5 d2i_ACCESS_DESCRIPTION,
9 d2i_ASIdentifierChoice,
14 d2i_ASN1_GENERALIZEDTIME,
15 d2i_ASN1_GENERALSTRING,
20 d2i_ASN1_OCTET_STRING,
22 d2i_ASN1_PRINTABLESTRING,
23 d2i_ASN1_SEQUENCE_ANY,
29 d2i_ASN1_UNIVERSALSTRING,
32 d2i_ASN1_VISIBLESTRING,
34 d2i_AUTHORITY_INFO_ACCESS,
36 d2i_BASIC_CONSTRAINTS,
37 d2i_CERTIFICATEPOLICIES,
39 d2i_CMS_ReceiptRequest,
48 d2i_DSAPrivateKey_bio,
67 d2i_ESS_ISSUER_SERIAL,
69 d2i_EXTENDED_KEY_USAGE,
76 d2i_ISSUING_DIST_POINT,
78 d2i_NETSCAPE_CERT_SEQUENCE,
110 d2i_PKCS7_ENC_CONTENT,
112 d2i_PKCS7_ISSUER_AND_SERIAL,
113 d2i_PKCS7_RECIP_INFO,
115 d2i_PKCS7_SIGNER_INFO,
116 d2i_PKCS7_SIGN_ENVELOPE,
119 d2i_PKCS8_PRIV_KEY_INFO,
120 d2i_PKCS8_PRIV_KEY_INFO_bio,
121 d2i_PKCS8_PRIV_KEY_INFO_fp,
124 d2i_PKEY_USAGE_PERIOD,
128 d2i_PROXY_CERT_INFO_EXTENSION,
131 d2i_RSAPrivateKey_bio,
132 d2i_RSAPrivateKey_fp,
134 d2i_RSAPublicKey_bio,
147 d2i_TS_MSG_IMPRINT_bio,
148 d2i_TS_MSG_IMPRINT_fp,
182 i2d_ACCESS_DESCRIPTION,
184 i2d_ADMISSION_SYNTAX,
186 i2d_ASIdentifierChoice,
191 i2d_ASN1_GENERALIZEDTIME,
192 i2d_ASN1_GENERALSTRING,
197 i2d_ASN1_OCTET_STRING,
199 i2d_ASN1_PRINTABLESTRING,
200 i2d_ASN1_SEQUENCE_ANY,
205 i2d_ASN1_UNIVERSALSTRING,
208 i2d_ASN1_VISIBLESTRING,
211 i2d_AUTHORITY_INFO_ACCESS,
213 i2d_BASIC_CONSTRAINTS,
214 i2d_CERTIFICATEPOLICIES,
216 i2d_CMS_ReceiptRequest,
225 i2d_DSAPrivateKey_bio,
226 i2d_DSAPrivateKey_fp,
237 i2d_ECPrivateKey_bio,
244 i2d_ESS_ISSUER_SERIAL,
245 i2d_ESS_SIGNING_CERT,
246 i2d_EXTENDED_KEY_USAGE,
251 i2d_IPAddressOrRange,
253 i2d_ISSUING_DIST_POINT,
254 i2d_NAMING_AUTHORITY,
255 i2d_NETSCAPE_CERT_SEQUENCE,
270 i2d_OCSP_REVOKEDINFO,
287 i2d_PKCS7_ENC_CONTENT,
289 i2d_PKCS7_ISSUER_AND_SERIAL,
291 i2d_PKCS7_RECIP_INFO,
293 i2d_PKCS7_SIGNER_INFO,
294 i2d_PKCS7_SIGN_ENVELOPE,
297 i2d_PKCS8PrivateKeyInfo_bio,
298 i2d_PKCS8PrivateKeyInfo_fp,
299 i2d_PKCS8_PRIV_KEY_INFO,
300 i2d_PKCS8_PRIV_KEY_INFO_bio,
301 i2d_PKCS8_PRIV_KEY_INFO_fp,
304 i2d_PKEY_USAGE_PERIOD,
308 i2d_PROXY_CERT_INFO_EXTENSION,
311 i2d_RSAPrivateKey_bio,
312 i2d_RSAPrivateKey_fp,
314 i2d_RSAPublicKey_bio,
327 i2d_TS_MSG_IMPRINT_bio,
328 i2d_TS_MSG_IMPRINT_fp,
362 - convert objects from/to ASN.1/DER representation
368 TYPE *d2i_TYPE(TYPE **a, const unsigned char **ppin, long length);
369 TYPE *d2i_TYPE_bio(BIO *bp, TYPE **a);
370 TYPE *d2i_TYPE_fp(FILE *fp, TYPE **a);
372 int i2d_TYPE(TYPE *a, unsigned char **ppout);
373 int i2d_TYPE_fp(FILE *fp, TYPE *a);
374 int i2d_TYPE_bio(BIO *bp, TYPE *a);
378 In the description here, I<TYPE> is used a placeholder
379 for any of the OpenSSL datatypes, such as I<X509_CRL>.
380 The function parameters I<ppin> and I<ppout> are generally
381 either both named I<pp> in the headers, or I<in> and I<out>.
383 These functions convert OpenSSL objects to and from their ASN.1/DER
384 encoding. Unlike the C structures which can have pointers to sub-objects
385 within, the DER is a serialized encoding, suitable for sending over the
386 network, writing to a file, and so on.
388 d2i_TYPE() attempts to decode B<len> bytes at B<*ppin>. If successful a
389 pointer to the B<TYPE> structure is returned and B<*ppin> is incremented to
390 the byte following the parsed data. If B<a> is not B<NULL> then a pointer
391 to the returned structure is also written to B<*a>. If an error occurred
392 then B<NULL> is returned.
394 On a successful return, if B<*a> is not B<NULL> then it is assumed that B<*a>
395 contains a valid B<TYPE> structure and an attempt is made to reuse it. This
396 "reuse" capability is present for historical compatibility but its use is
397 B<strongly discouraged> (see BUGS below, and the discussion in the RETURN
400 d2i_TYPE_bio() is similar to d2i_TYPE() except it attempts
401 to parse data from BIO B<bp>.
403 d2i_TYPE_fp() is similar to d2i_TYPE() except it attempts
404 to parse data from FILE pointer B<fp>.
406 i2d_TYPE() encodes the structure pointed to by B<a> into DER format.
407 If B<ppout> is not B<NULL>, it writes the DER encoded data to the buffer
408 at B<*ppout>, and increments it to point after the data just written.
409 If the return value is negative an error occurred, otherwise it
410 returns the length of the encoded data.
412 If B<*ppout> is B<NULL> memory will be allocated for a buffer and the encoded
413 data written to it. In this case B<*ppout> is not incremented and it points
414 to the start of the data just written.
416 i2d_TYPE_bio() is similar to i2d_TYPE() except it writes
417 the encoding of the structure B<a> to BIO B<bp> and it
418 returns 1 for success and 0 for failure.
420 i2d_TYPE_fp() is similar to i2d_TYPE() except it writes
421 the encoding of the structure B<a> to BIO B<bp> and it
422 returns 1 for success and 0 for failure.
424 These routines do not encrypt private keys and therefore offer no
425 security; use L<PEM_write_PrivateKey(3)> or similar for writing to files.
429 The letters B<i> and B<d> in B<i2d_TYPE> stand for
430 "internal" (that is, an internal C structure) and "DER" respectively.
431 So B<i2d_TYPE> converts from internal to DER.
433 The functions can also understand B<BER> forms.
435 The actual TYPE structure passed to i2d_TYPE() must be a valid
436 populated B<TYPE> structure -- it B<cannot> simply be fed with an
437 empty structure such as that returned by TYPE_new().
439 The encoded data is in binary form and may contain embedded zeros.
440 Therefore, any FILE pointers or BIOs should be opened in binary mode.
441 Functions such as strlen() will B<not> return the correct length
442 of the encoded structure.
444 The ways that B<*ppin> and B<*ppout> are incremented after the operation
445 can trap the unwary. See the B<WARNINGS> section for some common
447 The reason for this-auto increment behaviour is to reflect a typical
448 usage of ASN1 functions: after one structure is encoded or decoded
449 another will be processed after it.
451 The following points about the data types might be useful:
457 Represents an ASN1 OBJECT IDENTIFIER.
461 Represents a PKCS#3 DH parameters structure.
465 Represents an ANSI X9.42 DH parameters structure.
469 Represents a DSA public key using a B<SubjectPublicKeyInfo> structure.
471 =item B<DSAPublicKey, DSAPrivateKey>
473 Use a non-standard OpenSSL format and should be avoided; use B<DSA_PUBKEY>,
474 B<PEM_write_PrivateKey(3)>, or similar instead.
478 Represents an ECDSA signature.
480 =item B<RSAPublicKey>
482 Represents a PKCS#1 RSA public key structure.
486 Represents an B<AlgorithmIdentifier> structure as used in IETF RFC 6960 and
491 Represents a B<Name> type as used for subject and issuer names in
492 IETF RFC 6960 and elsewhere.
496 Represents a PKCS#10 certificate request.
500 Represents the B<DigestInfo> structure defined in PKCS#1 and PKCS#7.
506 d2i_TYPE(), d2i_TYPE_bio() and d2i_TYPE_fp() return a valid B<TYPE> structure
507 or B<NULL> if an error occurs. If the "reuse" capability has been used with
508 a valid structure being passed in via B<a>, then the object is freed in
509 the event of error and B<*a> is set to NULL.
511 i2d_TYPE() returns the number of bytes successfully encoded or a negative
512 value if an error occurs.
514 i2d_TYPE_bio() and i2d_TYPE_fp() return 1 for success and 0 if an error
519 Allocate and encode the DER encoding of an X509 structure:
525 len = i2d_X509(x, &buf);
529 Attempt to decode a buffer:
533 const unsigned char *p;
536 /* Set up buf and len to point to the input buffer. */
538 x = d2i_X509(NULL, &p, len);
542 Alternative technique:
546 const unsigned char *p;
549 /* Set up buf and len to point to the input buffer. */
553 if (d2i_X509(&x, &p, len) == NULL)
558 Using a temporary variable is mandatory. A common
559 mistake is to attempt to use a buffer directly as follows:
564 len = i2d_X509(x, NULL);
565 buf = OPENSSL_malloc(len);
571 This code will result in B<buf> apparently containing garbage because
572 it was incremented after the call to point after the data just written.
573 Also B<buf> will no longer contain the pointer allocated by OPENSSL_malloc()
574 and the subsequent call to OPENSSL_free() is likely to crash.
576 Another trap to avoid is misuse of the B<a> argument to d2i_TYPE():
580 if (d2i_X509(&x, &p, len) == NULL)
583 This will probably crash somewhere in d2i_X509(). The reason for this
584 is that the variable B<x> is uninitialized and an attempt will be made to
585 interpret its (invalid) value as an B<X509> structure, typically causing
586 a segmentation violation. If B<x> is set to NULL first then this will not
591 In some versions of OpenSSL the "reuse" behaviour of d2i_TYPE() when
592 B<*a> is valid is broken and some parts of the reused structure may
593 persist if they are not present in the new one. Additionally, in versions of
594 OpenSSL prior to 1.1.0, when the "reuse" behaviour is used and an error occurs
595 the behaviour is inconsistent. Some functions behaved as described here, while
596 some did not free B<*a> on error and did not set B<*a> to NULL.
598 As a result of the above issues the "reuse" behaviour is strongly discouraged.
600 i2d_TYPE() will not return an error in many versions of OpenSSL,
601 if mandatory fields are not initialized due to a programming error
602 then the encoded structure may contain invalid data or omit the
603 fields entirely and will not be parsed by d2i_TYPE(). This may be
604 fixed in future so code should not assume that i2d_TYPE() will
607 Any function which encodes a structure (i2d_TYPE(),
608 i2d_TYPE() or i2d_TYPE()) may return a stale encoding if the
609 structure has been modified after deserialization or previous
610 serialization. This is because some objects cache the encoding for
615 Copyright 1998-2020 The OpenSSL Project Authors. All Rights Reserved.
617 Licensed under the OpenSSL license (the "License"). You may not use
618 this file except in compliance with the License. You can obtain a copy
619 in the file LICENSE in the source distribution or at
620 L<https://www.openssl.org/source/license.html>.