  34. example.
  35. Normally the supplied content is translated into MIME canonical format (as
  36. required by the S/MIME specifications) if B<PKCS7_BINARY> is set no translation
  37. occurs. This option should be used if the supplied data is in binary format
  38. otherwise the translation will corrupt it.
  39. The signedData structure includes several PKCS#7 authenticatedAttributes
  40. including the signing time, the PKCS#7 content type and the supported list of
  41. ciphers in an SMIMECapabilities attribute. If B<PKCS7_NOATTR> is set then no
  42. authenticatedAttributes will be used. If B<PKCS7_NOSMIMECAP> is set then just
  43. the SMIMECapabilities are omitted.
  44. If present the SMIMECapabilities attribute indicates support for the following
  45. algorithms: triple DES, 128 bit RC2, 64 bit RC2, DES and 40 bit RC2. If any of
  46. these algorithms is disabled then it will not be included.
  47. If the flags B<PKCS7_STREAM> is set then the returned B<PKCS7> structure is
  48. just initialized ready to perform the signing operation. The signing is however
  49. B<not> performed and the data to be signed is not read from the B<data>
  50. parameter. Signing is deferred until after the data has been written. In this
  51. way data can be signed in a single pass.
  52. If the B<PKCS7_PARTIAL> flag is set a partial B<PKCS7> structure is output to
  53. which additional signers and capabilities can be added before finalization.
  54. If the flag B<PKCS7_STREAM> is set the returned B<PKCS7> structure is B<not>
  55. complete and outputting its contents via a function that does not properly
  56. finalize the B<PKCS7> structure will give unpredictable results.
  57. Several functions including SMIME_write_PKCS7(), i2d_PKCS7_bio_stream(),
  58. PEM_write_bio_PKCS7_stream() finalize the structure. Alternatively finalization
  59. can be performed by obtaining the streaming ASN1 B<BIO> directly using
  60. BIO_new_PKCS7().
  61. If a signer is specified it will use the default digest for the signing
  62. algorithm. This is B<SHA1> for both RSA and DSA keys.
  63. The B<certs>, B<signcert> and B<pkey> parameters can all be
  64. B<NULL> if the B<PKCS7_PARTIAL> flag is set. One or more signers can be added
  65. using the function PKCS7_sign_add_signer(). PKCS7_final() must also be
  66. called to finalize the structure if streaming is not enabled. Alternative
  67. signing digests can also be specified using this method.
  68. If B<signcert> and B<pkey> are NULL then a certificates only
  69. PKCS#7 structure is output.
  70. In versions of OpenSSL before 1.0.0 the B<signcert> and B<pkey> parameters must
  71. B<NOT> be NULL.
  72. PKCS7_sign() is similar to PKCS7_sign_ex() but uses default values of
  73. NULL for the library context I<libctx> and the property query I<propq>.
  74. =head1 BUGS
  75. Some advanced attributes such as counter signatures are not supported.
  76. =head1 RETURN VALUES
  77. PKCS7_sign_ex() and PKCS7_sign() return either a valid PKCS7 structure
  78. or NULL if an error occurred. The error can be obtained from ERR_get_error(3).
  79. =head1 SEE ALSO
  80. L<ERR_get_error(3)>, L<PKCS7_verify(3)>
  81. =head1 HISTORY
  82. The function PKCS7_sign_ex() was added in OpenSSL 3.0.
  83. The B<PKCS7_PARTIAL> flag, and the ability for B<certs>, B<signcert>,
  84. and B<pkey> parameters to be B<NULL> were added in OpenSSL 1.0.0.
  85. The B<PKCS7_STREAM> flag was added in OpenSSL 1.0.0.
  86. =head1 COPYRIGHT
  87. Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.
  88. Licensed under the Apache License 2.0 (the "License"). You may not use
  89. this file except in compliance with the License. You can obtain a copy
  90. in the file LICENSE in the source distribution or at
  91. L<https://www.openssl.org/source/license.html>.
  92. =cut