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TLS: Parse and validate BasicOCSPResponse

Browse source 
This adds the next step in completing TLS client support for OCSP
stapling. The BasicOCSPResponse is parsed, a signing certificate is
found, and the signature is verified. The actual sequence of OCSP
responses (SignleResponse) is not yet processed in this commit.

Signed-off-by: Jouni Malinen <j@w1.fi>
This commit is contained in:
Jouni Malinen 2015-12-17 00:38:40 +02:00
parent 8e416cecdb
commit af4eba16ce
3 changed files with 387 additions and 42 deletions
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320
src/tls/tlsv1_client_ocsp.c
View file

@ -10,7 +10,9 @@
#include "common.h"
#include "crypto/tls.h"
#include "crypto/sha1.h"
#include "asn1.h"
#include "x509v3.h"
#include "tlsv1_common.h"
#include "tlsv1_record.h"
#include "tlsv1_client.h"
@ -45,12 +47,44 @@ static int is_oid_basic_ocsp_resp(struct asn1_oid *oid)
}
static int ocsp_responder_id_match(struct x509_certificate *signer,
struct x509_name *name, const u8 *key_hash)
{
if (key_hash) {
u8 hash[SHA1_MAC_LEN];
const u8 *addr[1] = { signer->public_key };
size_t len[1] = { signer->public_key_len };
if (sha1_vector(1, addr, len, hash) < 0)
return 0;
return os_memcmp(hash, key_hash, SHA1_MAC_LEN) == 0;
}
return x509_name_compare(&signer->subject, name) == 0;
}
static enum tls_ocsp_result
tls_process_basic_ocsp_response(struct tlsv1_client *conn, const u8 *resp,
size_t len)
{
struct asn1_hdr hdr;
const u8 *pos, *end;
const u8 *resp_data, *sign_value, *key_hash = NULL, *responses;
const u8 *resp_data_signed;
size_t resp_data_len, sign_value_len, responses_len;
size_t resp_data_signed_len;
struct x509_algorithm_identifier alg;
struct x509_certificate *certs = NULL, *last_cert = NULL;
struct x509_certificate *issuer, *signer;
struct x509_name name; /* used if key_hash == NULL */
char buf[100];
os_time_t produced_at;
wpa_hexdump(MSG_MSGDUMP, "OCSP: BasicOCSPResponse", resp, len);
os_memset(&name, 0, sizeof(name));
/*
* RFC 6960, 4.2.1:
* BasicOCSPResponse ::= SEQUENCE {
@ -60,8 +94,292 @@ tls_process_basic_ocsp_response(struct tlsv1_client *conn, const u8 *resp,
* certs [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL }
*/
/* TODO */
if (asn1_get_next(resp, len, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_SEQUENCE) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected SEQUENCE (BasicOCSPResponse) - found class %d tag 0x%x",
hdr.class, hdr.tag);
return TLS_OCSP_INVALID;
}
pos = hdr.payload;
end = hdr.payload + hdr.length;
/* ResponseData ::= SEQUENCE */
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_SEQUENCE) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected SEQUENCE (ResponseData) - found class %d tag 0x%x",
hdr.class, hdr.tag);
return TLS_OCSP_INVALID;
}
resp_data = hdr.payload;
resp_data_len = hdr.length;
resp_data_signed = pos;
pos = hdr.payload + hdr.length;
resp_data_signed_len = pos - resp_data_signed;
/* signatureAlgorithm AlgorithmIdentifier */
if (x509_parse_algorithm_identifier(pos, end - pos, &alg, &pos))
return TLS_OCSP_INVALID;
/* signature BIT STRING */
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_BITSTRING) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected BITSTRING (signature) - found class %d tag 0x%x",
hdr.class, hdr.tag);
return TLS_OCSP_INVALID;
}
if (hdr.length < 1)
return TLS_OCSP_INVALID;
pos = hdr.payload;
if (*pos) {
wpa_printf(MSG_DEBUG, "OCSP: BITSTRING - %d unused bits", *pos);
/* PKCS #1 v1.5 10.2.1:
* It is an error if the length in bits of the signature S is
* not a multiple of eight.
*/
return TLS_OCSP_INVALID;
}
sign_value = pos + 1;
sign_value_len = hdr.length - 1;
pos += hdr.length;
wpa_hexdump(MSG_MSGDUMP, "OCSP: signature", sign_value, sign_value_len);
/* certs [0] EXPLICIT SEQUENCE OF Certificate OPTIONAL */
if (pos < end) {
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC ||
hdr.tag != 0) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected [0] EXPLICIT (certs) - found class %d tag 0x%x",
hdr.class, hdr.tag);
return TLS_OCSP_INVALID;
}
wpa_hexdump(MSG_MSGDUMP, "OCSP: certs",
hdr.payload, hdr.length);
pos = hdr.payload;
end = hdr.payload + hdr.length;
while (pos < end) {
struct x509_certificate *cert;
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_SEQUENCE) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected SEQUENCE (Certificate) - found class %d tag 0x%x",
hdr.class, hdr.tag);
goto fail;
}
cert = x509_certificate_parse(hdr.payload, hdr.length);
if (!cert)
goto fail;
if (last_cert) {
last_cert->next = cert;
last_cert = cert;
} else {
last_cert = certs = cert;
}
pos = hdr.payload + hdr.length;
}
}
/*
* ResponseData ::= SEQUENCE {
* version [0] EXPLICIT Version DEFAULT v1,
* responderID ResponderID,
* producedAt GeneralizedTime,
* responses SEQUENCE OF SingleResponse,
* responseExtensions [1] EXPLICIT Extensions OPTIONAL }
*/
pos = resp_data;
end = resp_data + resp_data_len;
wpa_hexdump(MSG_MSGDUMP, "OCSP: ResponseData", pos, end - pos);
/*
* version [0] EXPLICIT Version DEFAULT v1
* Version ::= INTEGER { v1(0) }
*/
if (asn1_get_next(pos, end - pos, &hdr) < 0 &&
hdr.class == ASN1_CLASS_CONTEXT_SPECIFIC &&
hdr.tag == 0) {
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_INTEGER ||
hdr.length != 1) {
wpa_printf(MSG_DEBUG,
"OCSP: No INTEGER (len=1) tag found for version field - found class %d tag 0x%x length %d",
hdr.class, hdr.tag, hdr.length);
goto fail;
}
wpa_printf(MSG_DEBUG, "OCSP: ResponseData version %u",
hdr.payload[0]);
if (hdr.payload[0] != 0) {
wpa_printf(MSG_DEBUG,
"OCSP: Unsupported ResponseData version %u",
hdr.payload[0]);
goto no_resp;
}
pos = hdr.payload + hdr.length;
} else {
wpa_printf(MSG_DEBUG,
"OCSP: Default ResponseData version (v1)");
}
/*
* ResponderID ::= CHOICE {
* byName [1] Name,
* byKey [2] KeyHash }
*/
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_CONTEXT_SPECIFIC) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected CHOICE (ResponderID) - found class %d tag 0x%x",
hdr.class, hdr.tag);
goto fail;
}
if (hdr.tag == 1) {
/* Name */
if (x509_parse_name(hdr.payload, hdr.length, &name, &pos) < 0)
goto fail;
x509_name_string(&name, buf, sizeof(buf));
wpa_printf(MSG_DEBUG, "OCSP: ResponderID byName Name: %s", buf);
} else if (hdr.tag == 2) {
/* KeyHash ::= OCTET STRING */
if (asn1_get_next(hdr.payload, hdr.length, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_OCTETSTRING) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected OCTET STRING (KeyHash) - found class %d tag 0x%x",
hdr.class, hdr.tag);
goto fail;
}
key_hash = hdr.payload;
wpa_hexdump(MSG_DEBUG, "OCSP: ResponderID byKey KeyHash",
key_hash, hdr.length);
if (hdr.length != SHA1_MAC_LEN) {
wpa_printf(MSG_DEBUG,
"OCSP: Unexpected byKey KeyHash length %u - expected %u for SHA-1",
hdr.length, SHA1_MAC_LEN);
goto fail;
}
pos = hdr.payload + hdr.length;
} else {
wpa_printf(MSG_DEBUG, "OCSP: Unexpected ResponderID CHOICE %u",
hdr.tag);
goto fail;
}
/* producedAt GeneralizedTime */
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_GENERALIZEDTIME ||
x509_parse_time(hdr.payload, hdr.length, hdr.tag,
&produced_at) < 0) {
wpa_printf(MSG_DEBUG, "OCSP: Failed to parse producedAt");
goto fail;
}
wpa_printf(MSG_DEBUG, "OCSP: producedAt %lu",
(unsigned long) produced_at);
pos = hdr.payload + hdr.length;
/* responses SEQUENCE OF SingleResponse */
if (asn1_get_next(pos, end - pos, &hdr) < 0 ||
hdr.class != ASN1_CLASS_UNIVERSAL ||
hdr.tag != ASN1_TAG_SEQUENCE) {
wpa_printf(MSG_DEBUG,
"OCSP: Expected SEQUENCE (responses) - found class %d tag 0x%x",
hdr.class, hdr.tag);
goto fail;
}
responses = hdr.payload;
responses_len = hdr.length;
wpa_hexdump(MSG_MSGDUMP, "OCSP: responses", responses, responses_len);
pos = hdr.payload + hdr.length;
if (pos < end) {
/* responseExtensions [1] EXPLICIT Extensions OPTIONAL */
wpa_hexdump(MSG_MSGDUMP, "OCSP: responseExtensions",
pos, end - pos);
/* Ignore for now. */
}
if (!conn->server_cert) {
wpa_printf(MSG_DEBUG,
"OCSP: Server certificate not known - cannot check OCSP response");
goto no_resp;
}
if (conn->server_cert->next) {
/* Issuer has already been verified in the chain */
issuer = conn->server_cert->next;
} else {
/* Find issuer from the set of trusted certificates */
for (issuer = conn->cred ? conn->cred->trusted_certs : NULL;
issuer; issuer = issuer->next) {
if (x509_name_compare(&conn->server_cert->issuer,
&issuer->subject) == 0)
break;
}
}
if (!issuer) {
wpa_printf(MSG_DEBUG,
"OCSP: Server certificate issuer not known - cannot check OCSP response");
goto no_resp;
}
if (ocsp_responder_id_match(issuer, &name, key_hash)) {
wpa_printf(MSG_DEBUG,
"OCSP: Server certificate issuer certificate matches ResponderID");
signer = issuer;
} else {
for (signer = certs; signer; signer = signer->next) {
if (!ocsp_responder_id_match(signer, &name, key_hash) ||
x509_name_compare(&conn->server_cert->issuer,
&issuer->subject) != 0 ||
!(signer->ext_key_usage &
X509_EXT_KEY_USAGE_OCSP) ||
x509_certificate_check_signature(issuer, signer) <
0)
continue;
wpa_printf(MSG_DEBUG,
"OCSP: An extra certificate from the response matches ResponderID and is trusted as an OCSP signer");
break;
}
if (!signer) {
wpa_printf(MSG_DEBUG,
"OCSP: Could not find OCSP signer certificate");
goto no_resp;
}
}
x509_free_name(&name);
os_memset(&name, 0, sizeof(name));
x509_certificate_chain_free(certs);
certs = NULL;
if (x509_check_signature(signer, &alg, sign_value, sign_value_len,
resp_data_signed, resp_data_signed_len) < 0) {
wpa_printf(MSG_DEBUG, "OCSP: Invalid signature");
return TLS_OCSP_INVALID;
}
/* TODO: Check responses */
no_resp:
x509_free_name(&name);
x509_certificate_chain_free(certs);
return TLS_OCSP_NO_RESPONSE;
fail:
x509_free_name(&name);
x509_certificate_chain_free(certs);
return TLS_OCSP_INVALID;
}

97
src/tls/x509v3.c
View file

@ -1,6 +1,6 @@
/*
* X.509v3 certificate parsing and processing (RFC 3280 profile)
* Copyright (c) 2006-2011, Jouni Malinen <j@w1.fi>
* Copyright (c) 2006-2015, Jouni Malinen <j@w1.fi>
*
* This software may be distributed under the terms of the BSD license.
* See README for more details.
@ -14,7 +14,7 @@
#include "x509v3.h"
static void x509_free_name(struct x509_name *name)
void x509_free_name(struct x509_name *name)
{
size_t i;
@ -177,9 +177,9 @@ int x509_name_compare(struct x509_name *a, struct x509_name *b)
}
static int x509_parse_algorithm_identifier(
const u8 *buf, size_t len,
struct x509_algorithm_identifier *id, const u8 **next)
int x509_parse_algorithm_identifier(const u8 *buf, size_t len,
struct x509_algorithm_identifier *id,
const u8 **next)
{
struct asn1_hdr hdr;
const u8 *pos, *end;
@ -288,8 +288,8 @@ static int x509_parse_public_key(const u8 *buf, size_t len,
}
static int x509_parse_name(const u8 *buf, size_t len, struct x509_name *name,
const u8 **next)
int x509_parse_name(const u8 *buf, size_t len, struct x509_name *name,
const u8 **next)
{
struct asn1_hdr hdr;
const u8 *pos, *end, *set_pos, *set_end, *seq_pos, *seq_end;
@ -536,8 +536,7 @@ done:
}
static int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag,
os_time_t *val)
int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val)
{
const char *pos;
int year, month, day, hour, min, sec;
@ -1122,6 +1121,15 @@ static int x509_id_kp_client_auth_oid(struct asn1_oid *oid)
}
static int x509_id_kp_ocsp_oid(struct asn1_oid *oid)
{
/* id-kp */
return oid->len == 9 &&
x509_id_kp_oid(oid) &&
oid->oid[8] == 9 /* id-kp-OCSPSigning */;
}
static int x509_parse_ext_ext_key_usage(struct x509_certificate *cert,
const u8 *pos, size_t len)
{
@ -1164,6 +1172,9 @@ static int x509_parse_ext_ext_key_usage(struct x509_certificate *cert,
} else if (x509_id_kp_client_auth_oid(&oid)) {
os_strlcpy(buf, "id-kp-clientAuth", sizeof(buf));
cert->ext_key_usage |= X509_EXT_KEY_USAGE_CLIENT_AUTH;
} else if (x509_id_kp_ocsp_oid(&oid)) {
os_strlcpy(buf, "id-kp-OCSPSigning", sizeof(buf));
cert->ext_key_usage |= X509_EXT_KEY_USAGE_OCSP;
} else {
asn1_oid_to_str(&oid, buf, sizeof(buf));
}
@ -1704,6 +1715,17 @@ struct x509_certificate * x509_certificate_parse(const u8 *buf, size_t len)
*/
int x509_certificate_check_signature(struct x509_certificate *issuer,
struct x509_certificate *cert)
{
return x509_check_signature(issuer, &cert->signature,
cert->sign_value, cert->sign_value_len,
cert->tbs_cert_start, cert->tbs_cert_len);
}
int x509_check_signature(struct x509_certificate *issuer,
struct x509_algorithm_identifier *signature,
const u8 *sign_value, size_t sign_value_len,
const u8 *signed_data, size_t signed_data_len)
{
struct crypto_public_key *pk;
u8 *data;
@ -1713,10 +1735,12 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
struct asn1_oid oid;
u8 hash[64];
size_t hash_len;
const u8 *addr[1] = { signed_data };
size_t len[1] = { signed_data_len };
if (!x509_pkcs_oid(&cert->signature.oid) ||
cert->signature.oid.len != 7 ||
cert->signature.oid.oid[5] != 1 /* pkcs-1 */) {
if (!x509_pkcs_oid(&signature->oid) ||
signature->oid.len != 7 ||
signature->oid.oid[5] != 1 /* pkcs-1 */) {
wpa_printf(MSG_DEBUG, "X509: Unrecognized signature "
"algorithm");
return -1;
@ -1727,15 +1751,15 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
if (pk == NULL)
return -1;
data_len = cert->sign_value_len;
data_len = sign_value_len;
data = os_malloc(data_len);
if (data == NULL) {
crypto_public_key_free(pk);
return -1;
}
if (crypto_public_key_decrypt_pkcs1(pk, cert->sign_value,
cert->sign_value_len, data,
if (crypto_public_key_decrypt_pkcs1(pk, sign_value,
sign_value_len, data,
&data_len) < 0) {
wpa_printf(MSG_DEBUG, "X509: Failed to decrypt signature");
crypto_public_key_free(pk);
@ -1798,12 +1822,11 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
}
if (x509_sha1_oid(&oid)) {
if (cert->signature.oid.oid[6] !=
5 /* sha-1WithRSAEncryption */) {
if (signature->oid.oid[6] != 5 /* sha-1WithRSAEncryption */) {
wpa_printf(MSG_DEBUG, "X509: digestAlgorithm SHA1 "
"does not match with certificate "
"signatureAlgorithm (%lu)",
cert->signature.oid.oid[6]);
signature->oid.oid[6]);
os_free(data);
return -1;
}
@ -1811,12 +1834,12 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
}
if (x509_sha256_oid(&oid)) {
if (cert->signature.oid.oid[6] !=
if (signature->oid.oid[6] !=
11 /* sha2561WithRSAEncryption */) {
wpa_printf(MSG_DEBUG, "X509: digestAlgorithm SHA256 "
"does not match with certificate "
"signatureAlgorithm (%lu)",
cert->signature.oid.oid[6]);
signature->oid.oid[6]);
os_free(data);
return -1;
}
@ -1824,12 +1847,11 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
}
if (x509_sha384_oid(&oid)) {
if (cert->signature.oid.oid[6] !=
12 /* sha384WithRSAEncryption */) {
if (signature->oid.oid[6] != 12 /* sha384WithRSAEncryption */) {
wpa_printf(MSG_DEBUG, "X509: digestAlgorithm SHA384 "
"does not match with certificate "
"signatureAlgorithm (%lu)",
cert->signature.oid.oid[6]);
signature->oid.oid[6]);
os_free(data);
return -1;
}
@ -1837,12 +1859,11 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
}
if (x509_sha512_oid(&oid)) {
if (cert->signature.oid.oid[6] !=
13 /* sha512WithRSAEncryption */) {
if (signature->oid.oid[6] != 13 /* sha512WithRSAEncryption */) {
wpa_printf(MSG_DEBUG, "X509: digestAlgorithm SHA512 "
"does not match with certificate "
"signatureAlgorithm (%lu)",
cert->signature.oid.oid[6]);
signature->oid.oid[6]);
os_free(data);
return -1;
}
@ -1856,12 +1877,11 @@ int x509_certificate_check_signature(struct x509_certificate *issuer,
}
switch (oid.oid[5]) {
case 5: /* md5 */
if (cert->signature.oid.oid[6] != 4 /* md5WithRSAEncryption */)
{
if (signature->oid.oid[6] != 4 /* md5WithRSAEncryption */) {
wpa_printf(MSG_DEBUG, "X509: digestAlgorithm MD5 does "
"not match with certificate "
"signatureAlgorithm (%lu)",
cert->signature.oid.oid[6]);
signature->oid.oid[6]);
os_free(data);
return -1;
}
@ -1892,38 +1912,33 @@ skip_digest_oid:
wpa_hexdump(MSG_MSGDUMP, "X509: Decrypted Digest",
hdr.payload, hdr.length);
switch (cert->signature.oid.oid[6]) {
switch (signature->oid.oid[6]) {
case 4: /* md5WithRSAEncryption */
md5_vector(1, &cert->tbs_cert_start, &cert->tbs_cert_len,
hash);
md5_vector(1, addr, len, hash);
hash_len = 16;
wpa_hexdump(MSG_MSGDUMP, "X509: Certificate hash (MD5)",
hash, hash_len);
break;
case 5: /* sha-1WithRSAEncryption */
sha1_vector(1, &cert->tbs_cert_start, &cert->tbs_cert_len,
hash);
sha1_vector(1, addr, len, hash);
hash_len = 20;
wpa_hexdump(MSG_MSGDUMP, "X509: Certificate hash (SHA1)",
hash, hash_len);
break;
case 11: /* sha256WithRSAEncryption */
sha256_vector(1, &cert->tbs_cert_start, &cert->tbs_cert_len,
hash);
sha256_vector(1, addr, len, hash);
hash_len = 32;
wpa_hexdump(MSG_MSGDUMP, "X509: Certificate hash (SHA256)",
hash, hash_len);
break;
case 12: /* sha384WithRSAEncryption */
sha384_vector(1, &cert->tbs_cert_start, &cert->tbs_cert_len,
hash);
sha384_vector(1, addr, len, hash);
hash_len = 48;
wpa_hexdump(MSG_MSGDUMP, "X509: Certificate hash (SHA384)",
hash, hash_len);
break;
case 13: /* sha512WithRSAEncryption */
sha512_vector(1, &cert->tbs_cert_start, &cert->tbs_cert_len,
hash);
sha512_vector(1, addr, len, hash);
hash_len = 64;
wpa_hexdump(MSG_MSGDUMP, "X509: Certificate hash (SHA512)",
hash, hash_len);
@ -1931,7 +1946,7 @@ skip_digest_oid:
case 2: /* md2WithRSAEncryption */
default:
wpa_printf(MSG_INFO, "X509: Unsupported certificate signature "
"algorithm (%lu)", cert->signature.oid.oid[6]);
"algorithm (%lu)", signature->oid.oid[6]);
os_free(data);
return -1;
}

12
src/tls/x509v3.h
View file

@ -91,6 +91,7 @@ struct x509_certificate {
#define X509_EXT_KEY_USAGE_ANY (1 << 0)
#define X509_EXT_KEY_USAGE_SERVER_AUTH (1 << 1)
#define X509_EXT_KEY_USAGE_CLIENT_AUTH (1 << 2)
#define X509_EXT_KEY_USAGE_OCSP (1 << 3)
/*
* The DER format certificate follows struct x509_certificate. These
@ -113,10 +114,21 @@ enum {
};
void x509_certificate_free(struct x509_certificate *cert);
int x509_parse_algorithm_identifier(const u8 *buf, size_t len,
struct x509_algorithm_identifier *id,
const u8 **next);
int x509_parse_name(const u8 *buf, size_t len, struct x509_name *name,
const u8 **next);
int x509_parse_time(const u8 *buf, size_t len, u8 asn1_tag, os_time_t *val);
struct x509_certificate * x509_certificate_parse(const u8 *buf, size_t len);
void x509_free_name(struct x509_name *name);
void x509_name_string(struct x509_name *name, char *buf, size_t len);
int x509_name_compare(struct x509_name *a, struct x509_name *b);
void x509_certificate_chain_free(struct x509_certificate *cert);
int x509_check_signature(struct x509_certificate *issuer,
struct x509_algorithm_identifier *signature,
const u8 *sign_value, size_t sign_value_len,
const u8 *signed_data, size_t signed_data_len);
int x509_certificate_check_signature(struct x509_certificate *issuer,
struct x509_certificate *cert);
int x509_certificate_chain_validate(struct x509_certificate *trusted,