iniitl;a commit

tools/Filesystem/SEGA_Decryption_Guide.txt

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+╔═════════════════════╗
+ SEGA Decryption Guide
+╚═════════════════════╝
+
+╭─────────╮
+ app files
+╰─────────╯
+
+1. create a new file titled <PCB CODE>.bin
+
+2. fill in the first 16 bytes of <PCB CODE>.bin with
+the AES key. (e.g. 9D 0B BA 20 D1 E8 4F 24 59 39 9F 53 83 BE EE 72)
+
+3. the next 16 bytes will be the NTFS header (EB 52 90 4E 54 46 53 20 20 20 20 00 10 01 00 00)
+the NTFS header is always the same
+
+4. save this file, then decrypt the app files with the following command:
+fsdecrypt <PCB CODE>.bin 0x200000 <path/to/app> <out.vhd>
+
+5. once it finishes decrypting, run the calculate_iv.py script
+save the output of key 1. script is found here: https://discord.com/channels/162861213309599744/243895668790394882/995170669329391706
+
+6. open <PCB CODE>.bin inside the hex editor once more, replace the NTFS header with
+the key 1
+
+7. run "fsdecrypt <PCB CODE>.bin 0x200000 <path/to/app> <out.vhd>" once more
+
+8. your app is now decrypted, you can extract the internal_0 with poweriso or any other tool
+
+╭─────────╮
+ opt files
+╰─────────╯
+
+1. decrypt the opt file using fstools with the following command:
+fstool dec OPT.bin in.opt out.vhd
+
+2. run the calculate_iv.py script and save key 3
+script is found here: https://discord.com/channels/162861213309599744/243895668790394882/995170669329391706
+
+3. replace the IV key of the OPT.bin with key 3, the IV key of OPT.bin are the second 16 bytes
+
+4. decrypt the opt file once more with the new key

tools/Filesystem/calculate_iv/calculate_iv.py

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+# Get the IV key from OPT.bin (this is the second 16 bytes of the file)
+# decrypt the .opt using OPT.bin and get the first 16 bytes of the vhd. this is key1
+# key1 xor EB769045584641542020200000000000 (exfat file header) this will give you key2
+# key2 xor OPT IV key -> key3
+# replace OPT.bin's IV with key3 and decrypt
+import os
+import glob
+
+#function for taking bytes and xor'ing them
+def byte_xor(ba1, ba2):
+    return bytes([_a ^ _b for _a, _b in zip(ba1, ba2)])
+
+print("You must decrypt the opt first using fstools and the OPT.bin\nPlace everything in the same directory\nONLY HAVE ONE VHD IN THE DIRECTORY AT A TIME")
+cwd = os.getcwd()
+
+#necessary because i couldn't figure out how else to do this, it's the exfat header duh
+with open(str(cwd) + "/exfat.bin", "rb") as f:
+	exfat_HEADER = f.read(-1)
+	print("exFAT Header = " + str(exfat_HEADER.hex()))
+
+#reads all bytees from OPT.bin then saves bytes (17, 32) and converts it to hexadecimal
+with open(str(cwd) + "/OPT.bin", "rb") as f:
+	opt_IV = f.read(-1)
+	opt_IV = opt_IV[16:]
+	print("OPT IV = " + str(opt_IV.hex()))
+
+#puts all files with .vhd extension in a list, then pulls the first one in the list, will read first 16 bytes and convert to hexadecimal
+placeholder = glob.glob("*.vhd")
+vhd = str(placeholder[0])
+with open(str(cwd) + "/" + vhd, "rb") as f:
+	key1 = f.read(16)
+	print("key1 =" + str(key1.hex()))
+
+#calculates key 2 and key 3 then converts to hex
+key2 = byte_xor(key1, exfat_HEADER)
+print("key2 = " + str(key2.hex()))
+key3 = byte_xor(key2, opt_IV)
+print("key3 = " + str(key3.hex()))
+

tools/Filesystem/calculate_iv/calculate_iv.txt

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+i saw some of you guys were struggling with calculating the key3 so i went ahead and wrote a script for you all that does it for you. no external libraries are used, everything is just python3
+exfat.bin is necessary, it stores the exfat header within it

tools/Filesystem/sega_iv_chinese.txt

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+1.Create SDDT.bin with 16 bytes of 0 written in the iv key
+2.Decrypt only the first 16 bytes once with fsdecrypt or fstool
+3.The first 16 bytes of the decrypted file is the iv key
+1.创建SDDT.bin，在iv键中写入16个字节的0
+2.用fsdecrypt或fstool只对前16个字节进行一次解密
+3.解密后的文件的前16个字节是iv密钥