Minidriver function CardRSADecrypt returns incorrect length when unpadding SC_ALGORITHM_RSA_RAW/CARD_PADDING_PKCS1

[jozsefd]

Problem Description

Minidriver function CardRSADecrypt returns incorrect length when unpadding SC_ALGORITHM_RSA_RAW data as CARD_PADDING_PKCS1 using the function sc_pkcs1_strip_02_padding_constant_time(). The function sc_pkcs1_strip_02_padding_constant_time() sets the last output parameter to modulus_length / 8 - SC_PKCS1_PADDING_MIN_SIZE, not the actual length of the unpadded data, on the other hand, the function returns the correct length.

Proposed Resolution

// pInfo->cbData = (DWORD) temp;
pInfo->cbData = (DWORD) r;

Steps to reproduce

This isssue can be reproduced only after #3084 and #3085 has been fixed. It can be reproduced with a windows application calling API CryptDecrypt() with a card using raw RSA (like nqApplet).
The following commit contains all 3 fixes: 723209f

Logs

The expected length of the decrypted data after unpadding was 128, but got 373:
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] sec.c:50:sc_decipher: returning with: 384
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] card.c:523:sc_unlock: called
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] pkcs15-sec.c:169:use_key: returning with: 384
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] sc_pkcs15_decipher: DECRYPT-INFO dwVersion=2
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] sc_pkcs15_decipher: stripping PKCS1 padding
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] padding.c:159:sc_pkcs1_strip_02_padding_constant_time: called
P:20068; T:21236 2024-03-22 08:30:24.185 [cardmod] decrypted data(373):

[jozsefd]

#3077 will fix this problem.

[jozsefd]

I have tested #3077 with various cards, it fixes this issue.