firefox-main/security/nss/lib/pkcs7/secmime.c (file symbol)

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/*
* Stuff specific to S/MIME policy and interoperability.
* Depends on PKCS7, but there should be no dependency the other way around.
*/
#include "secmime.h"
#include "secoid.h"
#include "pk11func.h"
#include "ciferfam.h" /* for CIPHER_FAMILY symbols */
#include "secasn1.h"
#include "secitem.h"
#include "cert.h"
#include "keyhi.h"
#include "secerr.h"
static unsigned long smime_policy_bits = 0;
/*
* Based on the given algorithm (including its parameters, in some cases!)
* and the given key (may or may not be inspected, depending on the
* algorithm), find the appropriate policy algorithm specification
* and return it. If no match can be made, -1 is returned.
*/
static long
smime_policy_algorithm(SECAlgorithmID *algid, PK11SymKey *key)
{
SECOidTag algtag;
algtag = SECOID_GetAlgorithmTag(algid);
switch (algtag) {
case SEC_OID_RC2_CBC: {
unsigned int keylen_bits;
keylen_bits = PK11_GetKeyStrength(key, algid);
switch (keylen_bits) {
case 40:
return SMIME_RC2_CBC_40;
case 64:
return SMIME_RC2_CBC_64;
case 128:
return SMIME_RC2_CBC_128;
default:
break;
}
} break;
case SEC_OID_DES_CBC:
return SMIME_DES_CBC_56;
case SEC_OID_DES_EDE3_CBC:
return SMIME_DES_EDE3_168;
default:
break;
}
return -1;
}
static PRBool
smime_cipher_allowed(unsigned long which)
{
unsigned long mask;
which &= ~CIPHER_FAMILYID_MASK;
PORT_Assert(which < 32); /* bits per long (min) */
if (which >= 32)
return PR_FALSE;
mask = 1UL << which;
if ((mask & smime_policy_bits) == 0)
return PR_FALSE;
return PR_TRUE;
}
PRBool
SECMIME_DecryptionAllowed(SECAlgorithmID *algid, PK11SymKey *key)
{
long which;
which = smime_policy_algorithm(algid, key);
if (which < 0)
return PR_FALSE;
return smime_cipher_allowed((unsigned long)which);
}