Differences

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--- devicesal [2009/05/05 07:35] – created dummy megadiscman
+++ devicesal [2009/05/27 12:31] – example for ssatrans marcus
@@ Line 1: / Line 1: @@
-dummy
+Missing Info:
+<code>
+Dict 0xfc - contains an unknown 8 byte key, used in dev_0xd8, dev_0xd9.
+</code>
+Native modules:
+<code>
+// CBC Encrypt/Decrypt.  The OUT buffer must be pre-allocated.
+// Block size of the cipher is 64 bit, key length is 160 bit.
+blob_t
+native::ocmmod (blob_t in, blob_t out, blob_t key, int len, int decrypt)
+{
+  if (decrypt)
+    ocmmod_cbc_decrypt (in, out, key, len);
+  else
+    ocmmod_cbc_encrypt (in, out, key, blob_len (in));
+  return out;
+}
+</code>
+<code>
+int
+dev_0x01 (blob_t someblob, bool_t somebool)
+{
+  int res;
+  if (somebool == 1)
+    {
+      res = dev_0x00 (someblob);
+      if (res != 0)
+        return res;
+    }
+  int some_nr = (unsigned) SubBlob (someblob, 0, 4);
+  int some_nr2 = (unsigned) dev_0xd1 (some_nr);
+  res = "localekb" (some_nr2);
+  // FIXME: Don't know the stack layout after this.
+  if (res != 0)
+    return;  // but what?
+  blob_t someblob2;  // probably from localekb
+  int some_nr3 = (signed) SubBlob (someblob2, 0, 4) + 1;
+  vector<blob_t> vec;
+  do
+    {
+      vec.append (SubBlob (some_nr3 * 16, 24));
+    }
+  while (some_nr3-- >= 0);
+  int some_nr3 = (signed) SubBlob (someblob2, 0, 4);
+  res = dev_0xc1 (some_nr3);
+  if (res != 0)
+     return res;
+  int some_nr4 = (signed) SubBlob (someblob2, 16, 4);
+  if (some_nr3 == some_nr4)
+    return 0;
+  else
+    return 8;
+  // is vec returned as well?  it's still on the stack.
+}
+int
+dev_0xb7 (any_t thing)
+{
+  if (get_type (thing) != TYPE_BLOB)
+    return 0;
+  if (thing[2] == 0x31)
+    return 2;
+  else
+    {
+      if (! strncmp (thing, "\x31\x31", 2))
+        return 1;
+      else
+        return 0;
+    }
+}
+block_t
+dev_0xd1 (int nr)
+{
+  if (nr > 1)
+    {
+x80 ("Invalid version...");
+      return 0;
+    }
+  else
+    {
+      return 00 81 00 00 00 00 00 00;
+    }
+}
+// Some decrypt function.
+// KEYBLOB seems to be 16 byte in practice.
+any_t
+dev_0xd8 (blob_t ciphertext, blob_t keyblob)
+{
+  blob_t key = keyblob XOR concat (dict[0xfc], dict[0xfc]);
+  // Side-effect.
+  dict[0xdb] = key;
+  blob_t hashed_key = SHA1 (key[0..14]);
+  blob_t des_iv = hashed_key[0..7];
+  blob_t des_key = hashed_key[8..15]
+  blob_t data = DES_CBC_Decrypt (ciphertext, des_iv, des_key, 0xd8_DESDecrypt);
+  // Decrypt with ocmmod cipher.
+  int len = blob_length (data);
+  // Round up to multiple of 8.
+  len = (len + 7) / 8 * 8;
+  blob_t plaintext = repeat_nul (len);
+  plaintext = native::ocmmod (data, plaintext, hashed_key, len, 1);
+  // Return deserialized object.
+  return decode_asn1 (plaintext);
+}
+// Some encrypt function.
+// KEYBLOB seems to be 16 byte in practice.
+blob_t
+dev_0xd9 (any_t plainobj, blob_t keyblob)
+{
+  blob_t key = keyblob XOR concat (dict[0xfc], dict[0xfc]);
+  // Side-effect.
+  dict[0xdb] = key;
+  // Serialization.
+  plaintext = encode_asn1 (plaintext);
+  // Encrypt with ocmmod cipher.
+  int len = blob_length (data);
+  // Round up to multiple of 8.
+  len = (len + 7) / 8 * 8;
+  blob_t data = repeat_nul (len);
+  blob_t hashed_key = SHA1 (key[0..14]);
+  data = native::ocmmod (plaintext, data, hashed_key, len, 0);
+  // Encrypt DES.
+  blob_t des_iv = hashed_key[0..7];
+  blob_t des_key = hashed_key[8..15]
+  blob_t ciphertext = DES_CBC_Decrypt (data, des_iv, des_key, 0xd7_DESEncrypt);
+  return ciphertext;
+}
+</code>
+NOT part of device.sal, but for lack of a better place, here an example of SsaTrans on updater.ocm:
+<code>
+$ SsaTrans updater.ocm
+BCSeedRand63 (1, "j5\162\GS\140<,\f");
+BCSetCryptTable ("L\225\164\152\DC1\RSD?\216f\198!\196\154\154\201\195b \192l^V\176r\245\151*\245[[\DC1\NULV#"...);
+v_39 = BCNewBlob (8);
+v_41 = BCDES_SetKey ("\188k\180(\150\EOT,\138");
+arg_0 = Unknown
+v_43 = BCDES_CBC BCDDecrypt (arg_0, v_39, v_41, "\216");
+v_44 = BCBlobLength (v_43);
+v_46 = BCBlobLength ("<!--omg certificated-->");
+v_49 = BCSubBlob (v_43, v_44 - v_46, -1);
+v_51 = BCCompareBlob (v_49, "<!--omg certificated-->");
+if (v_51 == 0) [1 -> 1]
+  {
+    return [v_43, 1];
+  }
+else [1 -> 1]
+  {
+    return [0];
+  }
+v_56 = BCIfElse (v_43);
+v_57 = BCSerialize (v_56);
+return v_57;
+</code>