mirror of
https://github.com/RfidResearchGroup/proxmark3.git
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344 lines
9.8 KiB
C
344 lines
9.8 KiB
C
//-----------------------------------------------------------------------------
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// Copyright (C) 2010, Flavio D. Garcia, Peter van Rossum, Roel Verdult
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// and Ronny Wichers Schreur. Radboud University Nijmegen
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// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// See LICENSE.txt for the text of the license.
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//-----------------------------------------------------------------------------
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// SecureMemory, CryptoMemory and CryptoRF library
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//-----------------------------------------------------------------------------
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#include "cryptolib.h"
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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typedef enum {
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CA_ENCRYPT = 0x01,
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CA_DECRYPT = 0x02
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} CryptoAction;
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int counter = 0;
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static uint8_t nibbles_to_byte(nibble b0, nibble b1) {
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// Combine both nibbles
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return ((b0 << 4) | b1);
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}
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static uint8_t funny_mod(uint8_t a, uint8_t m) {
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// Just return the input when this is less or equal than the modular value
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if (a < m) return a;
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// Compute the modular value
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a %= m;
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// Return the funny value, when the output was now zero, return the modular value
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return (a == 0) ? m : a;
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}
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static uint8_t bit_rotate_left(uint8_t a, uint8_t n_bits) {
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// Rotate value a with the length of n_bits only 1 time
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uint8_t mask = (1 << n_bits) - 1;
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return ((a << 1) | (a >> (n_bits - 1))) & mask;
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}
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/*
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static void reconstruct_nibbles(crypto_state s)
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{
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uint8_t b1, b5, b8, b15, b18;
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uint8_t b0, b4, b7, b14, b17;
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// Extract the bytes that generated the "previous" nibble
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b1 = (uint8_t)((s->l >> 25) & 0x1f);
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b5 = (uint8_t)((s->l >> 5) & 0x1f);
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b8 = (uint8_t)((s->m >> 35) & 0x1f);
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b15 = (uint8_t)((s->r >> 15) & 0x1f);
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b18 = (uint8_t)(s->r & 0x1f);
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// Reconstruct the b0 nibble
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s->b0 = ((b1 ^ b5) & 0x0f) & ~(b8);
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s->b0 |= ((b15 ^ b18) & 0x0f) & b8;
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// Extract the bytes for the current nibble
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b0 = (uint8_t)((s->l >> 30) & 0x1f);
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b4 = (uint8_t)((s->l >> 10) & 0x1f);
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b7 = (uint8_t)((s->m >> 42) & 0x1f);
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b14 = (uint8_t)((s->r >> 20) & 0x1f);
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b17 = (uint8_t)((s->r >> 5) & 0x1f);
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// Construct the values for b1 generation
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s->b1l = ((b0 ^ b4) & 0x0f);
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s->b1r = ((b14 ^ b17) & 0x0f);
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s->b1s = b7;
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// Reconstruct the b1 nibble
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s->b1 = s->b1l & ~(s->b1s);
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s->b1 |= s->b1r & s->b1s;
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}
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*/
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static void next_left(uint8_t in, crypto_state s) {
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uint8_t b3, b6, bx;
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// Update the left cipher state with the input byte
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s->l ^= ((in & 0x1f) << 20);
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// Extract the two (5 bits) values used for modular addtion
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b3 = (uint8_t)((s->l >> 15) & 0x1f);
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b6 = (uint8_t)(s->l & 0x1f);
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// Compute the modular addition
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bx = funny_mod(b3 + bit_rotate_left(b6, 5), 0x1f);
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// Rotate the left cipher state 5 bits
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s->l = ((s->l >> 5) | ((uint64_t)bx << 30));
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// Save the 4 left output bits used for b1
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s->b1l = ((bx ^ b3) & 0x0f);
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}
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static void next_right(uint8_t in, crypto_state s) {
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uint8_t b16, b18, bx;
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// Update the right cipher state with the input byte
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s->r ^= ((in & 0xf8) << 12);
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// Extract the two (5 bits) values used for modular addtion
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b16 = (uint8_t)((s->r >> 10) & 0x1f);
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b18 = (uint8_t)(s->r & 0x1f);
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// Compute the modular addition
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bx = funny_mod(b18 + b16, 0x1f);
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// Rotate the right cipher state 5 bits
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s->r = ((s->r >> 5) | ((uint64_t)bx << 20));
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// Save the 4 right output bits used for b1
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s->b1r = ((bx ^ b16) & 0x0f);
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}
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static void next_middle(uint8_t in, crypto_state s) {
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uint8_t b12, b13, bx;
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// Update the middle cipher state with the input byte
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s->m ^= (((((uint64_t)in << 3) & 0x7f) | (in >> 5)) << 14);
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// Extract the two (7 bits) values used for modular addtion
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b12 = (uint8_t)((s->m >> 7) & 0x7f);
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b13 = (uint8_t)(s->m & 0x7f);
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// Compute the modular addition
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bx = (funny_mod(b12 + bit_rotate_left(b13, 7), 0x7f));
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// Rotate the middle cipher state 7 bits
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s->m = ((s->m >> 7) | ((uint64_t)bx << 42));
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// Save the 4 middle selector bits used for b1
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s->b1s = bx & 0x0f;
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}
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static void next(const bool feedback, uint8_t in, crypto_state s) {
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// Initialize the (optional) input parameter
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uint8_t a = in;
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// Only Cryptomemory uses feedback
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if (feedback) {
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// Construct the cipher update 'a' from (input ^ feedback)
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a = in ^ nibbles_to_byte(s->b0, s->b1);
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}
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// Shift the cipher state
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next_left(a, s);
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next_middle(a, s);
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next_right(a, s);
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// For active states we can use the available (previous) 'b1' nibble,
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// otherwise use reconstruct_nibbles() to generate them
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// reconstruct_nibbles(s)
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// The nible from b1 shifts to b0
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s->b0 = s->b1;
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// Construct the new value of nible b1
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s->b1 = s->b1l & ~(s->b1s);
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s->b1 |= s->b1r & s->b1s;
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}
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static void next_n(const bool feedback, size_t n, uint8_t in, crypto_state s) {
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// While n-rounds left, shift the cipher
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while (n--) next(feedback, in, s);
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}
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static void initialize(const bool feedback, const uint8_t *Gc, const uint8_t *Ci, const uint8_t *Q, const size_t n, crypto_state s) {
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size_t pos;
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// Reset the cipher state
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memset(s, 0x00, sizeof(crypto_state_t));
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// Load in the ci (tag-nonce), together with the first half of Q (reader-nonce)
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for (pos = 0; pos < 4; pos++) {
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next_n(feedback, n, Ci[2 * pos ], s);
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next_n(feedback, n, Ci[2 * pos + 1], s);
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next(feedback, Q[pos], s);
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}
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// Load in the diversified key (Gc), together with the second half of Q (reader-nonce)
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for (pos = 0; pos < 4; pos++) {
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next_n(feedback, n, Gc[2 * pos ], s);
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next_n(feedback, n, Gc[2 * pos + 1], s);
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next(feedback, Q[pos + 4], s);
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}
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}
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static uint8_t cm_byte(crypto_state s) {
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// Construct keystream byte by combining both nibbles
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return nibbles_to_byte(s->b0, s->b1);
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}
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static uint8_t sm_byte(crypto_state s) {
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uint8_t ks;
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// Construct keystream byte by combining 2 parts from 4 nibbles
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next_n(false, 2, 0, s);
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ks = s->b1 << 4;
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next_n(false, 2, 0, s);
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ks |= s->b1;
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return ks;
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}
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void print_crypto_state(const char *text, crypto_state s) {
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int pos;
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printf("%s", text);
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for (pos = 6; pos >= 0; pos--)
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printf(" %02x", (uint8_t)(s->l >> (pos * 5)) & 0x1f);
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printf(" |");
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for (pos = 6; pos >= 0; pos--)
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printf(" %02x", (uint8_t)(s->m >> (pos * 7)) & 0x7f);
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printf(" |");
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for (pos = 4; pos >= 0; pos--)
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printf(" %02x", (uint8_t)(s->r >> (pos * 5)) & 0x1f);
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printf(" | %02x", cm_byte(s));
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printf("\n");
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}
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void sm_auth(const uint8_t *Gc, const uint8_t *Ci, const uint8_t *Q, uint8_t *Ch, uint8_t *Ci_1, crypto_state s) {
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size_t pos;
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initialize(false, Gc, Ci, Q, 1, s);
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// Generate challenge answer for Tag and Reader
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for (pos = 0; pos < 8; pos++) {
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Ci_1[pos] = sm_byte(s);
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Ch[pos] = sm_byte(s);
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}
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}
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void cm_auth(const uint8_t *Gc, const uint8_t *Ci, const uint8_t *Q, uint8_t *Ch, uint8_t *Ci_1, uint8_t *Ci_2, crypto_state s) {
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size_t pos;
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initialize(true, Gc, Ci, Q, 3, s);
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// Construct the reader-answer (challenge)
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next_n(true, 6, 0, s);
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Ch[0] = cm_byte(s);
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for (pos = 1; pos < 8; pos++) {
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next_n(true, 7, 0, s);
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Ch [pos] = cm_byte(s);
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}
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// Construct the tag-answer (Ci+1 = ff .. .. .. .. .. .. ..)
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Ci_1[0] = 0xff;
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for (pos = 1; pos < 8; pos++) {
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next_n(true, 2, 0, s);
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Ci_1[pos] = cm_byte(s);
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}
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// Construct the session key (Ci+2)
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for (pos = 0; pos < 8; pos++) {
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next_n(true, 2, 0, s);
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Ci_2[pos] = cm_byte(s);
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}
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// Prepare the cipher for encryption by shifting 3 more times
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next_n(true, 3, 0, s);
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}
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static void cm_crypt(const CryptoAction ca, const uint8_t offset, const uint8_t len, const uint8_t *in, uint8_t *out, crypto_state s) {
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size_t pos;
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uint8_t bt;
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next_n(true, 5, 0, s);
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next(true, offset, s);
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next_n(true, 5, 0, s);
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next(true, len, s);
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for (pos = 0; pos < len; pos++) {
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// Perform the crypto operation
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bt = in[pos] ^ cm_byte(s);
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// Generate output
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if (out) out[pos] = bt;
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// Detect where to find the plaintext for loading into cipher state
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if (ca == CA_DECRYPT) {
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next(true, bt, s);
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} else {
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next(true, in[pos], s);
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}
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// Shift the cipher state 5 times
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next_n(true, 5, 0, s);
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}
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}
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void cm_encrypt(const uint8_t offset, const uint8_t len, const uint8_t *pt, uint8_t *ct, crypto_state s) {
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next_n(true, 5, 0, s);
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next(true, 0, s);
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cm_crypt(CA_ENCRYPT, offset, len, pt, ct, s);
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}
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void cm_decrypt(const uint8_t offset, const uint8_t len, const uint8_t *ct, uint8_t *pt, crypto_state s) {
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next_n(true, 5, 0, s);
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next(true, 0, s);
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cm_crypt(CA_DECRYPT, offset, len, ct, pt, s);
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}
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void cm_grind_read_system_zone(const uint8_t offset, const uint8_t len, const uint8_t *pt, crypto_state s) {
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cm_crypt(CA_ENCRYPT, offset, len, pt, NULL, s);
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}
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void cm_grind_set_user_zone(const uint8_t zone, crypto_state s) {
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next(true, zone, s);
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}
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void cm_mac(uint8_t *mac, crypto_state s) {
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next_n(true, 10, 0, s);
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if (mac)
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mac[0] = cm_byte(s);
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next_n(true, 5, 0, s);
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if (mac)
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mac[1] = cm_byte(s);
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}
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void cm_password(const uint8_t *pt, uint8_t *ct, crypto_state s) {
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for (size_t pos = 0; pos < 3; pos++) {
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next_n(true, 5, pt[pos], s);
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ct[pos] = cm_byte(s);
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}
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}
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