139 lines
4.1 KiB
C
139 lines
4.1 KiB
C
// SPDX-FileCopyrightText: 1995 Tatu Ylonen <ylo@cs.hut.fi>
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// SPDX-FileCopyrightText: 2000, 2001 Markus Friedl
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// SPDX-License-Identifier: BSD-2-Clause
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/*
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* This code is originally taken from OpenSSH:
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* http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/key.c?rev=1.75&content-type=text/x-cvsweb-markup
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*/
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/*
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* Draw an ASCII-Art representing the fingerprint so human brain can
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* profit from its built-in pattern recognition ability.
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* This technique is called "random art" and can be found in some
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* scientific publications like this original paper:
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*
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* "Hash Visualization: a New Technique to improve Real-World Security",
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* Perrig A. and Song D., 1999, International Workshop on Cryptographic
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* Techniques and E-Commerce (CrypTEC '99)
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* sparrow.ece.cmu.edu/~adrian/projects/validation/validation.pdf
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*
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* The subject came up in a talk by Dan Kaminsky, too.
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*
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* If you see the picture is different, the key is different.
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* If the picture looks the same, you still know nothing.
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*
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* The algorithm used here is a worm crawling over a discrete plane,
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* leaving a trace (augmenting the field) everywhere it goes.
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* Movement is taken from buffer 2bit-wise. Bumping into walls
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* makes the respective movement vector be ignored for this turn.
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* Graphs are not unambiguous, because circles in graphs can be
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* walked in either direction.
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*/
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/*
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* Field sizes for the random art. Have to be odd, so the starting point
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* can be in the exact middle of the picture, and FLDBASE should be >=8 .
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* Else pictures would be too dense, and drawing the frame would
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* fail, too, because the key type would not fit in anymore.
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*/
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#include <rz_hash.h>
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#include <rz_util.h>
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#define FLDBASE 8
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#define FLDSIZE_Y (FLDBASE + 1)
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#define FLDSIZE_X (FLDBASE * 2 + 1)
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/**
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* \brief Generates a randomart that is meant to be an easily validate buffers.
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*
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* \param buffer The buffer to use to generate the
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* \param length The buffer length
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* \param addr The location of the hash (when unknown can be set to 0).
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* \return
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*/
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RZ_API RZ_OWN char *rz_hash_cfg_randomart(RZ_NONNULL const ut8 *buffer, ut32 length, ut64 address) {
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rz_return_val_if_fail(buffer && length > 0, NULL);
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/*
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* Chars to be used after each other every time the worm
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* intersects with itself. Matter of taste.
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*/
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char *augmentation_string = " .o+=*BOX@%&#/^SE";
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char *retval, *p;
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ut8 field[FLDSIZE_X][FLDSIZE_Y];
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ut32 i, b;
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int x, y;
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size_t len = strlen(augmentation_string) - 1;
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// 2*(FLDSIZE_X+3) there are two for loops that iterate over this
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// FLDSIZE_Y * (FLDSIZE_X+3) there is a loop that for each y iterates over the whole FLDSIZE_X
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// The rest is counting the +--[0x%08"PFMT64x"]- and '\0'
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retval = calloc(1, 2 * (FLDSIZE_X + 3) + (FLDSIZE_Y * (FLDSIZE_X + 3)) + 7 + sizeof(PFMT64x));
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if (!retval) {
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return NULL;
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}
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/* initialize field */
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memset(field, 0, FLDSIZE_X * FLDSIZE_Y * sizeof(char));
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x = FLDSIZE_X / 2;
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y = FLDSIZE_Y / 2;
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/* process raw key */
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for (i = 0; i < length; i++) {
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int input;
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/* each byte conveys four 2-bit move commands */
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input = buffer[i];
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for (b = 0; b < 4; b++) {
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/* evaluate 2 bit, rest is shifted later */
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x += (input & 0x1) ? 1 : -1;
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y += (input & 0x2) ? 1 : -1;
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/* assure we are still in bounds */
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x = RZ_MAX(x, 0);
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y = RZ_MAX(y, 0);
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x = RZ_MIN(x, FLDSIZE_X - 1);
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y = RZ_MIN(y, FLDSIZE_Y - 1);
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/* augment the field */
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if (field[x][y] < len - 2) {
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field[x][y]++;
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}
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input = input >> 2;
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}
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}
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/* mark starting point and end point*/
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field[FLDSIZE_X / 2][FLDSIZE_Y / 2] = len - 1;
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field[x][y] = len;
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/* fill in retval */
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sprintf(retval, "+--[0x%08" PFMT64x "]-", address);
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p = strchr(retval, '\0');
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/* output upper border */
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for (i = p - retval - 1; i < FLDSIZE_X; i++) {
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*p++ = '-';
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}
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*p++ = '+';
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*p++ = '\n';
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/* output content */
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for (y = 0; y < FLDSIZE_Y; y++) {
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*p++ = '|';
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for (x = 0; x < FLDSIZE_X; x++) {
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*p++ = augmentation_string[RZ_MIN(field[x][y], len)];
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}
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*p++ = '|';
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*p++ = '\n';
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}
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/* output lower border */
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*p++ = '+';
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for (i = 0; i < FLDSIZE_X; i++) {
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*p++ = '-';
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}
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*p++ = '+';
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*p++ = 0;
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return retval;
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}
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