77 lines
1.3 KiB
ArmAsm
77 lines
1.3 KiB
ArmAsm
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bits 64
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global _start
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_start:
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push rbp
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push rsp
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push rbx
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push r13
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push rax
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push rcx
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push rdx
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push rsi
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push rdi
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push r8
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push r9
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mov rdi, 1
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lea rsi, [rel msg]
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mov rbx, rsi
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;mov rbx, qword [rel text_section]
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sub rbx, qword [rel text_section] ;text_section address because of this and that
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mov r8, qword [rel section_size] ;text_section size
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mov r9, 0 ;increment register
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xor r13, r13
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mov r13, qword [rel private_key]
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decrypt_whole_blocks:
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; check left to decrypt < block_size
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mov rcx, r8
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sub rcx, r9
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cmp rcx, 8
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jle decrypt_last_block
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; xor section with private_key
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mov rdx, rbx
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add rdx, r9
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xor [rdx], r13
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; increase section address
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; increase counter
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add r9, 8
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jmp decrypt_whole_blocks
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decrypt_last_block:
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mov rdx, 8
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sub rdx, rcx
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mov rcx, rdx
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mov rax, 8
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mul cl
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mov rcx, rax
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shl r13, cl
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shr r13, cl
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mov rdx, rbx
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add rdx, r9
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xor [rdx], r13
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end_decrypt:
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mov rdx, 14
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mov rax, 1
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syscall
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pop r9
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pop r8
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pop rdi
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pop rsi
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pop rdx
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pop rcx
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pop rax
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pop r13
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pop rbx
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pop rsp
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pop rbp
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jmp 0xdadadada ; this needs to be just before that
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msg db "....WOODY....",10 ; that needs to be just after this
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text_section dq 0xbabababababababa
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section_size dq 0xcacacacacacacaca
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private_key dq 0xabcdefabcdefabcd
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