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Add an offset parameter to mifare_cryto_preprocess_data()

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Some cryptographic operations are performed on the whole data frame and not
only the payload with Mifare DESFire EV1.  The solution for now is not perfect,
(one new macro wrapping another big macro) but makes the code a bit easier to
read, and with the MIFARE_DESFIRE macro rewriting as a function (at some point
in the future), the whole should be bearable :-)
This commit is contained in:
Romain Tartiere 2010-11-20 14:10:27 +00:00
parent 16ae154b42
commit a643e9149d
3 changed files with 42 additions and 44 deletions
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18
libfreefare/mifare_desfire_authenticate.c
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@ -131,11 +131,15 @@ assert_crypto_buffer_size (MifareTag tag, size_t nbytes)
}
void *
mifare_cryto_preprocess_data (MifareTag tag, void *data, size_t *nbytes, int communication_settings)
mifare_cryto_preprocess_data (MifareTag tag, void *data, size_t *nbytes, off_t offset, int communication_settings)
{
void *res;
uint8_t mac[4];
size_t edl, mdl;
MifareDESFireKey key = MIFARE_DESFIRE (tag)->session_key;
if (!key)
return data;
switch (communication_settings) {
case 0:
@ -143,7 +147,7 @@ mifare_cryto_preprocess_data (MifareTag tag, void *data, size_t *nbytes, int com
res = data;
break;
case 1:
edl = padded_data_length (*nbytes, key_block_size (MIFARE_DESFIRE (tag)->session_key));
edl = padded_data_length (*nbytes - offset, key_block_size (MIFARE_DESFIRE (tag)->session_key)) + offset;
if (!(res = assert_crypto_buffer_size (tag, edl)))
abort();
@ -152,11 +156,11 @@ mifare_cryto_preprocess_data (MifareTag tag, void *data, size_t *nbytes, int com
// ... and 0 padding
bzero ((uint8_t *)res + *nbytes, edl - *nbytes);
mifare_cbc_des (MIFARE_DESFIRE (tag)->session_key, MIFARE_DESFIRE (tag)->ivect, res, edl, MD_SEND, 1);
mifare_cbc_des (MIFARE_DESFIRE (tag)->session_key, MIFARE_DESFIRE (tag)->ivect, (uint8_t *) res + offset, edl - offset, MD_SEND, 1);
memcpy (mac, (uint8_t *)res + edl - 8, 4);
mdl = maced_data_length (MIFARE_DESFIRE (tag)->session_key, *nbytes);
mdl = maced_data_length (MIFARE_DESFIRE (tag)->session_key, *nbytes - offset) + offset;
if (!(res = assert_crypto_buffer_size (tag, mdl)))
abort();
@ -167,20 +171,20 @@ mifare_cryto_preprocess_data (MifareTag tag, void *data, size_t *nbytes, int com
break;
case 3:
edl = enciphered_data_length (MIFARE_DESFIRE (tag)->session_key, *nbytes);
edl = enciphered_data_length (MIFARE_DESFIRE (tag)->session_key, *nbytes - offset) + offset;
if (!(res = assert_crypto_buffer_size (tag, edl)))
abort();
// Fill in the crypto buffer with data ...
memcpy (res, data, *nbytes);
// ... CRC ...
iso14443a_crc_append (res, *nbytes);
iso14443a_crc_append ((uint8_t *)res + offset, *nbytes - offset);
// ... and 0 padding
bzero ((uint8_t *)(res) + *nbytes + 2, edl - *nbytes - 2);
*nbytes = edl;
mifare_cbc_des (MIFARE_DESFIRE (tag)->session_key, MIFARE_DESFIRE (tag)->ivect, res, *nbytes, MD_SEND, 0);
mifare_cbc_des (MIFARE_DESFIRE (tag)->session_key, MIFARE_DESFIRE (tag)->ivect, (uint8_t *) res + offset, *nbytes - offset, MD_SEND, 0);
break;
default: