extern puts
extern printf

section .data
filename: db "/home/cami/Anul2/IOCLA/Tema2/iocla-tema2-resurse/input.dat",0
inputlen: dd 2263
fmtstr: db "Key: %d",0xa,0



    print db "strlen('') = %d", 10, 0

section .text
global main

; TODO: define functions and helper functions
xor_strings:
    push ebp
    mov ebp, esp

    xor eax, eax
    xor ebx, ebx
    mov eax, [ebp + 16] ;mesajul
    mov ebx, [ebp + 12] ;cheia
    mov edx, [ebp + 8] ;lungimea
    xor ecx, ecx

    push edx
        push print
        call printf
    decode_xor_strings:
        xor ecx, ecx
        mov ecx, [ebx + edx - 1]
        mov eax, [eax + edx - 1]

        xor eax, ecx

        dec edx
        cmp edx, 0
        jg decode_xor_strings

    leave
    ret

strlen:
   push ebp
   mov ebp, esp
    xor eax, eax
    cld
    mov al, 0
    mov edi,[ebp + 8]
    repne scasb
    sub edi, [ebp + 8]
    dec edi
    mov eax, edi
    leave
    ret

main:
    push ebp
    mov ebp, esp
    sub esp, 2300

    ; fd = open("/home/cami/Anul2/IOCLA/Tema2/iocla-tema2-resurse/input.dat", O_RDONLY);
    mov eax, 5
    mov ebx, filename
    xor ecx, ecx
    xor edx, edx
    int 0x80

    ; read(fd, ebp-2300, inputlen);
    mov ebx, eax
    mov eax, 3
    lea ecx, [ebp-2300]
    mov edx, [inputlen]
    int 0x80

    ; close(fd);
    mov eax, 6
    int 0x80

        xor edx, edx
    ; all input.dat contents are now in ecx (address on stack)

    ; TASK 1: Simple XOR between two byte streams
    ; TODO: compute addresses on stack for str1 and str2
    ; TODO: XOR them byte by byte


        push ecx
        call strlen
        add esp, 4

        add edx, eax

        push ecx ;mesajul
        lea ecx, [ecx + edx + 1]


        add esp, 8
        push ecx ;cheia
        push edx ;lungimea mesajului

       ; add edx, eax ;pozitia curenta
       ; add edx, 2
       ; xor eax, eax

        call xor_strings

        add esp, 12


       ;push eax
       ;call puts
       ;add esp, 4


    ;push addr_str2
    ;push addr_str1
    ;call xor_strings
    ;add esp, 8

    ; Print the first resulting string
    ;push addr_str1
    ;call puts
    ;add esp, 4

    ; TASK 2: Rolling XOR
    ; TODO: compute address on stack for str3
    ; TODO: implement and apply rolling_xor function
    ;push addr_str3
    ;call rolling_xor
    ;add esp, 4

    ; Print the second resulting string
    ;push addr_str3
    ;call puts
    ;add esp, 4


    ; TASK 3: XORing strings represented as hex strings
    ; TODO: compute addresses on stack for strings 4 and 5
    ; TODO: implement and apply xor_hex_strings
    ;push addr_str5
    ;push addr_str4
    ;call xor_hex_strings
    ;add esp, 8

    ; Print the third string
    ;push addr_str4
    ;call puts
    ;add esp, 4

    ; TASK 4: decoding a base32-encoded string
    ; TODO: compute address on stack for string 6
    ; TODO: implement and apply base32decode
    ;push addr_str6
    ;call base32decode
    ;add esp, 4

    ; Print the fourth string
    ;push addr_str6
    ;call puts
    ;add esp, 4

    ; TASK 5: Find the single-byte key used in a XOR encoding
    ; TODO: determine address on stack for string 7
    ; TODO: implement and apply bruteforce_singlebyte_xor
    ;push key_addr
    ;push addr_str7
    ;call bruteforce_singlebyte_xor
    ;add esp, 8

    ; Print the fifth string and the found key value
    ;push addr_str7
    ;call puts
    ;add esp, 4

    ;push keyvalue
    ;push fmtstr
    ;call printf
    ;add esp, 8

    ; TASK 6: Break substitution cipher
    ; TODO: determine address on stack for string 8
    ; TODO: implement break_substitution
    ;push substitution_table_addr
    ;push addr_str8
    ;call break_substitution
    ;add esp, 8

    ; Print final solution (after some trial and error)
    ;push addr_str8
    ;call puts
    ;add esp, 4

    ; Print substitution table
    ;push substitution_table_addr
    ;call puts
    ;add esp, 4

    ; Phew, finally done
    xor eax, eax
    leave
    ret