APT:Unwrap
Revision as of 05:28, 22 November 2015 by Steveice10 (talk | contribs)
Request
| Index Word | Description |
|---|---|
| 0 | Header code [0x00470104] |
| 1 | Output Size |
| 2 | Input Size |
| 3 | Block Size |
| 4 | Nonce Size (capped to 12) |
| 5 | (Input Size << 4) | 0xA |
| 6 | void*, Input |
| 7 | (Output Size << 4) | 0xC |
| 8 | void*, Output |
Response
| Index Word | Description |
|---|---|
| 0 | Header code |
| 1 | Result code |
Description
This decrypts the input data with AES-CCM using keytype2, when the input noncesize is <12 the low 2-bits are cleared in the noncesize. The 12-byte nonce buffer used by NS is cleared to all-zero, then the nonce from inputbuf+0 with the noncesize is copied to this nonce buffer. NS then uses PS:EncryptSignDecryptVerifyAesCcm with keytype2 and with the above nonce buffer, where the inputptr is inputbuf+noncesize, outputptr is outputbuf+0, and size is inputbuffersize - noncesize - 16.
After decryption, NS copies the data at outbuf+blocksize to outbuf+blocksize+noncesize, with size inputbuffersize-blocksize-16. NS then copies the nonce from inputbuf+0 with the noncesize, to outbuf+blocksize.