.Dd October 17, 2015
.\" Please adjust this date whenever you revise the manpage.
.Dt BLAKE2 3
.Os
.Sh NAME
.Nm blake2s ,
.Nm blake2b ,
.Nm blake2sp ,
.Nm blake2bp ,
.Nm blake2s_init ,
.Nm blake2s_init_key ,
.Nm blake2s_init_param ,
.Nm blake2s_update ,
.Nm blake2s_final ,
.Nm blake2b_init ,
.Nm blake2b_init_key ,
.Nm blake2b_init_param ,
.Nm blake2b_update ,
.Nm blake2b_final ,
.Nm blake2sp_init ,
.Nm blake2sp_init_key ,
.Nm blake2sp_update ,
.Nm blake2sp_final ,
.Nm blake2bp_init ,
.Nm blake2bp_init_key ,
.Nm blake2bp_update ,
.Nm blake2bp_final
.Nd BLAKE2 cryptographic hash function
.Sh LIBRARY
.ds str-Lb-libb2 BLAKE2 cryptographic hash function implementation (libb2, \-lb2)
.Lb libb2
.Sh SYNOPSIS
.In blake2.h
.Ft int
.Fn blake2s "uint8_t *out" "const void *in" "const void *key" "size_t outlen" "size_t inlen" "size_t keylen"
.Ft int
.Fn blake2b "uint8_t *out" "const void *in" "const void *key" "size_t outlen" "size_t inlen" "size_t keylen"
.Ft int
.Fn blake2sp "uint8_t *out" "const void *in" "const void *key" "size_t outlen" "size_t inlen" "size_t keylen"
.Ft int
.Fn blake2bp "uint8_t *out" "const void *in" "const void *key" "size_t outlen" "size_t inlen" "size_t keylen"
.\"
.Ft int
.Fn blake2s_init "blake2s_state *S" "size_t outlen"
.Ft int
.Fn blake2s_init_key "blake2s_state *S" "size_t outlen" "const void *key" "size_t keylen"
.Ft int
.Fn blake2s_init_param "blake2s_state *S" "const blake2s_param *P"
.Ft int
.Fn blake2s_update "blake2s_state *S" "const uint8_t *in" "size_t inlen"
.Ft int
.Fn blake2s_final "blake2s_state *S" "uint8_t *out" "size_t outlen"
.\"
.Ft int
.Fn blake2b_init "blake2b_state *S" "size_t outlen"
.Ft int
.Fn blake2b_init_key "blake2b_state *S" "size_t outlen" "const void *key" "size_t keylen"
.Ft int
.Fn blake2b_init_param "blake2b_state *S" "const blake2b_param *P"
.Ft int
.Fn blake2b_update "blake2b_state *S" "const uint8_t *in" "size_t inlen"
.Ft int
.Fn blake2b_final "blake2b_state *S" "uint8_t *out" "size_t outlen"
.\"
.Ft int
.Fn blake2sp_init "blake2sp_state *S" "size_t outlen"
.Ft int
.Fn blake2sp_init_key "blake2sp_state *S" "size_t outlen" "const void *key" "size_t keylen"
.Ft int
.Fn blake2sp_update "blake2sp_state *S" "const uint8_t *in" "size_t inlen"
.Ft int
.Fn blake2sp_final "blake2sp_state *S" "uint8_t *out" "size_t outlen"
.\"
.Ft int
.Fn blake2bp_init "blake2bp_state *S" "size_t outlen"
.Ft int
.Fn blake2bp_init_key "blake2bp_state *S" "size_t outlen" "const void *key" "size_t keylen"
.Ft int
.Fn blake2bp_update "blake2bp_state *S" "const uint8_t *in" "size_t inlen"
.Ft int
.Fn blake2bp_final "blake2bp_state *S" "uint8_t *out" "size_t outlen"
.\"
.Sh DESCRIPTION
The BLAKE2 family of cryptographic hash functions is an improved
version of the SHA-3 finalist BLAKE.
.Pp
BLAKE2b is optimized for 64-bit platforms and produces up to 64 bytes
of output; BLAKE2s is optimized for 32-bit platforms and produces up
to 32 bytes of output.
.Pp
BLAKE2bp and BLAKE2sp are parallel versions of BLAKE2b and BLAKE2s
designed for increased performance on multicore and large-vector SIMD
processors.
.\"
.Pp
The
.Fn blake2s_init ,
.Fn blake2b_init ,
.Fn blake2sp_init ,
and
.Fn blake2bp_init
functions initialize a hash state
.Fa S
to hash a message to an output of
.Fa outlen
bytes,
without using a key.
.\"
.Pp
.Fa S
must be allocated by the caller.
.\"
.Pp
The
.Fn blake2s_init_key ,
.Fn blake2b_init_key ,
.Fn blake2sp_init_key ,
and
.Fn blake2bp_init_key
functions initialize a hash state
.Fa S
to hash a message to an output of
.Fa outlen
bytes,
using the key
.Fa key
of length
.Fa keylen .
.\"
.Pp
The
.Fn blake2s_init_param
and
.Fn blake2b_init_param
initialize a hash state
.Fa S
using a custom parameter block
.Fa P ,
which must have been filled in completely by the caller.
See the BLAKE2 paper and the
.In blake2.h
header file for details.
.\"
.Pp
The
.Fn blake2s_update ,
.Fn blake2b_update ,
.Fn blake2sp_update ,
and
.Fn blake2bp_update
functions hash the input buffer
.Fa in
of length
.Fa inlen
bytes into the hash state
.Fa S .
.\"
.Pp
The
.Fn blake2s_final ,
.Fn blake2b_final ,
.Fn blake2sp_final ,
and
.Fn blake2bp_final
functions compute the hash value accumulated in
.Fa S
and store it into
.Fa out .
.Fa outlen
must have the same value that was passed to
the corresponding init function.
.\"
.Pp
The
.Fn blake2s ,
.Fn blake2b ,
.Fn blake2sp ,
and
.Fn blake2bp
functions hash a single-buffer input in one function call,
optionally using a key.
.Pp
To use the latter functions without a key, set
.Fa keylen
to 0 and
.Fa key
to NULL.
.Pp
For all functions, the lengths
.Fa outlen ,
.Fa inlen ,
and
.Fa keylen
are specified in bytes.
.\"
.Pp
.Fa outlen
must be positive and no greater than
.Dv BLAKE2S_OUTBYTES
(32)
for the blake2s and blake2sp functions,
or positive and no greater than
.Dv BLAKE2B_OUTBYTES
(64)
for the blake2b and blake2bp functions.
.\"
.Pp
.Fa keylen
must be positive and no greater than
.Dv BLAKE2S_KEYBYTES
(32)
for the blake2s and blake2sp functions,
or positive and no greater than
.Dv BLAKE2B_KEYBYTES
(64)
for the blake2b and blake2bp functions.
.\"
.Sh RETURN VALUES
All of these functions return 0 if successful,
or -1 if they detect an error.
.Pp
All detected, reported errors are caused by
invalid pointer arguments
or out-of-bounds length arguments.
.Pp
Not all invalid arguments are detected.
.Pp
These functions do
.Em not
set
.Va errno
themselves,
but do call standard C library functions
which might set
.Va errno .
.\"
.Sh BUGS
The library does not include a self-test function.
.Pp
The library does not attempt to detect or report an error
if the caller exceeds the input length limits
specified for the BLAKE2 functions,
even for BLAKE2s and BLAKE2sp, whose length limits
(2**64-1 bytes and 2**67-1 bytes respectively)
could theoretically be reached.
.Pp
.Fn blake2s_final ,
.Fn blake2b_final ,
.Fn blake2sp_final ,
and
.Fn blake2bp_final
do not erase the state
.Fa S ,
and do not treat the hash value as sensitive,
even if they are used to compute a keyed hash.
.Pp
.Fn blake2s_final ,
.Fn blake2b_final ,
.Fn blake2sp_final ,
and
.Fn blake2bp_final
alter the state such that further calls
to the _update or _final functions
will produce poorly-behaved results,
and do not mark the state as no longer valid
in order to detect and prevent such programmer errors.