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pkcs5: Parse PRF algorithms if given in PBKDF2-params as defined in RFC 8018

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We can't use ASN1_DEF, which would technically be more correct, as the
ASN.1 parser currently can't handle that.  For algorithm identifiers we
often use ASN1_EOC as type (with ASN1_RAW), however, that doesn't work with
ASN1_DEF because the element is assumed missing if the type doesn't match.
On the other hand, we can't set the type to ASN1_SEQUENCE because then the
parser skips the following rule if the element is missing (it does so for
all constructed types, but I guess is mainly intended for context tags),
which in this case overruns the parser rules array.
This commit is contained in:
Tobias Brunner
2018-03-07 15:23:03 +01:00
parent e5c5792ff8
commit 5808467ed1
1 changed files with 19 additions and 5 deletions
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src/libstrongswan/crypto/pkcs5.c
+19 -5
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@@ -422,7 +422,9 @@ static bool parse_pbes1_params(private_pkcs5_t *this, chunk_t blob, int level0)
/**
* ASN.1 definition of a PBKDF2-params structure
* The salt is actually a CHOICE and could be an AlgorithmIdentifier from
* PBKDF2-SaltSources (but as per RFC 2898 that's for future versions).
* PBKDF2-SaltSources (but as per RFC 8018 that's for future versions).
* The PRF algorithm is actually defined as DEFAULT and not OPTIONAL, but the
* parser can't handle ASN1_DEF with SEQUENCEs.
*/
static const asn1Object_t pbkdf2ParamsObjects[] = {
{ 0, "PBKDF2-params", ASN1_SEQUENCE, ASN1_NONE }, /* 0 */
@@ -430,7 +432,8 @@ static const asn1Object_t pbkdf2ParamsObjects[] = {
{ 1, "iterationCount",ASN1_INTEGER, ASN1_BODY }, /* 2 */
{ 1, "keyLength", ASN1_INTEGER, ASN1_OPT|ASN1_BODY }, /* 3 */
{ 1, "end opt", ASN1_EOC, ASN1_END }, /* 4 */
{ 1, "prf", ASN1_EOC, ASN1_DEF|ASN1_RAW }, /* 5 */
{ 1, "prf", ASN1_SEQUENCE, ASN1_OPT|ASN1_RAW }, /* 5 */
{ 1, "end opt", ASN1_EOC, ASN1_END }, /* 6 */
{ 0, "exit", ASN1_EOC, ASN1_EXIT }
};
#define PBKDF2_SALT 1
@@ -446,13 +449,15 @@ static bool parse_pbkdf2_params(private_pkcs5_t *this, chunk_t blob, int level0)
asn1_parser_t *parser;
chunk_t object;
int objectID;
bool success;
bool success = FALSE;
parser = asn1_parser_create(pbkdf2ParamsObjects, blob);
parser->set_top_level(parser, level0);
/* keylen is optional */
this->keylen = 0;
/* defaults to id-hmacWithSHA1 */
this->data.pbes2.prf_alg = PRF_HMAC_SHA1;
while (parser->iterate(parser, &objectID, &object))
{
@@ -474,13 +479,22 @@ static bool parse_pbkdf2_params(private_pkcs5_t *this, chunk_t blob, int level0)
break;
}
case PBKDF2_PRF:
{ /* defaults to id-hmacWithSHA1, no other is currently defined */
this->data.pbes2.prf_alg = PRF_HMAC_SHA1;
{
int oid;
oid = asn1_parse_algorithmIdentifier(object,
parser->get_level(parser) + 1, NULL);
this->data.pbes2.prf_alg = pseudo_random_function_from_oid(oid);
if (this->data.pbes2.prf_alg == PRF_UNDEFINED)
{ /* unsupported PRF algorithm */
goto end;
}
break;
}
}
}
success = parser->success(parser);
end:
parser->destroy(parser);
return success;
}