* [PATCH v2 01/10] dpp-util: add dpp_point_from_asn1()
@ 2022-01-20 23:44 James Prestwood
0 siblings, 0 replies; 2+ messages in thread
From: James Prestwood @ 2022-01-20 23:44 UTC (permalink / raw)
To: iwd
[-- Attachment #1: Type: text/plain, Size: 2761 bytes --]
Given an ASN1 blob of the right form, parse and create
an l_ecc_point object. The form used is specific to DPP
hence why this isn't general purpose and put into dpp-util.
---
src/dpp-util.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
src/dpp-util.h | 1 +
2 files changed, 70 insertions(+)
diff --git a/src/dpp-util.c b/src/dpp-util.c
index 4823b2f0..4a5bd046 100644
--- a/src/dpp-util.c
+++ b/src/dpp-util.c
@@ -796,3 +796,72 @@ uint8_t *dpp_point_to_asn1(const struct l_ecc_point *p, size_t *len_out)
return asn1;
}
+
+/*
+ * Only checking for the ASN.1 form:
+ *
+ * SEQUENCE {
+ * SEQUENCE {
+ * OBJECT IDENTIFIER ecPublicKey
+ * OBJECT IDENTIFIER key type (p256/p384)
+ * }
+ * BITSTRING (key data)
+ * }
+ */
+struct l_ecc_point *dpp_point_from_asn1(const uint8_t *asn1, size_t len)
+{
+
+ const uint8_t *outer_seq;
+ size_t outer_len;
+ const uint8_t *inner_seq;
+ size_t inner_len;
+ const uint8_t *elem;
+ const uint8_t *key_data;
+ size_t elen = 0;
+ uint8_t tag;
+ unsigned int curve_num;
+ const struct l_ecc_curve *curve;
+
+ /* SEQUENCE */
+ outer_seq = asn1_der_find_elem(asn1, len, 0, &tag, &outer_len);
+ if (!outer_seq || tag != ASN1_ID_SEQUENCE)
+ return NULL;
+
+ /* SEQUENCE */
+ inner_seq = asn1_der_find_elem(outer_seq, outer_len, 0, &tag, &inner_len);
+ if (!inner_seq || tag != ASN1_ID_SEQUENCE)
+ return NULL;
+
+ /* OBJECT IDENTIFIER (ecPublicKey) */
+ elem = asn1_der_find_elem(inner_seq, inner_len, 0, &tag, &elen);
+ if (!elem || tag != ASN1_ID_OID)
+ return NULL;
+
+ /* Check that this OID is ecPublicKey */
+ if (!asn1_oid_eq(&ec_oid, elen, elem))
+ return NULL;
+
+ elem = asn1_der_find_elem(inner_seq, inner_len, 1, &tag, &elen);
+ if (!elem || tag != ASN1_ID_OID)
+ return NULL;
+
+ /* Check if ELL supports this curve */
+ if (asn1_oid_eq(&ec_p256_oid, elen, elem))
+ curve_num = 19;
+ else if (asn1_oid_eq(&ec_p384_oid, elen, elem))
+ curve_num = 20;
+ else
+ return NULL;
+
+ curve = l_ecc_curve_from_ike_group(curve_num);
+ if (!curve)
+ return NULL;
+
+ /* BITSTRING */
+ key_data = asn1_der_find_elem(outer_seq, outer_len, 1, &tag, &elen);
+ if (!key_data || tag != ASN1_ID_BIT_STRING || elen > 2)
+ return NULL;
+
+ return l_ecc_point_from_data(curve, key_data[1],
+ key_data + 2, elen - 2);
+}
diff --git a/src/dpp-util.h b/src/dpp-util.h
index 84d33656..82535ff8 100644
--- a/src/dpp-util.h
+++ b/src/dpp-util.h
@@ -167,3 +167,4 @@ bool dpp_derive_ke(const uint8_t *i_nonce, const uint8_t *r_nonce,
void *ke);
uint8_t *dpp_point_to_asn1(const struct l_ecc_point *p, size_t *len_out);
+struct l_ecc_point *dpp_point_from_asn1(const uint8_t *asn1, size_t len);
--
2.31.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2 01/10] dpp-util: add dpp_point_from_asn1()
@ 2022-01-21 16:55 Denis Kenzior
0 siblings, 0 replies; 2+ messages in thread
From: Denis Kenzior @ 2022-01-21 16:55 UTC (permalink / raw)
To: iwd
[-- Attachment #1: Type: text/plain, Size: 632 bytes --]
Hi James,
On 1/20/22 17:44, James Prestwood wrote:
> Given an ASN1 blob of the right form, parse and create
> an l_ecc_point object. The form used is specific to DPP
> hence why this isn't general purpose and put into dpp-util.
> ---
> src/dpp-util.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
> src/dpp-util.h | 1 +
> 2 files changed, 70 insertions(+)
>
<snip>
> + /* BITSTRING */
> + key_data = asn1_der_find_elem(outer_seq, outer_len, 1, &tag, &elen);
> + if (!key_data || tag != ASN1_ID_BIT_STRING || elen > 2)
< 2?
also you have a line > 80 chars in this patch.
Regards,
-Denis
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2022-01-21 16:55 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-01-20 23:44 [PATCH v2 01/10] dpp-util: add dpp_point_from_asn1() James Prestwood
2022-01-21 16:55 Denis Kenzior
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.