Office 97, 2000, XP and 2003 use RC4 with 40 bits. They can be cracked instantly with the help of precomputation tables. Because it's only like a Vigenere Cipher. Hacking software is now readily available to find a 16-byte key and decrypt the password-protected document. In Excel and Word 95 and prior editions a weak protection algorithm is used that converts a password to a 16-bit verifier and a 16-byte XOR obfuscation array (page 60/119) key. History of Office Encryption Weak encryptions In Excel passwords restrict modification of the workbook, a worksheet within it, or individual elements in the worksheet.In Word and PowerPoint the password restricts modification of the entire document.Passwords that do not encrypt, but restrict modification.If the password can be determined through social engineering, the underlying cipher is not important. Since Office 2007 they are hard to break, if a sufficient complex password was chosen. This is possible in all Microsoft Office applications. A password to encrypt a document restricts opening and viewing it.There are two groups of passwords that can be set to a document: Microsoft Office password protection is a security feature to protect Microsoft Office documents (Word, Excel, PowerPoint) with a user-provided password.
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