Difference between revisions of "APT:Unwrap"
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(Created page with "=Request= {| class="wikitable" border="1" |- ! Index Word ! Description |- | 0 | Header code [0x00470104] |- | 1 | Output buffer size |- | 2 | Input buffer size |- | 3 | Block ...") |
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=Description= | =Description= | ||
| − | This decrypts the input data with [[PS:EncryptSignDecryptVerifyAesCcm|AES-CCM]] using keytype2. 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. | + | This decrypts the input data with [[PS:EncryptSignDecryptVerifyAesCcm|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. | 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. | ||
Revision as of 23:24, 31 May 2013
Request
| Index Word | Description |
|---|---|
| 0 | Header code [0x00470104] |
| 1 | Output buffer size |
| 2 | Input buffer size |
| 3 | Block size |
| 4 | Nonce size, size 12 is used if this is >12. |
| 5 | (inputbufsize<<4) | 10 |
| 6 | Input encrypted data buffer ptr |
| 7 | (outputbufsize<<4) | 12 |
| 8 | Output cleartext data buffer ptr |
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.