AES DFA

check_faults.c

bool check_faults(uint8_t *ct, uint8_t *expected_ct) {
    bool good_fault;

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 1 || i == 8 || i == 11 || i == 14) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 2 || i == 5 || i == 12 || i == 15) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 3 || i == 6 || i == 9 || i == 16) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 4 || i == 7 || i == 10 || i == 13) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 1 || i == 6 || i == 11 || i == 16) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 2 || i == 7 || i == 12 || i == 13) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 3 || i == 8 || i == 9 || i == 14) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    good_fault = true;
    for (int i = 1; i <= 16; i++) {
        if (i == 4 || i == 5 || i == 10 || i == 15) {
            if (ct[i] == expected_ct[i]) {
                good_fault = false;
            }
        } else {
            if (ct[i] != expected_ct[i]) {
                good_fault = false;
            }
        }
    }
    if (good_fault) {
        return true;
    }

    return false;
}

dfadiff.py

#! env python

import sys


def check_faults(ct, expected_ct):
    good_fault = True
    for i in range(0, 16):
        if i + 1 in [1, 8, 11, 14]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [2, 5, 12, 15]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [3, 6, 9, 16]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [4, 7, 10, 13]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [1, 6, 11, 16]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [2, 7, 12, 13]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [3, 8, 9, 14]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    good_fault = True
    for i in range(0, 16):
        if i + 1 in [4, 5, 10, 15]:
            if ct[i] == expected_ct[i]:
                good_fault = False
        else:
            if ct[i] != expected_ct[i]:
                good_fault = False
    if good_fault:
        return True

    return False


def diff(ct, expected_ct):
    d = str()
    for i in range(16):
        if i != 0 and i % 4 == 0:
            d += ' '

        if ct[i] == expected_ct[i]:
            d += '*'
        else:
            d += '.'
    return d


def main():
    expected_ct = bytes.fromhex(sys.argv[1])

    line = sys.stdin.readline()
    while line is not None:
        line = line.strip('\n')
        if line == '':
            break

        ct = bytes.fromhex(line)
        if check_faults(ct, expected_ct):
            print('[y] ', end='')
        else:
            print('[n] ', end='')
        print(expected_ct.hex(), line, diff(ct, expected_ct))
        sys.stdout.flush()
        line = sys.stdin.readline()


if __name__ == '__main__':
    main()