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.Dd May 15, 2022
.Dt CRYB_MD2 3
.Os
.Sh NAME
.Nm cryb_md2_init ,
.Nm cryb_md2_update ,
.Nm cryb_md2_final ,
.Nm cryb_md2_complete
.Nd Message-Digest Algorithm 2
.Sh LIBRARY
.Lb libcryb-digest
.Sh SYNOPSIS
.In stddef.h
.In stdint.h
.In cryb/md2.h
.Ft void
.Fn cryb_md2_init "cryb_md2_ctx *context"
.Ft void
.Fn cryb_md2_update "cryb_md2_ctx *context" "const void *data" "size_t len"
.Ft void
.Fn cryb_md2_final "cryb_md2_ctx *context" "uint8_t *digest"
.Ft void
.Fn cryb_md2_complete "const void *data" "size_t len" "uint8_t *digest"
.Sh DESCRIPTION
The
.Nm cryb_md2
family of functions implements the MD2 message digest algorithm as
described in RFC 1319.
.Pp
The
.Fn cryb_md2_init
function initializes the context structure pointed to by
.Va context .
It is the caller's responsibility to allocate this structure.
.Pp
The
.Fn cryb_md2_update
function hashes the next
.Va len
bytes of data pointed to by the
.Va data
pointer into the given hash context.
.Pp
The
.Fn cryb_md2_final
function finalizes the computation and writes the resulting message
digest to the caller-provided buffer pointed to by
.Va digest ,
which must be at least
.Dv MD2_DIGEST_LEN
bytes long.
It is the caller's responsibility to dispose of the context structure
after calling
.Fn cryb_md2_final .
.Pp
The
.Fn cryb_md2_complete
function is a shortcut to calling
.Fn cryb_md2_init ,
.Fn cryb_md2_update ,
and
.Fn cryb_md2_final
when the entire message is available up front in a single contiguous
buffer.
.Sh IMPLEMENTATION NOTES
The
.In cryb/md2.h
header provides macros which allows these functions and the context
type to be referred to without their
.Dq Li cryb_
prefix.
.Pp
The MD2 message digest algorithm has been proven to be vulnerable to
collision attacks and should not be used for cryptographic purposes.
.Sh SEE ALSO
.Xr cryb_digest 3 ,
.Xr cryb_md4 3 ,
.Xr cryb_md5 3
.Sh REFERENCES
.Rs
.%A Kaliski, Burton S.
.%T The MD2 Message-Digest Algorithm
.%D April 1992
.%O RFC 1319
.%U https://datatracker.ietf.org/doc/html/rfc1319
.Re
.Rs
.%A Turner, Sean
.%A Chen, Lily
.%T MD2 to Historic Status
.%D March 2011
.%O RFC 6149
.%U https://datatracker.ietf.org/doc/html/rfc6149
.Re
.Sh AUTHORS
These functions and this manual page were written by
.An Dag-Erling Sm\(/orgrav Aq Mt des@des.no .