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feat(core/prodtest): parse algorithm identifier

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This commit is contained in:
Ondřej Vejpustek 2025-06-06 15:21:43 +02:00
parent a684d6f1ed
commit be7236076f
1 changed files with 62 additions and 37 deletions
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99
core/embed/projects/prodtest/cmd/common.c
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@ -21,10 +21,12 @@
const uint8_t OID_AUTHORITY_KEY_IDENTIFIER[] = {0x06, 0x03, 0x55, 0x1d, 0x23};
// clang-format off
static const uint8_t ECDSA_WITH_SHA256[] = {
0x30, 0x0a, // a sequence of 10 bytes
static const uint8_t ECDSA_P256_WITH_SHA256[] = {
0x30, 0x13, // a sequence of 19 bytes
0x06, 0x07, // an OID of 7 bytes
0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01, // corresponds to ecPublicKey in X.509
0x06, 0x08, // an OID of 8 bytes
0x2a, 0x86, 0x48, 0xce, 0x3d, 0x04, 0x03, 0x02,
0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07, // corresponds to prime256v1 in X.509
};
static const uint8_t OID_COMMON_NAME[] = {
@ -45,6 +47,19 @@ static const uint8_t SUBJECT_COMMON_NAME[] = {
};
// clang-format on
typedef enum { ALG_ID_ECDSA_P256_WITH_SHA256 } alg_id_t;
static bool get_algorithm(DER_ITEM* alg, alg_id_t* alg_id) {
if (alg->buf.size == sizeof(ECDSA_P256_WITH_SHA256) &&
memcmp(alg->buf.data, ECDSA_P256_WITH_SHA256,
sizeof(ECDSA_P256_WITH_SHA256)) == 0) {
*alg_id = ALG_ID_ECDSA_P256_WITH_SHA256;
return true;
}
return false;
}
static bool get_cert_extensions(DER_ITEM* tbs_cert, DER_ITEM* extensions) {
// Find the certificate extensions in the tbsCertificate.
DER_ITEM cert_item = {0};
@ -171,27 +186,31 @@ static bool get_common_name(DER_ITEM* name, const uint8_t** common_name,
return true;
}
static bool verify_signature(const uint8_t* pub_key, size_t pub_key_size,
const uint8_t* sig, size_t sig_size,
const uint8_t* msg, size_t msg_size) {
// ECDSA (NIST P-256) with SHA-256
if (pub_key_size != 65) {
return false;
static bool verify_signature(alg_id_t alg_id, const uint8_t* pub_key,
size_t pub_key_size, const uint8_t* sig,
size_t sig_size, const uint8_t* msg,
size_t msg_size) {
if (alg_id == ALG_ID_ECDSA_P256_WITH_SHA256) {
if (pub_key_size != 65) {
return false;
}
uint8_t digest[SHA256_DIGEST_LENGTH] = {0};
sha256_Raw(msg, msg_size, digest);
uint8_t decoded_sig[64] = {0};
if (ecdsa_sig_from_der(sig, sig_size, decoded_sig) != 0) {
return false;
}
if (ecdsa_verify_digest(&nist256p1, pub_key, decoded_sig, digest) != 0) {
return false;
}
return true;
}
uint8_t digest[SHA256_DIGEST_LENGTH] = {0};
sha256_Raw(msg, msg_size, digest);
uint8_t decoded_sig[64] = {0};
if (ecdsa_sig_from_der(sig, sig_size, decoded_sig) != 0) {
return false;
}
if (ecdsa_verify_digest(&nist256p1, pub_key, decoded_sig, digest) != 0) {
return false;
}
return true;
return false;
}
bool check_cert_chain(cli_t* cli, const uint8_t* chain, size_t chain_size,
@ -215,6 +234,8 @@ bool check_cert_chain(cli_t* cli, const uint8_t* chain, size_t chain_size,
const uint8_t* pub_key = NULL;
size_t pub_key_size = 0;
alg_id_t alg_id = 0;
BUFFER_READER chain_reader = {0};
buffer_reader_init(&chain_reader, chain, chain_size);
int cert_count = 0;
@ -281,16 +302,24 @@ bool check_cert_chain(cli_t* cli, const uint8_t* chain, size_t chain_size,
return false;
}
// Read the algorithm
DER_ITEM alg = {0};
if (!der_read_item(&pub_key_info.buf, &alg) ||
!get_algorithm(&alg, &alg_id)) {
cli_error(cli, CLI_ERROR,
"check_device_cert_chain, reading algorithm, cert %d.",
cert_count);
return false;
}
// Read the public key.
DER_ITEM pub_key_val = {0};
uint8_t unused_bits = 0;
for (int i = 0; i < 2; ++i) {
if (!der_read_item(&pub_key_info.buf, &pub_key_val)) {
cli_error(cli, CLI_ERROR,
"check_device_cert_chain, der_read_item 6, cert %d.",
cert_count);
return false;
}
if (!der_read_item(&pub_key_info.buf, &pub_key_val)) {
cli_error(cli, CLI_ERROR,
"check_device_cert_chain, der_read_item 6, cert %d.",
cert_count);
return false;
}
if (!buffer_get(&pub_key_val.buf, &unused_bits) ||
@ -303,7 +332,7 @@ bool check_cert_chain(cli_t* cli, const uint8_t* chain, size_t chain_size,
pub_key_size = buffer_remaining(&pub_key_val.buf);
// Verify the previous signature.
if (!verify_signature(pub_key, pub_key_size, sig, sig_size, message,
if (!verify_signature(alg_id, pub_key, pub_key_size, sig, sig_size, message,
message_size)) {
cli_error(cli, CLI_ERROR,
"check_device_cert_chain, verify_signature, cert %d.",
@ -322,15 +351,11 @@ bool check_cert_chain(cli_t* cli, const uint8_t* chain, size_t chain_size,
message = tbs_cert.buf.data;
message_size = tbs_cert.buf.size;
// Read the signatureAlgorithm and ensure it matches ECDSA_WITH_SHA256.
// skip the signatureAlgorithm
DER_ITEM sig_alg = {0};
if (!der_read_item(&cert.buf, &sig_alg) ||
sig_alg.buf.size != sizeof(ECDSA_WITH_SHA256) ||
memcmp(ECDSA_WITH_SHA256, sig_alg.buf.data,
sizeof(ECDSA_WITH_SHA256)) != 0) {
if (!der_read_item(&cert.buf, &sig_alg)) {
cli_error(cli, CLI_ERROR,
"check_device_cert_chain, checking signatureAlgorithm, cert "
"%d.",
"check_device_cert_chain, der_read_item 7, cert %d.", "%d.",
cert_count);
return false;
}