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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | LINKING | SEE ALSO | COLOPHON |
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KEYCTL_PKEY_SIGN(3) Linux Public-Key Signatures KEYCTL_PKEY_SIGN(3)
keyctl_pkey_sign, keyctl_pkey_verify - Generate and verify
signatures
#include <keyutils.h>
long keyctl_pkey_sign(key_serial_t key, const char *info,
const void *data, size_t data_len,
void *sig, size_t sig_len);
long keyctl_pkey_verify(key_serial_t key, const char *info,
const void *data, size_t data_len,
const void *sig, size_t sig_len);
keyctl_pkey_sign() asks the kernel to use the crypto data
attached to a key to generate a detached signature for a blob of
data. Note that this may involve calling out to cryptographic
hardware.
keyctl_pkey_verify() asks the kernel to use the key to generate a
verify the signature against the same blob of data. This may
also involve calling out to cryptographic hardware.
The caller must have search permission on a key to be able to
perform either operation.
When invoking the function, key indicates the key that will
provide the cryptographic material and info points to a space- or
tab-separated string of "key[=value]" parameters that indicate
things like encoding forms and passwords to unlock the key; see
asymmetric-key(7) for more information.
data and datalen indicate the address and size of the buffer of
data to be signed and sig and siglen indicate the address and
size of the signature buffer. The sign function draws data from
the data buffer, generates a signature from it and places the
output into the signature buffer. The verify function also draws
data from the data buffer, then decrypts the signature and
compares the result.
Note that the data buffer is strictly limited in capacity,
typically unable to hold more bits than the size of the key. The
caller is expected to have pre-digested the actual data and will
thus pass the digest output to this function. The name of the
digest used should be passed as part of the info string as
hash=<name> for use in constructing the signature metadata.
keyctl_pkey_query(2) can be called to find out how large the
buffers need to be and what the maximum size of the data can be
for a specific signature encoding.
Note that not all asymmetric-type keys will support these
operations; further, the operations available may depend on which
components of the key material are available: typically
encryption only requires the public key, but decryption requires
the private key as well. Which operations are supported on a
particular key can also be determined using the query function.
On success keyctl_pkey_sign() returns the amount of data written
into the signature buffer. keyctl_pkey_verify() will return 0 in
this case as it doesn't write to userspace.
On error the value -1 will be returned and errno will have been
set to an appropriate error.
ENOKEY The key specified is invalid.
EKEYEXPIRED
The key specified has expired.
EKEYREVOKED
The key specified has been revoked.
EACCES The key exists, but is not searchable by the calling
process.
EINVAL, EBADMSG, EOVERFLOW
Some part of the key material or signature data is bad.
EKEYREJECTED
Signature verification failed.
ENOPKG Some facility needed to complete the requested operation
is not available. This is most probably a requested or
required digest or encryption algorithm.
EFAULT Bad address.
This is a library function that can be found in libkeyutils.
When linking, -lkeyutils should be specified to the linker.
keyctl(1), add_key(2), keyctl(2), keyctl(3),
keyctl_pkey_query(3), keyrings(7), keyutils(7)
This page is part of the keyutils (key management utilities)
project. Information about the project can be found at [unknown
-- if you know, please contact man-pages@man7.org] If you have a
bug report for this manual page, send it to
keyrings@linux-nfs.org. This page was obtained from the
project's upstream Git repository
⟨http://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git⟩
on 2024-06-14. (At that time, the date of the most recent commit
that was found in the repository was 2023-03-20.) If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for
the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original
manual page), send a mail to man-pages@man7.org
Linux 8 Nov 2018 KEYCTL_PKEY_SIGN(3)
Pages that refer to this page: keyctl(3), keyctl_pkey_encrypt(3), keyctl_pkey_query(3), asymmetric-key(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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