+
+ /* Remove the trailing ':' character */
+ retval[(dgst_raw_len * 3) - 1] = '\0';
+ return retval;
+}
+
+static char *
+key_fingerprint_bubblebabble(u_char *dgst_raw, u_int dgst_raw_len)
+{
+ char vowels[] = { 'a', 'e', 'i', 'o', 'u', 'y' };
+ char consonants[] = { 'b', 'c', 'd', 'f', 'g', 'h', 'k', 'l', 'm',
+ 'n', 'p', 'r', 's', 't', 'v', 'z', 'x' };
+ u_int i, j = 0, rounds, seed = 1;
+ char *retval;
+
+ rounds = (dgst_raw_len / 2) + 1;
+ retval = xcalloc((rounds * 6), sizeof(char));
+ retval[j++] = 'x';
+ for (i = 0; i < rounds; i++) {
+ u_int idx0, idx1, idx2, idx3, idx4;
+ if ((i + 1 < rounds) || (dgst_raw_len % 2 != 0)) {
+ idx0 = (((((u_int)(dgst_raw[2 * i])) >> 6) & 3) +
+ seed) % 6;
+ idx1 = (((u_int)(dgst_raw[2 * i])) >> 2) & 15;
+ idx2 = ((((u_int)(dgst_raw[2 * i])) & 3) +
+ (seed / 6)) % 6;
+ retval[j++] = vowels[idx0];
+ retval[j++] = consonants[idx1];
+ retval[j++] = vowels[idx2];
+ if ((i + 1) < rounds) {
+ idx3 = (((u_int)(dgst_raw[(2 * i) + 1])) >> 4) & 15;
+ idx4 = (((u_int)(dgst_raw[(2 * i) + 1]))) & 15;
+ retval[j++] = consonants[idx3];
+ retval[j++] = '-';
+ retval[j++] = consonants[idx4];
+ seed = ((seed * 5) +
+ ((((u_int)(dgst_raw[2 * i])) * 7) +
+ ((u_int)(dgst_raw[(2 * i) + 1])))) % 36;
+ }
+ } else {
+ idx0 = seed % 6;
+ idx1 = 16;
+ idx2 = seed / 6;
+ retval[j++] = vowels[idx0];
+ retval[j++] = consonants[idx1];
+ retval[j++] = vowels[idx2];
+ }
+ }
+ retval[j++] = 'x';
+ retval[j++] = '\0';
+ return retval;
+}
+
+/*
+ * 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)
+static char *
+key_fingerprint_randomart(u_char *dgst_raw, u_int dgst_raw_len, const Key *k)
+{
+ /*
+ * Chars to be used after each other every time the worm
+ * intersects with itself. Matter of taste.
+ */
+ char *augmentation_string = " .o+=*BOX@%&#/^SE";
+ char *retval, *p;
+ u_char field[FLDSIZE_X][FLDSIZE_Y];
+ u_int i, b;
+ int x, y;
+ size_t len = strlen(augmentation_string) - 1;
+
+ retval = xcalloc(1, (FLDSIZE_X + 3) * (FLDSIZE_Y + 2));
+
+ /* 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;
+
+ /* fill in retval */
+ snprintf(retval, FLDSIZE_X, "+--[%4s %4u]", key_type(k), key_size(k));
+ p = strchr(retval, '\0');
+
+ /* output upper border */
+ for (i = p - retval - 1; i < FLDSIZE_X; i++)
+ *p++ = '-';
+ *p++ = '+';
+ *p++ = '\n';
+
+ /* 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';
+ }
+
+ /* output lower border */
+ *p++ = '+';
+ for (i = 0; i < FLDSIZE_X; i++)
+ *p++ = '-';
+ *p++ = '+';
+
+ return retval;
+}
+
+char *
+key_fingerprint(const Key *k, enum fp_type dgst_type, enum fp_rep dgst_rep)
+{
+ char *retval = NULL;
+ u_char *dgst_raw;
+ u_int dgst_raw_len;
+
+ dgst_raw = key_fingerprint_raw(k, dgst_type, &dgst_raw_len);
+ if (!dgst_raw)
+ fatal("key_fingerprint: null from key_fingerprint_raw()");
+ switch (dgst_rep) {
+ case SSH_FP_HEX:
+ retval = key_fingerprint_hex(dgst_raw, dgst_raw_len);
+ break;
+ case SSH_FP_BUBBLEBABBLE:
+ retval = key_fingerprint_bubblebabble(dgst_raw, dgst_raw_len);
+ break;
+ case SSH_FP_RANDOMART:
+ retval = key_fingerprint_randomart(dgst_raw, dgst_raw_len, k);
+ break;
+ default:
+ fatal("key_fingerprint: bad digest representation %d",
+ dgst_rep);
+ break;
+ }
+ memset(dgst_raw, 0, dgst_raw_len);
+ xfree(dgst_raw);