PKCS7_DATAINIT(3) | Library Functions Manual | PKCS7_DATAINIT(3) |
PKCS7_dataInit
—
construct a BIO chain for adding or retrieving
content
#include
<openssl/pkcs7.h>
BIO *
PKCS7_dataInit
(PKCS7 *p7,
BIO *indata);
PKCS7_dataInit
()
constructs a BIO chain in preparation for putting data into or retrieving
data out of p7. Depending on the
contentType of p7, the created
chain starts with:
One additional BIO is appended to the end of the chain, depending on the first condition that holds in the following list:
NULL
. This only makes sense while verifying a
detached signature, in which case indata is expected
to supply the content associated with the detached signature.PKCS7_dataInit
()
attaches the end of the chain to the nested content of
p7.Before calling PKCS7_dataInit
() in order
to add content, PKCS7_new(3),
PKCS7_set_type(3), and
PKCS7_content_new(3) are
typically required to create p7, to choose its desired
type, and to allocate the nested ContentInfo
structure. Alternatively, for SignedData,
PKCS7_sign(3) can be used with the
PKCS7_PARTIAL
or
PKCS7_STREAM
flags or for
EnvelopedData,
PKCS7_encrypt(3) with the
PKCS7_STREAM
flag.
After calling
PKCS7_dataInit
(),
the desired data can be written into the returned BIO,
BIO_flush(3) can be called on it,
PKCS7_dataFinal(3) can be used
to transfer the processed data from the returned memory BIO to the
p7 structure, and the chain can finally be destroyed
with BIO_free_all(3).
While
PKCS7_dataInit
()
does support the EnvelopedData and
SignedAndEnvelopedData types, using it for these types
is awkward and error prone except when using
PKCS7_encrypt(3) for the setup
because PKCS7_content_new(3)
does not support these two types. So in addition to creating
p7 itself and setting its type, the nested
ContentInfo structure also needs to be constructed
with PKCS7_new(3) and
PKCS7_set_type(3) and manually
inserted into the correct field of the respective sub-structure of
p7.
PKCS7_dataInit
() can also be called on a
fully populated object of type SignedData or
DigestedData. After that,
BIO_read(3) can be used to retrieve
data from it. In this use case, do not call
PKCS7_dataFinal(3); simply
proceed directly to BIO_free_all(3)
after reading the data.
PKCS7_dataInit
() returns a BIO chain on
success or NULL
on failure. It fails if
p7 is NULL
, if the
content field of p7 is empty, if
the contentType of p7 is
unsupported, if a cipher is required but none is configured, or if any
required operation fails, for example due to lack of memory or for various
other reasons.
BIO_new(3), BIO_read(3), PKCS7_content_new(3), PKCS7_dataFinal(3), PKCS7_encrypt(3), PKCS7_final(3), PKCS7_new(3), PKCS7_set_type(3), PKCS7_sign(3)
PKCS7_dataInit
() first appeared in SSLeay
0.8.1 and has been available since OpenBSD 2.4.
This function does not support EncryptedData.
If p7 is a fully populated structure
containing EnvelopedData,
SignedAndEnvelopedData, or arbitrary data,
PKCS7_dataInit
() returns a BIO chain that ultimately
reads from an empty memory BIO, so reading from it will instantly return an
end-of-file indication rather than reading the actual data contained in
p7.
June 3, 2020 | OpenBSD-current |