From 3e1864aa14a33a3c917537a241f6a032cfcacf78 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sat, 14 Oct 2017 01:01:14 +0200 Subject: General improvements MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- man/libkeccak_fast_digest.3 | 146 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 146 insertions(+) create mode 100644 man/libkeccak_fast_digest.3 (limited to 'man/libkeccak_fast_digest.3') diff --git a/man/libkeccak_fast_digest.3 b/man/libkeccak_fast_digest.3 new file mode 100644 index 0000000..d5c55a5 --- /dev/null +++ b/man/libkeccak_fast_digest.3 @@ -0,0 +1,146 @@ +.TH LIBKECCAK_FAST_DIGEST 3 LIBKECCAK +.SH NAME +libkeccak_fast_digest - Complete the hashing of a message without erasure +.SH SYNOPSIS +.LP +.nf +#include +.P +int +libkeccak_fast_digest(libkeccak_state_t *\fIstate\fP, const char *\fImsg\fP, + size_t \fImsglen\fP, size_t \fIbits\fP, const char *\fIsuffix\fP, + char *\fIhashsum\fP); +.fi +.P +Link with +.IR -lkeccak . +.SH DESCRIPTION +The +.BR libkeccak_fast_digest () +function absorbs the last part of (or all of) a message, +and returns the hash of the entire message. The last part +of the message is specified by the +.I msg +parameter, and its byte-size is specified by the +.I msglen +parameter. If all of the message has already be processed +by calls to the +.BR libkeccak_update (3) +function or the +.BR libkeccak_fast_update (3) +function (with the same pointer on +.IR state ,) +.I msg +and +.I msglen +should be set to +.I NULL +and 0, respectively. +.PP +If the message is not comprised a whole number of bytes, +the number of bits, modulus 8, in the message should be +specified in the +.I bits +parameter. +.I msglen +must only count the number of whole bytes, that is, the +floor of the number of bits in the message divided by 8. +.PP +.I suffix +should be a NUL-terminated string of ASCII '1':s and '0':s, +representing the bits that should be appended to the +message. If this string is empty, +.I NULL +may be used instead. This is used to select hash algorithm. +For pure Keccak, +.I NULL +or "" is used. For the other algorithms the constants +.B LIBKECCAK_SHA3_SUFFIX +(for SHA-3), +.B LIBKECCAK_RAWSHAKE_SUFFIX +(for RawSHAKE), and +.B LIBKECCAK_SHAKE_SUFFIX +(for SHAKE) are used. +.PP +The hash of the message will be stored to +.IR hashsum , +unless +.IR hashsum +is +.IR NULL +(which increases the performance of the call.) A total of +.RI (( state->n ++ 7) / 8) bytes will be written to the beginning of +.IR hashsum . +Therefore, +.I hashsum +needs at least an allocation size of that number of bytes. +.PP +The +.BR libkeccak_fast_digest () +function may reallocate the state's message chunk buffer. +When doing so, it attempts to do so as quickly as possible, +rather than ensuring that the information in the old +allocation is securely removed if a new allocation is required. +.SH RETURN VALUES +The +.BR libkeccak_fast_digest () +function returns 0 upon successful completion. On error, +-1 is returned and +.I errno +is set to describe the error. +.SH ERRORS +The +.BR libkeccak_fast_digest () +function may fail for any reason specified by the function +.BR realloc (3). +.SH EXAMPLE +This example calculates the Keccak[b = 1024, c = 576, n = 256] +hash of the input from stdin, and prints the hash, in hexadecimal +form, to stdout. +.LP +.nf +libkeccak_state_t state; +libkeccak_spec_t spec; +char binhash[256 / 8]; +char hexhash[256 / 8 * 2 + 1]; +char chunk[4 << 10]; +ssize_t len; + +spec.bitrate = 1024; +spec.capacity = 576; +spec.output = 256; +if (libkeccak_state_initialise(&state, &spec) < 0) + goto fail; + +for (;;) { + len = read(STDIN_FILENO, chunk, sizeof(chunk)); + + if ((len < 0) && (errno == EINTR)) + continue; + if (len < 0) + goto fail; + if (len == 0) + break; + + if (libkeccak_fast_update(&state, chunk, (size_t)len) < 0) + goto fail; +} +if (libkeccak_fast_digest(&state, NULL, 0, 0, "", binhash) < 0) + goto fail; + +libkeccak_behex_lower(hexhash, binhash, sizeof(binhash)); +printf("%s\\n", hexhash); +libkeccak_state_fast_destroy(&state); +.fi +.SH SEE ALSO +.BR libkeccak_state_initialise (3), +.BR libkeccak_fast_update (3), +.BR libkeccak_update (3), +.BR libkeccak_digest (3), +.BR libkeccak_simple_squeeze (3), +.BR libkeccak_fast_squeeze (3), +.BR libkeccak_squeeze (3) +.SH BUGS +Please report bugs to https://github.com/maandree/libkeccak/issues or to +maandree@kth.se -- cgit v1.2.3-70-g09d2