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ic:labs:05 [2023/10/01 23:26] razvan.smadu [Exercițiul 3 (5p)] |
ic:labs:05 [2023/10/09 23:22] (current) razvan.smadu |
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| În acest laborator vom face niște exerciții ce folosesc algoritmul DES și variații ale acestuia discutate la [[https://drive.google.com/file/d/1Fjybv6k5QudRB1bkAi5shVUGlUyTO_0U/view|curs]]. | În acest laborator vom face niște exerciții ce folosesc algoritmul DES și variații ale acestuia discutate la [[https://drive.google.com/file/d/1Fjybv6k5QudRB1bkAi5shVUGlUyTO_0U/view|curs]]. | ||
| Prezentarea PowerPoint pentru acest laborator poate fi găsită [[https://drive.google.com/file/d/1FU422fCHM24fRnMuzFd0OjhQqT6AQZ3X/view?usp=sharing|aici]]. | Prezentarea PowerPoint pentru acest laborator poate fi găsită [[https://drive.google.com/file/d/1FU422fCHM24fRnMuzFd0OjhQqT6AQZ3X/view?usp=sharing|aici]]. | ||
| - | Puteți lucra acest laborator folosind și platforma Google Colab, accesând [[https://colab.research.google.com/drive/1Vi5V7mHYIau6vbGFiQITd2FRzYRT3o1j?usp=sharing|acest]] link. | + | Puteți lucra acest laborator folosind platforma Google Colab, accesând [[https://colab.research.google.com/github/ACS-IC-labs/IC-labs/blob/main/labs/lab05/lab5.ipynb|acest]] link. |
| + | <hidden> | ||
| <spoiler Click pentru a vedea utils.py> | <spoiler Click pentru a vedea utils.py> | ||
| <file python utils.py> | <file python utils.py> | ||
| Line 501: | Line 502: | ||
| def des2_enc(k1: bytes, k2: bytes, m: bytes) -> bytes: | def des2_enc(k1: bytes, k2: bytes, m: bytes) -> bytes: | ||
| - | # TODO 3.B: implement des2_enc | + | # TODO B.1: implement des2_enc |
| raise NotImplementedError("Not implemented") | raise NotImplementedError("Not implemented") | ||
| def des2_dec(k1: bytes, k2: bytes, c: bytes) -> bytes: | def des2_dec(k1: bytes, k2: bytes, c: bytes) -> bytes: | ||
| - | # TODO 3.B: implement des2_dec | + | # TODO B.2: implement des2_dec |
| raise NotImplementedError("Not implemented") | raise NotImplementedError("Not implemented") | ||
| Line 517: | Line 518: | ||
| c2 = "54826ea0937a2c34d47f4595f3844445520c0995331e5d492f55abcf9d8dfadf" | c2 = "54826ea0937a2c34d47f4595f3844445520c0995331e5d492f55abcf9d8dfadf" | ||
| - | # TODO: Convert k1, k2, c1, and c2 to bytes. It may make the exercise | + | # TODO C: Decrypt c1 and c2 using k1 and k2, and make sure that |
| + | # des2_dec(k1, k2, c1 || c2) == m1 || m2 | ||
| + | |||
| + | # TODO C.1: Convert k1, k2, c1, and c2 to bytes. It may make the exercise | ||
| # easier to implement. Use string_to_bytes() for plain texts (i.e., string | # easier to implement. Use string_to_bytes() for plain texts (i.e., string | ||
| # in human-readable format), and bytes.fromhex() for hex strings. | # in human-readable format), and bytes.fromhex() for hex strings. | ||
| Line 525: | Line 529: | ||
| c2 = ... | c2 = ... | ||
| - | # TODO 3.C: Decrypt c1 and c2 using k1 and k2, and make sure that | ||
| - | # des2_dec(k1, k2, c1 || c2) == m1 || m2 | ||
| - | # | ||
| # NOTE: The code to decrypt c1 is already provided below. You **need** | # NOTE: The code to decrypt c1 is already provided below. You **need** | ||
| # to decrypt c2 as well. | # to decrypt c2 as well. | ||
| - | # | ||
| m1 = bytes_to_string(des2_dec(k1, k2, c1)) | m1 = bytes_to_string(des2_dec(k1, k2, c1)) | ||
| assert m1 == m1_given, f'Expected "{m1_given}", but got "{m1}"' | assert m1 == m1_given, f'Expected "{m1_given}", but got "{m1}"' | ||
| Line 538: | Line 538: | ||
| print("plaintext in hexa:", str_2_hex(m1)) | print("plaintext in hexa:", str_2_hex(m1)) | ||
| + | # TODO C.2: Decrypt m2 similar to m1. Keep in mind that des_dec() | ||
| + | # returns bytes | ||
| m2 = ... | m2 = ... | ||
| Line 544: | Line 546: | ||
| print("plaintext in hexa:", str_2_hex(m2)) | print("plaintext in hexa:", str_2_hex(m2)) | ||
| + | # TODO C.3: Just to make sure you implemented the task correctly: | ||
| + | # des2_dec(k1, k2, c1 || c2) == m1 || m2 | ||
| m12 = ... | m12 = ... | ||
| assert m12 == m1 + m2, f'Expected "{m12}" to equal "{m1 + m2}"' | assert m12 == m1 + m2, f'Expected "{m12}" to equal "{m1 + m2}"' | ||
| Line 549: | Line 553: | ||
| def mitm() -> None: | def mitm() -> None: | ||
| - | # TODO 3.D: run meet-in-the-middle attack for the following | + | # TODO D: run meet-in-the-middle attack for the following plaintext/ciphertext |
| - | # plaintext/ciphertext | + | |
| m1 = "Pocainta" | m1 = "Pocainta" | ||
| c1 = "9f98dbd6fe5f785d" | c1 = "9f98dbd6fe5f785d" | ||
| Line 556: | Line 559: | ||
| c2 = "6e266642ef3069c2" | c2 = "6e266642ef3069c2" | ||
| - | # TODO: Convert m1, m2, c1, and c2 to bytes. It may make the exercise | + | # TODO D.1: Convert m1, m2, c1, and c2 to bytes. It may make the exercise |
| # easier to implement. Use string_to_bytes() for plain texts (i.e., string | # easier to implement. Use string_to_bytes() for plain texts (i.e., string | ||
| # in human-readable format), and bytes.fromhex() for hex strings. | # in human-readable format), and bytes.fromhex() for hex strings. | ||
| Line 564: | Line 567: | ||
| c2 = ... | c2 = ... | ||
| - | # NOTE: you only need to search for the first 2 bytes of the each key (i.e., | + | # NOTE: You only need to search for the first 2 bytes of the each key (i.e., |
| - | # to find out what are the values for each `?`) | + | # to find out what are the values for each `?`). |
| k1 = "??oIkvH5" | k1 = "??oIkvH5" | ||
| k2 = "??GK4EoU" | k2 = "??GK4EoU" | ||
| + | |||
| + | # TODO D.2: Generate the table containing (k2, DES(k2, m1)), for every | ||
| + | # possible k2. Use a List[Tuple[bytes, bytes]] for the table (see task | ||
| + | # description above). | ||
| + | |||
| + | # TODO D.3: Sort the table based on the ciphertexts. Extract the ciphertexts | ||
| + | # in a list (see task description above). | ||
| + | |||
| + | # TODO D.4: Perform binary search for all possible k1, such that . | ||
| + | # Save the set of candidate keys (k1, k2) in a list. | ||
| + | |||
| + | # TODO D.5: From the set of candidate keys, print the ones matching | ||
| + | # the second constraint: 2DES(k1, k2, m2) == c2 | ||
| Line 576: | Line 592: | ||
| if __name__ == "__main__": | if __name__ == "__main__": | ||
| - | main() | + | main()</file> |
| - | </file> | + | |
| </spoiler> | </spoiler> | ||
| + | </hidden> | ||
