keyctl_dh_compute() computes a Diffie-Hellman public key or shared
secret. That computation is:
base ^ private ( mod prime )
When base is a key containing the shared generator value, the remote
public key is computed. When base is a key containing the remote
public key, the shared secret is computed.
base, private, and prime must all refer to user-type keys containing
the parameters for the computation. Each of these keys must grant
the caller read permission in order for them to be used.
buffer and buflen specify the buffer into which the computed result
will be placed. buflen may be zero, in which case the buffer is not
used and the minimum buffer length is fetched.
keyctl_dh_compute_alloc() is similar to keyctl_dh_compute() except
that it allocates a buffer big enough to hold the payload data and
places the data in it. If successful, a pointer to the buffer is
placed in *_buffer. The caller must free the buffer.
On success keyctl_dh_compute() returns the amount of data placed into
the buffer when buflen is non-zero. When buflen is zero, the minimum
buffer length to hold the data is returned.
On success keyctl_dh_compute_alloc() returns the amount of data in
On error, both functions set errno to an appropriate code and return
the value -1.
This page is part of the keyutils (key management utilities) project.
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Linux 07 Apr 2016 KEYCTL_DH_COMPUTE(3)