| 4 | < *Koptekst 3L *OpsomtekenO ³ • Swiss ÿÿÿÿ h 3 r h 3 r Ð Ð e f d e f L d ý ‚. ÆA ID Section Name «Word File» 10000106 «Text Section» «Sheet File» 1000011D 10000121 «Sheet Graph List Section»[Encryption Method]Encryption MethodThe plaintext is separated into blocks of 20 bytes. The last block is padded with bytes containing 30. Each block is encypted by adding a 20 byte long key. This key is somehow based on the plaintext password (probably through a similar, though different, hash function as that which is used to encrypt the password), and it is the same for each block. The resulting encryption seems to be fairly weak. For a word file, for example, you can gather a lot of information from the other (unencrypted) sections; for a longer text, this is probably enough to break the encryption key, without ever needing the plaintext password! This could even be automated somewhat: if there is a ParagraphElement List, you know the length of each paragraph; you also know that (almost) all paragraphs end with a 06 byte. ð " Courier New ð "Times New Roman " Courier New ‰ t V $ ' * a à ð
@ "Arial ð "Times New Roman " Courier New " Courier New ð "Times New Roman ð "Times New Roman " Courier New " " Courier New " Courier New " Courier New " Courier New È " Courier New ð "Times New Roman ð "Times New Roman  ð "Word.app C " y ‰ K |
4 | < *Koptekst 3L *OpsomtekenO ³ • Swiss ÿÿÿÿ h 3 r h 3 r Ð Ð e f d e f L d ý ‚. ÆA ID Section Name «Word File» 10000106 «Text Section» «Sheet File» 1000011D 10000121 «Sheet Graph List Section»[Encryption Method]Encryption MethodThe plaintext is separated into blocks of 20 bytes. The last block is padded with bytes containing 30. Each block is encypted by adding a 20 byte long key. This key is somehow based on the plaintext password (probably through a similar, though different, hash function as that which is used to encrypt the password), and it is the same for each block. The resulting encryption seems to be fairly weak. For a word file, for example, you can gather a lot of information from the other (unencrypted) sections; for a longer text, this is probably enough to break the encryption key, without ever needing the plaintext password! This could even be automated somewhat: if there is a Paragraph Element List, you know the length of each paragraph; you also know that (almost) all paragraphs end with a 06 byte. ð " Courier New ð "Times New Roman " Courier New ‰ t V $ ' * a à ð
@ "Arial ð "Times New Roman " Courier New " Courier New ð "Times New Roman ð "Times New Roman " Courier New " " Courier New " Courier New " Courier New " Courier New È " Courier New ð "Times New Roman ð "Times New Roman  ð "Word.app C " y ‰ K |
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