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PKCS #1: Allow only BT=01 for signature in internal TLS

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Based on PKCS #1, v1.5, 10.1.3, the block type shall be 01 for a
signature. This avoids a potential attack vector for internal TLS/X.509
implementation.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen 2014-05-19 23:26:19 +03:00 committed by Jouni Malinen
parent 9c29d48725
commit e6d83cc7ba
1 changed files with 10 additions and 19 deletions
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15
src/tls/pkcs1.c
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@ -142,26 +142,18 @@ int pkcs1_decrypt_public_key(struct crypto_rsa_key *key,
* BT = 00 or 01 * BT = 00 or 01
* PS = k-3-||D|| times (00 if BT=00) or (FF if BT=01) * PS = k-3-||D|| times (00 if BT=00) or (FF if BT=01)
* k = length of modulus in octets * k = length of modulus in octets
*
* Based on 10.1.3, "The block type shall be 01" for a signature.
*/ */
if (len < 3 + 8 + 16 /* min hash len */ || if (len < 3 + 8 + 16 /* min hash len */ ||
plain[0] != 0x00 || (plain[1] != 0x00 && plain[1] != 0x01)) { plain[0] != 0x00 || plain[1] != 0x01) {
wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature EB " wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature EB "
"structure"); "structure");
return -1; return -1;
} }
pos = plain + 3; pos = plain + 3;
if (plain[1] == 0x00) {
/* BT = 00 */
if (plain[2] != 0x00) {
wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature "
"PS (BT=00)");
return -1;
}
while (pos + 1 < plain + len && *pos == 0x00 && pos[1] == 0x00)
pos++;
} else {
/* BT = 01 */ /* BT = 01 */
if (plain[2] != 0xff) { if (plain[2] != 0xff) {
wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature " wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature "
@ -170,7 +162,6 @@ int pkcs1_decrypt_public_key(struct crypto_rsa_key *key,
} }
while (pos < plain + len && *pos == 0xff) while (pos < plain + len && *pos == 0xff)
pos++; pos++;
}
if (pos - plain - 2 < 8) { if (pos - plain - 2 < 8) {
/* PKCS #1 v1.5, 8.1: At least eight octets long PS */ /* PKCS #1 v1.5, 8.1: At least eight octets long PS */