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Constant time RSA PKCS#1 v1.5 depadding #2948

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merged 8 commits into from
Feb 5, 2024
Merged

Constant time RSA PKCS#1 v1.5 depadding #2948

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b9e1d34
Reimplement removing of PKCS#1 v1.5 padding to be time constant
xhanulik Nov 13, 2023
708ce24
Add unit tests for PKCS#1 v1.5 de-padding
xhanulik Nov 13, 2023
1a6a18c
pkcs15-sec: Remove logging after PKCS#1 v1.5 depadding
xhanulik Nov 16, 2023
a8ac593
framework-pkcs15.c: Handle PKCS#1 v1.5 depadding constant-time
xhanulik Nov 16, 2023
32cdab4
mechanism: Handle PKCS#1 v1.5 depadding constant-time
xhanulik Jan 8, 2024
1fe1a78
minidriver: Make CardRSADecrypt constant-time
xhanulik Nov 22, 2023
306dc92
pkcs11-object: Remove return value logging
xhanulik Nov 24, 2023
aa6bf2b
misc: Compare return value constant-time
xhanulik Nov 24, 2023
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mechanism: Handle PKCS#1 v1.5 depadding constant-time
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@xhanulik
xhanulik committed Jan 31, 2024
commit 32cdab44f6b1e6343f029879a8ab32de4f32743f
19 changes: 14 additions & 5 deletions src/pkcs11/mechanism.c
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,9 @@
#include <stdlib.h>
#include <string.h>

#include "sc-pkcs11.h"
#include "common/compat_overflow.h"
#include "common/constant-time.h"
#include "sc-pkcs11.h"

/* Also used for verification data */
struct hash_signature_info {
Expand Down Expand Up @@ -1093,7 +1094,9 @@ sc_pkcs11_decr(struct sc_pkcs11_session *session,
rv = op->type->decrypt(op, pEncryptedData, ulEncryptedDataLen,
pData, pulDataLen);

if (rv != CKR_BUFFER_TOO_SMALL && pData != NULL)
/* terminate session for any return value except CKR_BUFFER_TOO_SMALL,
* perform check in time side-channel free way to prevent Marvin attack */
if (!constant_time_eq_s(rv, CKR_BUFFER_TOO_SMALL) && pData != NULL)
session_stop_operation(session, SC_PKCS11_OPERATION_DECRYPT);

return rv;
Expand All @@ -1114,10 +1117,12 @@ sc_pkcs11_decr_update(struct sc_pkcs11_session *session,
rv = op->type->decrypt_update(op, pEncryptedData, ulEncryptedDataLen,
pData, pulDataLen);

/* terminate session for any error except CKR_BUFFER_TOO_SMALL */
if (rv != CKR_OK && rv != CKR_BUFFER_TOO_SMALL)
/* terminate session for any return value except CKR_BUFFER_TOO_SMALL,
* perform check in time side-channel free way to prevent Marvin attack */
if (~constant_time_eq_s(rv, CKR_OK) & ~constant_time_eq_s(rv, CKR_BUFFER_TOO_SMALL))
session_stop_operation(session, SC_PKCS11_OPERATION_DECRYPT);
LOG_FUNC_RETURN(context, (int)rv);
/* do not log error code to prevent side channel attack */
return rv;
}

CK_RV
Expand Down Expand Up @@ -1536,6 +1541,10 @@ sc_pkcs11_decrypt(sc_pkcs11_operation_t *operation,
if (pulDataLen)
*pulDataLen = ulDataLen;

/* Skip DecryptFinalize for PKCS#1 v1.5 padding to prevent time side-channel leakage */
if (((CK_MECHANISM_PTR)&operation->mechanism)->mechanism == CKM_RSA_PKCS)
return rv;

if (rv != CKR_OK)
return rv;

Expand Down