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Diffstat (limited to 'lib/extras/randomart.c')
| -rw-r--r-- | lib/extras/randomart.c | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/lib/extras/randomart.c b/lib/extras/randomart.c new file mode 100644 index 0000000..cfd7e1c --- /dev/null +++ b/lib/extras/randomart.c @@ -0,0 +1,172 @@ +/* $OpenBSD: key.c,v 1.98 2011/10/18 04:58:26 djm Exp $ */ +/* + * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. + * Copyright (c) 2008 Alexander von Gernler. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "gnutls_int.h" +#include "errors.h" +#include <randomart.h> + +/* + * Draw an ASCII-Art representing the fingerprint so human brain can + * profit from its built-in pattern recognition ability. + * This technique is called "random art" and can be found in some + * scientific publications like this original paper: + * + * "Hash Visualization: a New Technique to improve Real-World Security", + * Perrig A. and Song D., 1999, International Workshop on Cryptographic + * Techniques and E-Commerce (CrypTEC '99) + * sparrow.ece.cmu.edu/~adrian/projects/validation/validation.pdf + * + * The subject came up in a talk by Dan Kaminsky, too. + * + * If you see the picture is different, the key is different. + * If the picture looks the same, you still know nothing. + * + * The algorithm used here is a worm crawling over a discrete plane, + * leaving a trace (augmenting the field) everywhere it goes. + * Movement is taken from dgst_raw 2bit-wise. Bumping into walls + * makes the respective movement vector be ignored for this turn. + * Graphs are not unambiguous, because circles in graphs can be + * walked in either direction. + */ + +/* + * Field sizes for the random art. Have to be odd, so the starting point + * can be in the exact middle of the picture, and FLDBASE should be >=8 . + * Else pictures would be too dense, and drawing the frame would + * fail, too, because the key type would not fit in anymore. + */ +#define FLDBASE 8 +#define FLDSIZE_Y (FLDBASE + 1) +#define FLDSIZE_X (FLDBASE * 2 + 1) +char *_gnutls_key_fingerprint_randomart(uint8_t * dgst_raw, + u_int dgst_raw_len, + const char *key_type, + unsigned int key_size, + const char *prefix) +{ + /* + * Chars to be used after each other every time the worm + * intersects with itself. Matter of taste. + */ + const char augmentation_string[] = " .o+=*BOX@%&#/^SE"; + char *retval, *p; + uint8_t field[FLDSIZE_X][FLDSIZE_Y]; + char size_txt[16]; + unsigned int i, b; + int x, y; + const size_t len = sizeof(augmentation_string) - 2; + unsigned int prefix_len = 0; + + if (prefix) + prefix_len = strlen(prefix); + + retval = + gnutls_calloc(1, + (FLDSIZE_X + 3 + prefix_len) * (FLDSIZE_Y + 2)); + if (retval == NULL) { + gnutls_assert(); + return NULL; + } + + /* initialize field */ + memset(field, 0, FLDSIZE_X * FLDSIZE_Y * sizeof(char)); + x = FLDSIZE_X / 2; + y = FLDSIZE_Y / 2; + + /* process raw key */ + for (i = 0; i < dgst_raw_len; i++) { + int input; + /* each byte conveys four 2-bit move commands */ + input = dgst_raw[i]; + for (b = 0; b < 4; b++) { + /* evaluate 2 bit, rest is shifted later */ + x += (input & 0x1) ? 1 : -1; + y += (input & 0x2) ? 1 : -1; + + /* assure we are still in bounds */ + x = MAX(x, 0); + y = MAX(y, 0); + x = MIN(x, FLDSIZE_X - 1); + y = MIN(y, FLDSIZE_Y - 1); + + /* augment the field */ + if (field[x][y] < len - 2) + field[x][y]++; + input = input >> 2; + } + } + + /* mark starting point and end point */ + field[FLDSIZE_X / 2][FLDSIZE_Y / 2] = len - 1; + field[x][y] = len; + + if (key_size > 0) + snprintf(size_txt, sizeof(size_txt), " %4u", key_size); + else + size_txt[0] = 0; + + /* fill in retval */ + if (prefix_len) + snprintf(retval, FLDSIZE_X + prefix_len, "%s+--[%4s%s]", + prefix, key_type, size_txt); + else + snprintf(retval, FLDSIZE_X, "+--[%4s%s]", key_type, + size_txt); + p = strchr(retval, '\0'); + + /* output upper border */ + for (i = p - retval - 1; i < FLDSIZE_X + prefix_len; i++) + *p++ = '-'; + *p++ = '+'; + *p++ = '\n'; + + if (prefix_len) { + memcpy(p, prefix, prefix_len); + p += prefix_len; + } + + /* output content */ + for (y = 0; y < FLDSIZE_Y; y++) { + *p++ = '|'; + for (x = 0; x < FLDSIZE_X; x++) + *p++ = augmentation_string[MIN(field[x][y], len)]; + *p++ = '|'; + *p++ = '\n'; + + if (prefix_len) { + memcpy(p, prefix, prefix_len); + p += prefix_len; + } + } + + /* output lower border */ + *p++ = '+'; + for (i = 0; i < FLDSIZE_X; i++) + *p++ = '-'; + *p++ = '+'; + + return retval; +} |