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--- atracdownload-wiki [2010/06/08 08:37] – created from the FreeMD document about recording megadiscman
+++ atracdownload-wiki [2011/08/10 22:04] (current) – alex
@@ Line 1: / Line 1: @@
-This document is based on [[atracdownload]] from the FreeMD repository
+This document is based on [[atracdownload]] from the FreeMD repository. Also compare http://bertrik.sikken.nl/netmd/download.html
 ====== Downloading an ATRAC track to a NetMD unit ======
@@ Line 25: / Line 25: @@
-==== 1. REQUEST TO START AUTHENTICATION (?) ====
+==== 1. DISABLE TRACK PROTECTION FOR NEXT SESSION ====
   => 00 18 00 08 00 46 f0 03 01 03  2b ff 00 01 00 00 01
   <= 09 18 00 08 00 46 f0 03 01 03  2b 00 00 01 00 00 01
+This instruction tells the MD unit to not set the "protected" bit for following downloaded tracks. It is effective until reset with the same instruction, but having the last byte 00, or the end of the current session.
-==== 2. SPIN UP DISK (?) ====
+==== 2. START AUTHENTICATED SESSION ====
-  => 00 18 00 08 00 46 f0 03 01 03  80 ff 00 00 00 00 00
+  => 00 18 00 08 00 46 f0 03 01 03  80 ff
-  <= 09 18 00 08 00 46 f0 03 01 03  80 00 00 00 00 00 00
+  <= 09 18 00 08 00 46 f0 03 01 03  80 00
 NOTE: You hear head movement (disc spinning up).
@@ Line 41: / Line 42: @@
 ==== 3.  REQUEST FOR LEAF ID ====
-  => 00 18 00 08 00 46 f0 03 01 03  11 ff 00 00 00 00 00
+  => 00 18 00 08 00 46 f0 03 01 03  11 ff
   <= 09 18 00 08 00 46 f0 03 01 03  11 00 01 00 00 21 cf 06 00 00
@@ Line 61: / Line 62: @@
 So the DNK of a device is:
+<code>
 Leaf ID
 Leaf Key, eg
@@ Line 66: / Line 68: @@
 Encrypted node keys, eg:
   E(K0010, KR), E(K0010, K0), E(K0010, K00), E(K0010, K001)
+</code>
 More details on the tree is contained in the EKB.
@@ Line 73: / Line 76: @@
-==== 4. TRANSFER EKB ====
+==== 4. TRANSFER KEY MATERIAL ====
   => 00 18 00 08 00 46 f0 03 01 03 12 ff 00 38 00 00
@@ Line 83: / Line 86: @@
 38 00 00
-Enabling Key Block.  Same for all PCs and all devices as far as I know.
+Part of the Enabling Key Block used by the device.  Same for all PCs and all devices as far as I know.
-"parts of this data is also found in a file in C:\Program Files\Common
+"parts of this data is also found in a file in C:\Program Files\Common Files\Sony Shared\OpenMG\Ekb The 16-byte block starting with 01 ca be .. is identical to the contents of bytes 0x58-0x67 in file 00010001.ekb. The 24-byte block starting with 0f f4 7d .. is identical to the contents of bytes 0x08-0x1f in file 00010001.ekb." (http://bertrik.sikken.nl/netmd/download.html)
-Files\Sony Shared\OpenMG\Ekb The 16-byte block starting with 01 ca be
-.. is identical to the contents of bytes 0x58-0x67 in file
-00010001.ekb. The 24-byte block starting with 0f f4 7d .. is identical
-to the contents of bytes 0x08-0x1f in file 00010001.ekb."
-(http://bertrik.sikken.nl/netmd/download.html)
-The EKB is simply a content-specific root key KR', encrypted by a key
+The EKB is simply a content-specific root key KR', encrypted by a key from the DNK set, ie, one of the keys known by the device (for example K0).  The further up the key is in the hierarchy, the more devices can decrypt the EKB and use the content-specific root key.
-from the DNK set, ie, one of the keys known by the device (for example
-K0).  The further up the key is in the hierarchy, the more devices can
-decrypt the EKB and use the content-specific root key.
-In this case: 01ca... is Enc(K000000010,KR) And 0ff4... is some
+In this case: 01ca... is Enc(K000000010,KR), that is the root key encrypted by a key the device has in its DNK. And 0ff4... is some unknown thing from the EKB 00010001.ekb, probably a digital signature.  See tools/dump-ekb.py for more info on EKBs.
-unknown thing from the EKB 00010001.ekb.  Maybe the encrypted version
-number.  See tools/dump-ekb.py for more info on EKBs.
-Note: According to the patent, an EKB can be used to renew device keys
+Note: According to the patent, an EKB can be used to renew device keys(Key Renewal Block), but I doubt that this is implemented for NetMD devices.
-(Key Renewal Block), but I doubt that this is implemented for NetMD
-devices.
-==== 5. authentication ??? ====
+==== 5. SESSION KEY NEGOTIATION ====
   => 00 18 00 08 00 46 f0 03 01 03 20 ff 00 00 00
      $m(1) ... $m(8)
   <= 09 18 00 08 00 46 f0 03 01 03 20 00 00 00 00
-     !m(1) ... !m(1)
+     !m(1) ... !m(8)
-Send and return differ, and differ in each run.
+$m is a nonce from the host and !m is a nonce from the device. These two 8-byte-values are concatenated to form a 16-byte value. The Retail MAC without padding of that value, using the root key of the EKB transferred as key for the MAC will be the session key.
-==== 6. TRANSFER ENCRYPTED CONTENT KEY ? ====
+For "Retail MAC" aka "CBC-MAC-Y" aka "ISO/IEC 9797-1, algorithm 3" see google. It basically is standard DES CBC-MAC for all but the last blocks, while the last block is encrypted using 3DES-CBC. The initial IV is zero.
+==== 6. TRANSFER CONTENT ID AND ENCRYPTION KEY ====
   => 00 18 00 08 00 46 f0 03 01 03 22 ff 00 00
@@ Line 121: / Line 114: @@
   <= 00 18 00 08 00 46 f0 03 01 03 22 00 00 00
-==== 7. End search and start recording ====
+$m(1) ... $m(32) is DES encrypted using the session key negotiated in the previous step. The corresponding plain text is
+01 01 01 $c(1) ... $c(20) $k(1) ... $k(8)
+where $c(1) ... $c(20) is the Content ID of the track to transfer (a kind of UUID to recognize the copyrighted work) and $k(1) ... $k(8) is the Key Encryption Key.
+==== 7. TRANSFER TRACK DATA ====
   => 00 18 00 08 00 46 f0 03 01 03 28 ff 00 01
@@ Line 129: / Line 128: @@
 ffff is a placeholder for the track number (indicated by 10 01).
-$p$q is the format, 0006 for SP, 9402 for LP2 and a800 for LP4.  $r$s
+$p$q is the format, 0006 for SP, 9402 for LP2 and a800 for LP4.  $r$s for LP2 and LP4 is the number of frames (of 96 bytes for LP4 or 192 bytes for LP2); $t$u$v$w is the number of bytes transferred through the bulk pipe. The number includes the packing overhead.
-is an unknown value proportional to the file size.  $t$u$v$w is the
-size of bytes transfered.
+The meaning or $r$s for SP is not yet known.
 The player returns __twice__ from this command.  First it just echoes it
@@ Line 142: / Line 141: @@
   <= 09 18 00 08 00 46 f0 03 01 03 28 ff 00 01
 10 01 00 !t 00 $p $q 00 00 $r $s $t $u $v $w
+     $m(0) ... $m(32)
 The track number of the recorded track is returned in !t.
-NOTE: We don't know how $p$w is calculated.
+$m(x) is DES CBC encrypted by the session key (IV zero), and after decryption contains the concatenation of
+  - An 8 byte value identifying the track (needed on check-in to verify which copyrighted work will be deleted and adjust the check-out counter)
+  - Four padding bytes (seen as 00 00 00 00 or 01 01 01 01)
+  - The 20-byte Content ID
 NOTE: The data is split into blocks of 3f00 bytes each (except the
 last one), and each one has a header:
-00 00 00 00 00 $u $v $m(1) ... $m(8)
+00 00 00 00 00 $u $v $k(1) ... $k(8) $i(1) ... $i(8)
-where $u$v is the block size (usually 3f00) and $m(x) is unknown
+where $u$v is the block size (usually 3f00), $k(x) is the key for DES CBC encryption of the data in this block, and $i(x) is the IV for the DES CBC encryption. The key itself is DES **decrypted** by the key encryption key, i.e. you have to **encrypt** it to get the plain key.
-(possibly a key).
-This means for the total nr of bytes: len + (len/3f00)*16 + 16
+This means for the total nr of bytes: len + ((len+0x3eff)/3f00)*24
 ==== 8. TOC Edit ====
@@ Line 167: / Line 169: @@
   <= 09 18 08 10 18 02 00 00
-==== 9. Commit ====
+==== 9. COMMIT ====
   => 00 18 00 08 00 46 f0 03 01 03 48 ff 00
@@ Line 174: / Line 176: @@
 01 00 $t
-$t is the track number.  $m(x) is possibly some Integrity Check Value.
+$t is the track number.  $m(x) is a simple authorization value: It's 0000000000000000 DES encrypted by the session key.
-==== 10. ??? ====
+==== 10. FORGET SESSION KEY ====
   => 00 18 00 08 00 46 f0 03 01 03 21 ff 00 00 00
   <= 09 18 00 08 00 46 f0 03 01 03 21 00 00 00 00
-==== 11. ??? ====
+==== 11. END AUTHENTICATED SESSION ====
-  => 00 18 00 08 00 46 f0 03 01 03 81 ff 00 00 00
+  => 00 18 00 08 00 46 f0 03 01 03 81 ff
-  <= 09 18 00 08 00 46 f0 03 01 03 81 00 00 00 00
+  <= 09 18 00 08 00 46 f0 03 01 03 81 00
 ===== Deleting a track (or checking it into the computer) =====
-==== 1. START ====
+==== 1. START AUTHENTICATED SESSION ====
   => 00 18 00 08 00 46 f0 03 01 03 80 ff 00 00 00 00 00
@@ Line 201: / Line 203: @@
   <= 09 18 00 08 00 46 f0 03 01 03 11 00 01 00 00 21 cf 06 00 00
-==== 3. TRANSFER EKB ====
+==== 3. TRANSFER KEY MATERIAL ====
   => 00 18 00 08 00 46 f0 03 01 03 12 ff 00 38 00 00
@@ Line 211: / Line 213: @@
 38 00 00
-==== 4. Get hash id for a track ====
+==== 4. GET TRACK DRM INFO/CONTENT ID/??? ====
   => 00 18 00 08 00 46 f0 03 01 03 23 ff 10 01 00 $t
@@ Line 217: / Line 219: @@
 $t is the track to check in or delete.
-==== 5. Key negotiation? ====
+==== 5. SESSION KEY NEGOTIATION ====
   => 00 18 00 08 00 46 f0 03 01 03 20 ff 00 00 00
@@ Line 224: / Line 226: @@
      !m !n !o !p !q !r !s !t
-==== 6. ====
+==== 6. TWO-STAGE DELETE ====
   => 00 18 00 08 00 46 f0 03 01 03 40 ff 00
 01 00 $t
-  $t is the track to check in or delete.
   <= 00 18 00 08 00 46 f0 03 01 03 40 00 00
 01 00 $t $m(1) ... $m(8)
+$t is the track to check in or delete.
   => 00 18 00 08 00 46 f0 03 01 03 40 ff 01
@@ Line 240: / Line 240: @@
 01 ff fe $m(1) ... $m(8)
-==== 7. ??? ====
+==== 7. FORGET SESSION KEY ====
   => 00 18 00 08 00 46 f0 03 01 03 21 ff 00 00 00
   <= 09 18 00 08 00 46 f0 03 01 03 21 00 00 00 00
-==== 8. ??? ====
+==== 8. END AUTHENTICATED SESSION ====
   => 00 18 00 08 00 46 f0 03 01 03 21 ff 00 00 00