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DPP: Check JWS protected header alg against C-sign-key curve

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These need to be compatible for the JWS protected header signing to be
valid, so add an explicit check to confirm this.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen 2017-07-02 12:36:38 +03:00 committed by Jouni Malinen
parent d86b86d034
commit 6095b47905
1 changed files with 25 additions and 2 deletions
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27
src/common/dpp.c
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@ -3450,7 +3450,8 @@ fail:
static struct wpabuf *
dpp_parse_jws_prot_hdr(const u8 *prot_hdr, u16 prot_hdr_len,
dpp_parse_jws_prot_hdr(const struct dpp_curve_params *curve,
const u8 *prot_hdr, u16 prot_hdr_len,
const EVP_MD **ret_md)
{
struct json_token *root, *token;
@ -3490,6 +3491,12 @@ dpp_parse_jws_prot_hdr(const u8 *prot_hdr, u16 prot_hdr_len,
}
wpa_printf(MSG_DEBUG, "DPP: JWS Protected Header alg=%s",
token->string);
if (os_strcmp(token->string, curve->jws_alg) != 0) {
wpa_printf(MSG_DEBUG,
"DPP: Unexpected JWS Protected Header alg=%s (expected %s based on C-sign-key)",
token->string, curve->jws_alg);
goto fail;
}
if (os_strcmp(token->string, "ES256") == 0 ||
os_strcmp(token->string, "BS256") == 0)
*ret_md = EVP_sha256();
@ -3936,7 +3943,22 @@ dpp_process_signed_connector(struct dpp_signed_connector_info *info,
EVP_MD_CTX *md_ctx = NULL;
ECDSA_SIG *sig = NULL;
BIGNUM *r = NULL, *s = NULL;
const struct dpp_curve_params *curve;
EC_KEY *eckey;
const EC_GROUP *group;
int nid;
eckey = EVP_PKEY_get1_EC_KEY(csign_pub);
if (!eckey)
goto fail;
group = EC_KEY_get0_group(eckey);
if (!group)
goto fail;
nid = EC_GROUP_get_curve_name(group);
curve = dpp_get_curve_nid(nid);
if (!curve)
goto fail;
wpa_printf(MSG_DEBUG, "DPP: C-sign-key group: %s", curve->jwk_crv);
os_memset(info, 0, sizeof(*info));
signed_start = pos = connector;
@ -3955,7 +3977,7 @@ dpp_process_signed_connector(struct dpp_signed_connector_info *info,
wpa_hexdump_ascii(MSG_DEBUG,
"DPP: signedConnector - JWS Protected Header",
prot_hdr, prot_hdr_len);
kid = dpp_parse_jws_prot_hdr(prot_hdr, prot_hdr_len, &sign_md);
kid = dpp_parse_jws_prot_hdr(curve, prot_hdr, prot_hdr_len, &sign_md);
if (!kid)
goto fail;
if (wpabuf_len(kid) != SHA256_MAC_LEN) {
@ -4046,6 +4068,7 @@ dpp_process_signed_connector(struct dpp_signed_connector_info *info,
ret = 0;
fail:
EC_KEY_free(eckey);
EVP_MD_CTX_destroy(md_ctx);
os_free(prot_hdr);
wpabuf_free(kid);