capa-rules/lib/validate-payment-card-number-using-luhn-algorithm-with-no-lookup-table.yml

rule:
  meta:
    name: validate payment card number using luhn algorithm with no lookup table
    authors:
      - "@_re_fox"
    lib: true
    scopes:
      static: function
      dynamic: unsupported  # requires characteristic, offset, mnemonic features
    mbc:
      - Data::Checksum::Luhn [C0032.002]
    examples:
      - 6fcc13563aad936c7d0f3165351cb453:0x4026C0
  features:
    - and:
      - characteristic: loop
        description: Iterate over CC digits
      - or:
        - basic block:
          - and:
            # 6fcc13563aad936c7d0f3165351cb453:402842
            - or:
              - instruction:
                - mnemonic: shl
                - number: 0x1
              - instruction:
                - mnemonic: imul
                - number: 0x2
              - mnemonic: add = add al, al
            - instruction:
              - mnemonic: cmp
              - number: 0x9
            - description: Digital Root check number*2 < 0x9
        - and:
          - instruction:
            - mnemonic: cmp
            - number: 0x9
            - description: Compare number to 0x9 for Digital Root
          - basic block:
            - or:
              - instruction:
                - mnemonic: imul
                - number: 0x2
              - instruction:
                - mnemonic: shl
                - number: 0x1
              - mnemonic: add = add al, al
              - description: 2*Number for Digital Root
      - or:
        - instruction:
          # 6fcc13563aad936c7d0f3165351cb453:0x402820
          - mnemonic: sub
          - number: 0x30
          - description: Conversion of chr to int (SUB 0x30)
        - instruction:
          - offset: -0x30
          - mnemonic: lea
          - description: Conversion of chr to int (LEA REG,[REG+ -0x30])
      - basic block:
        - or:
          - and:
            # 6fcc13563aad936c7d0f3165351cb453:0x402857
            - or:
              - mnemonic: div
              - and:
                - mnemonic: idiv
                - mnemonic: cdq
            - number: 0xa
            - optional:
              - mnemonic: neg
            - description: Final section returning checkum % 10
          - and:
            - mnemonic: shr
            - mnemonic: imul
            - number: 0x66666667
            - number: 0x1f
            - number: 0x2
            - optional:
              - mnemonic: neg
            - description: Compiler optimized returning checkum % 10