D2I_X509(3ossl) OpenSSL D2I_X509(3ossl)
NAME
d2i_ACCESS_DESCRIPTION, d2i_ADMISSIONS, d2i_ADMISSION_SYNTAX,
d2i_ASIdOrRange, d2i_ASIdentifierChoice, d2i_ASIdentifiers,
d2i_ASN1_BIT_STRING, d2i_ASN1_BMPSTRING, d2i_ASN1_ENUMERATED,
d2i_ASN1_GENERALIZEDTIME, d2i_ASN1_GENERALSTRING, d2i_ASN1_IA5STRING,
d2i_ASN1_INTEGER, d2i_ASN1_NULL, d2i_ASN1_OBJECT,
d2i_ASN1_OCTET_STRING, d2i_ASN1_PRINTABLE, d2i_ASN1_PRINTABLESTRING,
d2i_ASN1_SEQUENCE_ANY, d2i_ASN1_SET_ANY, d2i_ASN1_T61STRING,
d2i_ASN1_TIME, d2i_ASN1_TYPE, d2i_ASN1_UINTEGER,
d2i_ASN1_UNIVERSALSTRING, d2i_ASN1_UTCTIME, d2i_ASN1_UTF8STRING,
d2i_ASN1_VISIBLESTRING, d2i_ASRange, d2i_AUTHORITY_INFO_ACCESS,
d2i_AUTHORITY_KEYID, d2i_BASIC_CONSTRAINTS, d2i_CERTIFICATEPOLICIES,
d2i_CMS_ContentInfo, d2i_CMS_ReceiptRequest, d2i_CMS_bio,
d2i_CRL_DIST_POINTS, d2i_DHxparams, d2i_DIRECTORYSTRING,
d2i_DISPLAYTEXT, d2i_DIST_POINT, d2i_DIST_POINT_NAME, d2i_DSA_SIG,
d2i_ECDSA_SIG, d2i_ECPKParameters, d2i_EDIPARTYNAME, d2i_ESS_CERT_ID,
d2i_ESS_CERT_ID_V2, d2i_ESS_ISSUER_SERIAL, d2i_ESS_SIGNING_CERT,
d2i_ESS_SIGNING_CERT_V2, d2i_EXTENDED_KEY_USAGE, d2i_GENERAL_NAME,
d2i_GENERAL_NAMES, d2i_IPAddressChoice, d2i_IPAddressFamily,
d2i_IPAddressOrRange, d2i_IPAddressRange, d2i_ISSUER_SIGN_TOOL,
d2i_ISSUING_DIST_POINT, d2i_NAMING_AUTHORITY,
d2i_NETSCAPE_CERT_SEQUENCE, d2i_NETSCAPE_SPKAC, d2i_NETSCAPE_SPKI,
d2i_NOTICEREF, d2i_OCSP_BASICRESP, d2i_OCSP_CERTID,
d2i_OCSP_CERTSTATUS, d2i_OCSP_CRLID, d2i_OCSP_ONEREQ, d2i_OCSP_REQINFO,
d2i_OCSP_REQUEST, d2i_OCSP_RESPBYTES, d2i_OCSP_RESPDATA,
d2i_OCSP_RESPID, d2i_OCSP_RESPONSE, d2i_OCSP_REVOKEDINFO,
d2i_OCSP_SERVICELOC, d2i_OCSP_SIGNATURE, d2i_OCSP_SINGLERESP,
d2i_OSSL_AA_DIST_POINT, d2i_OSSL_ALLOWED_ATTRIBUTES_CHOICE,
d2i_OSSL_ALLOWED_ATTRIBUTES_ITEM, d2i_OSSL_ALLOWED_ATTRIBUTES_SYNTAX,
d2i_OSSL_ATAV, d2i_OSSL_ATTRIBUTE_DESCRIPTOR,
d2i_OSSL_ATTRIBUTE_MAPPING, d2i_OSSL_ATTRIBUTE_MAPPINGS,
d2i_OSSL_ATTRIBUTE_TYPE_MAPPING, d2i_OSSL_ATTRIBUTE_VALUE_MAPPING,
d2i_OSSL_ATTRIBUTES_SYNTAX, d2i_OSSL_AUTHORITY_ATTRIBUTE_ID_SYNTAX,
d2i_OSSL_BASIC_ATTR_CONSTRAINTS, d2i_OSSL_CMP_ATAVS, d2i_OSSL_CMP_MSG,
d2i_OSSL_CMP_PKIHEADER, d2i_OSSL_CMP_PKISI, d2i_OSSL_CRMF_CERTID,
d2i_OSSL_CRMF_CERTTEMPLATE, d2i_OSSL_CRMF_ENCRYPTEDKEY,
d2i_OSSL_CRMF_ENCRYPTEDVALUE, d2i_OSSL_CRMF_MSG, d2i_OSSL_CRMF_MSGS,
d2i_OSSL_CRMF_PBMPARAMETER, d2i_OSSL_CRMF_PKIPUBLICATIONINFO,
d2i_OSSL_CRMF_SINGLEPUBINFO, d2i_OSSL_DAY_TIME, d2i_OSSL_DAY_TIME_BAND,
d2i_OSSL_HASH, d2i_OSSL_IETF_ATTR_SYNTAX, d2i_OSSL_INFO_SYNTAX,
d2i_OSSL_INFO_SYNTAX_POINTER, d2i_OSSL_ISSUER_SERIAL,
d2i_OSSL_NAMED_DAY, d2i_OSSL_OBJECT_DIGEST_INFO,
d2i_OSSL_PRIVILEGE_POLICY_ID, d2i_OSSL_ROLE_SPEC_CERT_ID,
d2i_OSSL_ROLE_SPEC_CERT_ID_SYNTAX, d2i_OSSL_TARGET_CERT,
d2i_OSSL_TARGET, d2i_OSSL_TARGETING_INFORMATION, d2i_OSSL_TARGETS,
d2i_OSSL_TIME_PERIOD, d2i_OSSL_TIME_SPEC, d2i_OSSL_TIME_SPEC_ABSOLUTE,
d2i_OSSL_TIME_SPEC_DAY, d2i_OSSL_TIME_SPEC_MONTH,
d2i_OSSL_TIME_SPEC_TIME, d2i_OSSL_TIME_SPEC_WEEKS,
d2i_OSSL_TIME_SPEC_X_DAY_OF, d2i_OSSL_USER_NOTICE_SYNTAX,
d2i_OTHERNAME, d2i_PBE2PARAM, d2i_PBEPARAM, d2i_PBKDF2PARAM,
d2i_PBMAC1PARAM, d2i_PKCS12, d2i_PKCS12_BAGS, d2i_PKCS12_MAC_DATA,
d2i_PKCS12_SAFEBAG, d2i_PKCS12_bio, d2i_PKCS12_fp, d2i_PKCS7,
d2i_PKCS7_DIGEST, d2i_PKCS7_ENCRYPT, d2i_PKCS7_ENC_CONTENT,
d2i_PKCS7_ENVELOPE, d2i_PKCS7_ISSUER_AND_SERIAL, d2i_PKCS7_RECIP_INFO,
d2i_PKCS7_SIGNED, d2i_PKCS7_SIGNER_INFO, d2i_PKCS7_SIGN_ENVELOPE,
d2i_PKCS7_bio, d2i_PKCS7_fp, d2i_PKCS8_PRIV_KEY_INFO,
d2i_PKCS8_PRIV_KEY_INFO_bio, d2i_PKCS8_PRIV_KEY_INFO_fp, d2i_PKCS8_bio,
d2i_PKCS8_fp, d2i_PKEY_USAGE_PERIOD, d2i_POLICYINFO,
d2i_POLICYQUALINFO, d2i_PROFESSION_INFO, d2i_PROXY_CERT_INFO_EXTENSION,
d2i_PROXY_POLICY, d2i_RSA_OAEP_PARAMS, d2i_RSA_PSS_PARAMS,
d2i_SCRYPT_PARAMS, d2i_SCT_LIST, d2i_SXNET, d2i_SXNETID,
d2i_TS_ACCURACY, d2i_TS_MSG_IMPRINT, d2i_TS_MSG_IMPRINT_bio,
d2i_TS_MSG_IMPRINT_fp, d2i_TS_REQ, d2i_TS_REQ_bio, d2i_TS_REQ_fp,
d2i_TS_RESP, d2i_TS_RESP_bio, d2i_TS_RESP_fp, d2i_TS_STATUS_INFO,
d2i_TS_TST_INFO, d2i_TS_TST_INFO_bio, d2i_TS_TST_INFO_fp,
d2i_USERNOTICE, d2i_X509, d2i_X509_bio, d2i_X509_fp, d2i_X509_ACERT,
d2i_X509_ACERT_bio, d2i_X509_ACERT_fp, d2i_X509_ALGOR, d2i_X509_ALGORS,
d2i_X509_ATTRIBUTE, d2i_X509_CERT_AUX, d2i_X509_CINF, d2i_X509_CRL,
d2i_X509_CRL_INFO, d2i_X509_CRL_bio, d2i_X509_CRL_fp,
d2i_X509_EXTENSION, d2i_X509_EXTENSIONS, d2i_X509_NAME,
d2i_X509_NAME_ENTRY, d2i_X509_PUBKEY, d2i_X509_PUBKEY_bio,
d2i_X509_PUBKEY_fp, d2i_X509_REQ, d2i_X509_REQ_INFO, d2i_X509_REQ_bio,
d2i_X509_REQ_fp, d2i_X509_REVOKED, d2i_X509_SIG, d2i_X509_VAL,
i2d_ACCESS_DESCRIPTION, i2d_ADMISSIONS, i2d_ADMISSION_SYNTAX,
i2d_ASIdOrRange, i2d_ASIdentifierChoice, i2d_ASIdentifiers,
i2d_ASN1_BIT_STRING, i2d_ASN1_BMPSTRING, i2d_ASN1_ENUMERATED,
i2d_ASN1_GENERALIZEDTIME, i2d_ASN1_GENERALSTRING, i2d_ASN1_IA5STRING,
i2d_ASN1_INTEGER, i2d_ASN1_NULL, i2d_ASN1_OBJECT,
i2d_ASN1_OCTET_STRING, i2d_ASN1_PRINTABLE, i2d_ASN1_PRINTABLESTRING,
i2d_ASN1_SEQUENCE_ANY, i2d_ASN1_SET_ANY, i2d_ASN1_T61STRING,
i2d_ASN1_TIME, i2d_ASN1_TYPE, i2d_ASN1_UNIVERSALSTRING,
i2d_ASN1_UTCTIME, i2d_ASN1_UTF8STRING, i2d_ASN1_VISIBLESTRING,
i2d_ASN1_bio_stream, i2d_ASRange, i2d_AUTHORITY_INFO_ACCESS,
i2d_AUTHORITY_KEYID, i2d_BASIC_CONSTRAINTS, i2d_CERTIFICATEPOLICIES,
i2d_CMS_ContentInfo, i2d_CMS_ReceiptRequest, i2d_CMS_bio,
i2d_CRL_DIST_POINTS, i2d_DHxparams, i2d_DIRECTORYSTRING,
i2d_DISPLAYTEXT, i2d_DIST_POINT, i2d_DIST_POINT_NAME, i2d_DSA_SIG,
i2d_ECDSA_SIG, i2d_ECPKParameters, i2d_EDIPARTYNAME, i2d_ESS_CERT_ID,
i2d_ESS_CERT_ID_V2, i2d_ESS_ISSUER_SERIAL, i2d_ESS_SIGNING_CERT,
i2d_ESS_SIGNING_CERT_V2, i2d_EXTENDED_KEY_USAGE, i2d_GENERAL_NAME,
i2d_GENERAL_NAMES, i2d_IPAddressChoice, i2d_IPAddressFamily,
i2d_IPAddressOrRange, i2d_IPAddressRange, i2d_ISSUER_SIGN_TOOL,
i2d_ISSUING_DIST_POINT, i2d_NAMING_AUTHORITY,
i2d_NETSCAPE_CERT_SEQUENCE, i2d_NETSCAPE_SPKAC, i2d_NETSCAPE_SPKI,
i2d_NOTICEREF, i2d_OCSP_BASICRESP, i2d_OCSP_CERTID,
i2d_OCSP_CERTSTATUS, i2d_OCSP_CRLID, i2d_OCSP_ONEREQ, i2d_OCSP_REQINFO,
i2d_OCSP_REQUEST, i2d_OCSP_RESPBYTES, i2d_OCSP_RESPDATA,
i2d_OCSP_RESPID, i2d_OCSP_RESPONSE, i2d_OCSP_REVOKEDINFO,
i2d_OCSP_SERVICELOC, i2d_OCSP_SIGNATURE, i2d_OCSP_SINGLERESP,
i2d_OSSL_AA_DIST_POINT, i2d_OSSL_ALLOWED_ATTRIBUTES_CHOICE,
i2d_OSSL_ALLOWED_ATTRIBUTES_ITEM, i2d_OSSL_ALLOWED_ATTRIBUTES_SYNTAX,
i2d_OSSL_ATAV, i2d_OSSL_ATTRIBUTE_DESCRIPTOR,
i2d_OSSL_ATTRIBUTE_MAPPING, i2d_OSSL_ATTRIBUTE_MAPPINGS,
i2d_OSSL_ATTRIBUTE_TYPE_MAPPING, i2d_OSSL_ATTRIBUTE_VALUE_MAPPING,
i2d_OSSL_ATTRIBUTES_SYNTAX, i2d_OSSL_AUTHORITY_ATTRIBUTE_ID_SYNTAX,
i2d_OSSL_BASIC_ATTR_CONSTRAINTS, i2d_OSSL_CMP_ATAVS, i2d_OSSL_CMP_MSG,
i2d_OSSL_CMP_PKIHEADER, i2d_OSSL_CMP_PKISI, i2d_OSSL_CRMF_CERTID,
i2d_OSSL_CRMF_CERTTEMPLATE, i2d_OSSL_CRMF_ENCRYPTEDKEY,
i2d_OSSL_CRMF_ENCRYPTEDVALUE, i2d_OSSL_CRMF_MSG, i2d_OSSL_CRMF_MSGS,
i2d_OSSL_CRMF_PBMPARAMETER, i2d_OSSL_CRMF_PKIPUBLICATIONINFO,
i2d_OSSL_CRMF_SINGLEPUBINFO, i2d_OSSL_HASH, i2d_OSSL_DAY_TIME,
i2d_OSSL_DAY_TIME_BAND, i2d_OSSL_IETF_ATTR_SYNTAX,
i2d_OSSL_INFO_SYNTAX, i2d_OSSL_INFO_SYNTAX_POINTER,
i2d_OSSL_ISSUER_SERIAL, i2d_OSSL_NAMED_DAY,
i2d_OSSL_OBJECT_DIGEST_INFO, i2d_OSSL_PRIVILEGE_POLICY_ID,
i2d_OSSL_ROLE_SPEC_CERT_ID, i2d_OSSL_ROLE_SPEC_CERT_ID_SYNTAX,
i2d_OSSL_TARGET_CERT, i2d_OSSL_TARGET, i2d_OSSL_TARGETING_INFORMATION,
i2d_OSSL_TARGETS, i2d_OSSL_TIME_PERIOD, i2d_OSSL_TIME_SPEC,
i2d_OSSL_TIME_SPEC_ABSOLUTE, i2d_OSSL_TIME_SPEC_DAY,
i2d_OSSL_TIME_SPEC_MONTH, i2d_OSSL_TIME_SPEC_TIME,
i2d_OSSL_TIME_SPEC_WEEKS, i2d_OSSL_TIME_SPEC_X_DAY_OF,
i2d_OSSL_USER_NOTICE_SYNTAX, i2d_OTHERNAME, i2d_PBE2PARAM,
i2d_PBEPARAM, i2d_PBKDF2PARAM, i2d_PBMAC1PARAM, i2d_PKCS12,
i2d_PKCS12_BAGS, i2d_PKCS12_MAC_DATA, i2d_PKCS12_SAFEBAG,
i2d_PKCS12_bio, i2d_PKCS12_fp, i2d_PKCS7, i2d_PKCS7_DIGEST,
i2d_PKCS7_ENCRYPT, i2d_PKCS7_ENC_CONTENT, i2d_PKCS7_ENVELOPE,
i2d_PKCS7_ISSUER_AND_SERIAL, i2d_PKCS7_NDEF, i2d_PKCS7_RECIP_INFO,
i2d_PKCS7_SIGNED, i2d_PKCS7_SIGNER_INFO, i2d_PKCS7_SIGN_ENVELOPE,
i2d_PKCS7_bio, i2d_PKCS7_fp, i2d_PKCS8PrivateKeyInfo_bio,
i2d_PKCS8PrivateKeyInfo_fp, i2d_PKCS8_PRIV_KEY_INFO,
i2d_PKCS8_PRIV_KEY_INFO_bio, i2d_PKCS8_PRIV_KEY_INFO_fp, i2d_PKCS8_bio,
i2d_PKCS8_fp, i2d_PKEY_USAGE_PERIOD, i2d_POLICYINFO,
i2d_POLICYQUALINFO, i2d_PROFESSION_INFO, i2d_PROXY_CERT_INFO_EXTENSION,
i2d_PROXY_POLICY, i2d_RSA_OAEP_PARAMS, i2d_RSA_PSS_PARAMS,
i2d_SCRYPT_PARAMS, i2d_SCT_LIST, i2d_SXNET, i2d_SXNETID,
i2d_TS_ACCURACY, i2d_TS_MSG_IMPRINT, i2d_TS_MSG_IMPRINT_bio,
i2d_TS_MSG_IMPRINT_fp, i2d_TS_REQ, i2d_TS_REQ_bio, i2d_TS_REQ_fp,
i2d_TS_RESP, i2d_TS_RESP_bio, i2d_TS_RESP_fp, i2d_TS_STATUS_INFO,
i2d_TS_TST_INFO, i2d_TS_TST_INFO_bio, i2d_TS_TST_INFO_fp,
i2d_USERNOTICE, i2d_X509, i2d_X509_bio, i2d_X509_fp, i2d_X509_ACERT,
i2d_X509_ACERT_bio, i2d_X509_ACERT_fp, i2d_X509_ALGOR, i2d_X509_ALGORS,
i2d_X509_ATTRIBUTE, i2d_X509_CERT_AUX, i2d_X509_CINF, i2d_X509_CRL,
i2d_X509_CRL_INFO, i2d_X509_CRL_bio, i2d_X509_CRL_fp,
i2d_X509_EXTENSION, i2d_X509_EXTENSIONS, i2d_X509_NAME,
i2d_X509_NAME_ENTRY, i2d_X509_PUBKEY, i2d_X509_PUBKEY_bio,
i2d_X509_PUBKEY_fp, i2d_X509_REQ, i2d_X509_REQ_INFO, i2d_X509_REQ_bio,
i2d_X509_REQ_fp, i2d_X509_REVOKED, i2d_X509_SIG, i2d_X509_VAL, -
convert objects from/to ASN.1/DER representation
SYNOPSIS
TYPE *d2i_TYPE(TYPE **a, const unsigned char **ppin, long length);
TYPE *d2i_TYPE_bio(BIO *bp, TYPE **a);
TYPE *d2i_TYPE_fp(FILE *fp, TYPE **a);
int i2d_TYPE(const TYPE *a, unsigned char **ppout);
int i2d_TYPE(TYPE *a, unsigned char **ppout);
int i2d_TYPE_fp(FILE *fp, const TYPE *a);
int i2d_TYPE_fp(FILE *fp, TYPE *a);
int i2d_TYPE_bio(BIO *bp, const TYPE *a);
int i2d_TYPE_bio(BIO *bp, TYPE *a);
DESCRIPTION
In the description here, TYPE is used a placeholder for any of the
OpenSSL datatypes, such as X509_CRL. The function parameters ppin and
ppout are generally either both named pp in the headers, or in and out.
These functions convert OpenSSL objects to and from their ASN.1/DER
encoding. Unlike the C structures which can have pointers to
sub-objects within, the DER is a serialized encoding, suitable for
sending over the network, writing to a file, and so on.
d2i_TYPE() attempts to decode len bytes at *ppin. When there is no
error, a pointer to a TYPE object is returned and *ppin is incremented
to the byte following the parsed data. The caller owns the returned
object and needs to free it when it is no longer needed, e.g., via
X509_free() for X509 objects.
If either a or *a is NULL, then fresh storage is allocated for the
returned object, and if a is not NULL then *a is set equal to the
returned pointer.
When both a and *a are not NULL, *a MUST be a pointer to an existing
TYPE object, which is reused to hold the decoded result. On error
(NULL return value), the object is freed and *a is set to NULL.
From OpenSSL 3.x onwards, reuse is only supported when *a points to a
newly allocated, and not otherwise modified, TYPE object. Allocation
can be via one of the various _ex() routines, which make it possible to
associate the allocated object with a chosen libctx (library context)
or propq (property query), see the EXAMPLES section. No other reuse is
supported (see BUGS below, and the discussion in the RETURN VALUES
section). The returned object is not suitable for another reuse: each
reuse attempt MUST start with a newly allocated object.
d2i_TYPE_bio() is similar to d2i_TYPE() except it attempts to parse
data from BIO bp.
d2i_TYPE_fp() is similar to d2i_TYPE() except it attempts to parse data
from FILE pointer fp.
i2d_TYPE() encodes the structure pointed to by a into DER format. If
ppout is not NULL, it writes the DER encoded data to the buffer at
*ppout, and increments it to point after the data just written. If the
return value is negative an error occurred, otherwise it returns the
length of the encoded data.
If *ppout is NULL memory will be allocated for a buffer and the encoded
data written to it. In this case *ppout is not incremented and it
points to the start of the data just written.
i2d_TYPE_bio() is similar to i2d_TYPE() except it writes the encoding
of the structure a to BIO bp and it returns 1 for success and 0 for
failure.
i2d_TYPE_fp() is similar to i2d_TYPE() except it writes the encoding of
the structure a to FILE pointer fp and it returns 1 for success and 0
for failure.
These routines do not encrypt private keys and therefore offer no
security; use PEM_write_PrivateKey(3) or similar for writing to files.
NOTES
The letters i and d in i2d_TYPE() stand for "internal" (that is, an
internal C structure) and "DER" respectively. So i2d_TYPE() converts
from internal to DER.
The functions can also understand BER forms.
The actual TYPE structure passed to i2d_TYPE() must be a valid
populated TYPE structure -- it cannot simply be fed with an empty
structure such as that returned by TYPE_new().
The encoded data is in binary form and may contain embedded zeros.
Therefore, any FILE pointers or BIOs should be opened in binary mode.
Functions such as strlen() will not return the correct length of the
encoded structure.
The ways that *ppin and *ppout are incremented after the operation can
trap the unwary. See the WARNINGS section for some common errors. The
reason for this-auto increment behaviour is to reflect a typical usage
of ASN1 functions: after one structure is encoded or decoded another
will be processed after it.
The following points about the data types might be useful:
ASN1_OBJECT
Represents an ASN1 OBJECT IDENTIFIER.
DHparams
Represents a PKCS#3 DH parameters structure.
DHxparams
Represents an ANSI X9.42 DH parameters structure.
ECDSA_SIG
Represents an ECDSA signature.
X509_ALGOR
Represents an AlgorithmIdentifier structure as used in IETF RFC
6960 and elsewhere.
X509_NAME
Represents a Name type as used for subject and issuer names in IETF
RFC 6960 and elsewhere.
X509_REQ
Represents a PKCS#10 certificate request.
X509_SIG
Represents the DigestInfo structure defined in PKCS#1 and PKCS#7.
RETURN VALUES
d2i_TYPE(), d2i_TYPE_bio() and d2i_TYPE_fp() return a valid TYPE
structure or NULL if an error occurs. If the "reuse" capability has
been used with a valid structure being passed in via a, then the object
is freed in the event of error and *a is set to NULL.
i2d_TYPE() returns the number of bytes successfully encoded or a
negative value if an error occurs.
i2d_TYPE_bio() and i2d_TYPE_fp(), as well as i2d_ASN1_bio_stream(),
return 1 for success and 0 if an error occurs.
On error, these functions may record the error in the OpenSSL error
queue. That error queue can be inspected with the ERR family of
functions, such as ERR_print_errors(3) and ERR_peek_last_error_all(3).
EXAMPLES
Allocate and encode the DER encoding of an X509 structure:
int len;
unsigned char *buf;
buf = NULL;
len = i2d_X509(x, &buf);
if (len < 0)
/* error */
Attempt to decode a buffer:
X509 *x;
unsigned char *buf;
const unsigned char *p;
int len;
/* Set up buf and len to point to the input buffer. */
p = buf;
x = d2i_X509(NULL, &p, len);
if (x == NULL)
/* error */
Alternative technique:
X509 *x;
unsigned char *buf;
const unsigned char *p;
int len;
/* Set up buf and len to point to the input buffer. */
p = buf;
x = NULL;
if (d2i_X509(&x, &p, len) == NULL)
/* error */
Setting up a library context and property query:
X509 *x;
unsigned char *buf;
const unsigned char *p;
int len;
OSSL_LIB_CTX *libctx = ....;
const char *propq = ....;
/* Set up buf and len to point to the input buffer. */
p = buf;
x = X509_new_ex(libctx, propq);
if (d2i_X509(&x, &p, len) == NULL)
/* error, x was freed and NULL assigned to it (see RETURN VALUES) */
WARNINGS
Using a temporary variable is mandatory. A common mistake is to attempt
to use a buffer directly as follows:
int len;
unsigned char *buf;
len = i2d_X509(x, NULL);
buf = OPENSSL_malloc(len);
...
i2d_X509(x, &buf);
...
OPENSSL_free(buf);
This code will result in buf apparently containing garbage because it
was incremented after the call to point after the data just written.
Also buf will no longer contain the pointer allocated by
OPENSSL_malloc() and the subsequent call to OPENSSL_free() is likely to
crash.
Another trap to avoid is misuse of the a argument to d2i_TYPE():
X509 *x;
if (d2i_X509(&x, &p, len) == NULL)
/* error */
This will probably crash somewhere in d2i_X509(3). The reason for this
is that the variable x is uninitialized and an attempt will be made to
interpret its (invalid) value as an X509 structure, typically causing a
segmentation violation. If x is set to NULL first then this will not
happen.
BUGS
In some versions of OpenSSL the "reuse" behaviour of d2i_TYPE() when *a
is valid is broken and some parts of the reused structure may persist
if they are not present in the new one. Additionally, in versions of
OpenSSL prior to 1.1.0, when the "reuse" behaviour is used and an error
occurs the behaviour is inconsistent. Some functions behaved as
described here, while some did not free *a on error and did not set *a
to NULL.
As a result of the above issues the "reuse" behaviour is strongly
discouraged.
i2d_TYPE() will not return an error in many versions of OpenSSL, if
mandatory fields are not initialized due to a programming error then
the encoded structure may contain invalid data or omit the fields
entirely and will not be parsed by d2i_TYPE(). This may be fixed in
future so code should not assume that i2d_TYPE() will always succeed.
Any function which encodes a structure (i2d_TYPE(), i2d_TYPE_bio() or
i2d_TYPE_fp()) may return a stale encoding if the structure has been
modified after deserialization or previous serialization. This is
because some objects cache the encoding for efficiency reasons.
SEE ALSO
ERR_print_errors(3), ERR_peek_last_error_all(3)
HISTORY
d2i_OSSL_ATTRIBUTES_SYNTAX(), d2i_OSSL_BASIC_ATTR_CONSTRAINTS(),
d2i_OSSL_CMP_ATAVS(), d2i_OSSL_IETF_ATTR_SYNTAX(), d2i_OSSL_TARGET(),
d2i_OSSL_TARGETING_INFORMATION(), d2i_OSSL_TARGETS(),
d2i_OSSL_USER_NOTICE_SYNTAX(), d2i_PBMAC1PARAM(), d2i_X509_ACERT(),
d2i_X509_ACERT_bio(), d2i_X509_ACERT_fp(),
i2d_OSSL_ATTRIBUTES_SYNTAX(), i2d_OSSL_BASIC_ATTR_CONSTRAINTS(),
i2d_OSSL_CMP_ATAVS(), i2d_OSSL_IETF_ATTR_SYNTAX(), i2d_OSSL_TARGET(),
i2d_OSSL_TARGETING_INFORMATION(), i2d_OSSL_TARGETS(),
i2d_OSSL_USER_NOTICE_SYNTAX(), i2d_PBMAC1PARAM(), i2d_X509_ACERT(),
i2d_X509_ACERT_bio(), i2d_X509_ACERT_fp() were added in OpenSSL 3.4.
d2i_OSSL_AA_DIST_POINT(), d2i_OSSL_ALLOWED_ATTRIBUTES_CHOICE(),
d2i_OSSL_ALLOWED_ATTRIBUTES_ITEM(),
d2i_OSSL_ALLOWED_ATTRIBUTES_SYNTAX(), d2i_OSSL_ATAV(),
d2i_OSSL_ATTRIBUTE_DESCRIPTOR(), d2i_OSSL_ATTRIBUTE_MAPPING(),
d2i_OSSL_ATTRIBUTE_MAPPINGS(), d2i_OSSL_ATTRIBUTE_TYPE_MAPPING(),
d2i_OSSL_ATTRIBUTE_VALUE_MAPPING(),
d2i_OSSL_AUTHORITY_ATTRIBUTE_ID_SYNTAX(), d2i_OSSL_HASH(),
d2i_OSSL_INFO_SYNTAX(), d2i_OSSL_INFO_SYNTAX_POINTER(),
d2i_OSSL_PRIVILEGE_POLICY_ID(), d2i_OSSL_ROLE_SPEC_CERT_ID(),
d2i_OSSL_ROLE_SPEC_CERT_ID_SYNTAX(), i2d_OSSL_AA_DIST_POINT(),
i2d_OSSL_ALLOWED_ATTRIBUTES_CHOICE(),
i2d_OSSL_ALLOWED_ATTRIBUTES_ITEM(),
i2d_OSSL_ALLOWED_ATTRIBUTES_SYNTAX(), i2d_OSSL_ATAV(),
i2d_OSSL_ATTRIBUTE_DESCRIPTOR(), i2d_OSSL_ATTRIBUTE_MAPPING(),
i2d_OSSL_ATTRIBUTE_MAPPINGS(), i2d_OSSL_ATTRIBUTE_TYPE_MAPPING(),
i2d_OSSL_ATTRIBUTE_VALUE_MAPPING(),
i2d_OSSL_AUTHORITY_ATTRIBUTE_ID_SYNTAX(), i2d_OSSL_HASH(),
i2d_OSSL_INFO_SYNTAX(), i2d_OSSL_INFO_SYNTAX_POINTER(),
i2d_OSSL_PRIVILEGE_POLICY_ID(), i2d_OSSL_ROLE_SPEC_CERT_ID(),
i2d_OSSL_ROLE_SPEC_CERT_ID_SYNTAX(), d2i_OSSL_CRMF_ENCRYPTEDKEY(),
i2d_OSSL_CRMF_ENCRYPTEDKEY(), d2i_OSSL_DAY_TIME(),
d2i_OSSL_DAY_TIME_BAND(), d2i_OSSL_NAMED_DAY(), d2i_OSSL_TIME_PERIOD(),
d2i_OSSL_TIME_SPEC(), d2i_OSSL_TIME_SPEC_ABSOLUTE(),
d2i_OSSL_TIME_SPEC_DAY(), d2i_OSSL_TIME_SPEC_MONTH(),
d2i_OSSL_TIME_SPEC_TIME(), d2i_OSSL_TIME_SPEC_WEEKS(),
d2i_OSSL_TIME_SPEC_X_DAY_OF(), i2d_OSSL_DAY_TIME(),
i2d_OSSL_DAY_TIME_BAND(), i2d_OSSL_NAMED_DAY(), i2d_OSSL_TIME_PERIOD(),
i2d_OSSL_TIME_SPEC(), i2d_OSSL_TIME_SPEC_ABSOLUTE(),
i2d_OSSL_TIME_SPEC_DAY(), i2d_OSSL_TIME_SPEC_MONTH(),
i2d_OSSL_TIME_SPEC_TIME(), i2d_OSSL_TIME_SPEC_WEEKS(),
i2d_OSSL_TIME_SPEC_X_DAY_OF() were added in OpenSSL 3.5.
COPYRIGHT
Copyright 1998-2026 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.6.3 2026-06-09 D2I_X509(3ossl)
openssl 3.6.3 - Generated Wed Jun 10 07:49:21 CDT 2026