On 2010-07-26 06:07 PDT, Hanno Böck wrote:
> Hi,
>
> Just recently, the templates for decoding the RSA-PSS ASN1 parameters got
> added to cvs head (in cryptohi/seckey.c).
>
> Currently I'm working on implementing the creation of PSS signatures, so I
> need them also to encode. My naive thought was that SEC_ASN1EncodeItem is
> used
> pretty much the same as QuickDERDecodeItem, just the other way round.
>
> For testing, I tested with a stripped-down version of the template containing
> only the first entry. Though what I get is:
> Assertion failure: theTemplate->sub != NULL, at secasn1u.c:93
>
>
> From the error, I assume it has something to do with the subtemplate. If that
> helps, by some try and error I found out that when removing
> SEC_ASN1_EXPLICIT,
> no assertion appears (thouhg it'll obviously produce a wrong DER struct).
> Is there something special I need to care about when doing encoding vs.
> decoding ASN1?
>
>
> The code looks like this:
>
>
> SEC_ASN1_MKSUB(SECOID_AlgorithmIDTemplate)
>
> const SEC_ASN1Template MY_RSAPSSParamsTemplate[] =
> {
> { SEC_ASN1_SEQUENCE, 0, NULL, sizeof(SECKEYRSAPSSParams) },
> { SEC_ASN1_OPTIONAL | SEC_ASN1_CONSTRUCTED | SEC_ASN1_EXPLICIT |
> SEC_ASN1_XTRN | SEC_ASN1_POINTER | SEC_ASN1_CONTEXT_SPECIFIC | 0,
> offsetof(SECKEYRSAPSSParams, hashAlg),
> SEC_ASN1_SUB(SECOID_AlgorithmIDTemplate) },
> { 0 }
> };
>
> SECStatus
> PSSU_EncodeDER(SECItem *dest, CK_RSA_PKCS_PSS_PARAMS *in)
> {
> SECKEYRSAPSSParams *pss_params;
> PRArenaPool *arena;
> SECItem *ret;
> unsigned int i;
>
> arena = PORT_NewArena(DER_DEFAULT_CHUNKSIZE);
> pss_params = PORT_ZAlloc(sizeof(pss_params));
That should be
pss_params = PORT_ZAlloc(sizeof(*pss_params));
or, even better
pss_params = PORT_ArenaZAlloc(arena, sizeof(*pss_params));
or, perhaps even better still
pss_params = PORT_ArenaZNew(arena, SECKEYRSAPSSParams);
> pss_params->hashAlg = PORT_ZAlloc(sizeof(SECAlgorithmID));
>
> SECOID_SetAlgorithmID(arena, pss_params->hashAlg, SEC_OID_SHA256, NULL);
>
> ret = SEC_ASN1EncodeItem(arena, NULL, pss_params,
> MY_RSAPSSParamsTemplate);
>
> PORT_FreeArena(arena, PR_FALSE);
> return SECSuccess;
> }
--
/Nelson Bolyard
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