APT:Unwrap: Difference between revisions

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|-
|-
| 1
| 1
| Output buffer size
| Output Size
|-
|-
| 2
| 2
| Input buffer size
| Input Size
|-
|-
| 3
| 3
| Block size
| Block Size
|-
|-
| 4
| 4
| Nonce size, size 12 is used if this is >12.
| Nonce Size (capped to 12)
|-
|-
| 5
| 5
| (inputbufsize<<4) <nowiki>|</nowiki> 10
| (Input Size << 4) <nowiki>|</nowiki> 0xA
|-
|-
| 6
| 6
| Input encrypted data buffer ptr
| void*, Input
|-
|-
| 7
| 7
| (outputbufsize<<4) <nowiki>|</nowiki> 12
| (Output Size << 4) <nowiki>|</nowiki> 0xC
|-
|-
| 8
| 8
| Output cleartext data buffer ptr
| void*, Output
|}
|}



Revision as of 05:28, 22 November 2015

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.