Finish key import implementation.
This is the last bit of GoogleKeymaster that remained incomplete (for
the v0.3 functionality).
Change-Id: I27be52ae032883c004b2df21f0c7b229af512922
diff --git a/asymmetric_key.cpp b/asymmetric_key.cpp
index 297fb38..a06515b 100644
--- a/asymmetric_key.cpp
+++ b/asymmetric_key.cpp
@@ -333,6 +333,95 @@
return new_key;
}
+template <keymaster_tag_t T>
+keymaster_error_t GetOrCheckDsaParam(TypedTag<KM_BIGNUM, T> tag, BIGNUM* bn,
+ AuthorizationSet* auths) {
+ keymaster_blob_t blob;
+ if (auths->GetTagValue(tag, &blob)) {
+ // value specified, make sure it matches
+ UniquePtr<BIGNUM, BIGNUM_Delete> extracted_bn(BN_bin2bn(blob.data, blob.data_length, NULL));
+ if (extracted_bn.get() == NULL)
+ return KM_ERROR_MEMORY_ALLOCATION_FAILED;
+ if (BN_cmp(extracted_bn.get(), bn) != 0)
+ return KM_ERROR_IMPORT_PARAMETER_MISMATCH;
+ } else {
+ // value not specified, add it
+ UniquePtr<uint8_t[]> data(new uint8_t[BN_num_bytes(bn)]);
+ BN_bn2bin(bn, data.get());
+ auths->push_back(tag, data.get(), BN_num_bytes(bn));
+ }
+ return KM_ERROR_OK;
+}
+
+/* static */
+size_t DsaKey::key_size_bits(DSA* dsa_key) {
+ // Openssl provides no convenient way to get a DSA key size, but dsa_key->p is L bits long.
+ // There may be some leading zeros that mess up this calculation, but DSA key sizes are also
+ // constrained to be multiples of 64 bits. So the key size is the bit length of p rounded up to
+ // the nearest 64.
+ return ((BN_num_bytes(dsa_key->p) * 8) + 63) / 64 * 64;
+}
+
+/* static */
+DsaKey* DsaKey::ImportKey(const AuthorizationSet& key_description, EVP_PKEY* pkey,
+ const Logger& logger, keymaster_error_t* error) {
+ if (!error)
+ return NULL;
+ *error = KM_ERROR_UNKNOWN_ERROR;
+
+ UniquePtr<DSA, DSA_Delete> dsa_key(EVP_PKEY_get1_DSA(pkey));
+ if (!dsa_key.get())
+ return NULL;
+
+ AuthorizationSet authorizations(key_description);
+
+ *error = GetOrCheckDsaParam(TAG_DSA_GENERATOR, dsa_key->g, &authorizations);
+ if (*error != KM_ERROR_OK)
+ return NULL;
+
+ *error = GetOrCheckDsaParam(TAG_DSA_P, dsa_key->p, &authorizations);
+ if (*error != KM_ERROR_OK)
+ return NULL;
+
+ *error = GetOrCheckDsaParam(TAG_DSA_Q, dsa_key->q, &authorizations);
+ if (*error != KM_ERROR_OK)
+ return NULL;
+
+ // There's no convenient way to get a DSA key size, but dsa_key->p is L bits long. There may be
+ // some leading zeros that mess up this calculation, but DSA key sizes are also constrained to
+ // be multiples of 64 bits. So the bit length of p, rounded up to the nearest 64 bits, is the
+ // key size.
+ uint32_t extracted_key_size_bits = ((BN_num_bytes(dsa_key->p) * 8) + 63) / 64 * 64;
+
+ uint32_t key_size_bits;
+ if (authorizations.GetTagValue(TAG_KEY_SIZE, &key_size_bits)) {
+ // key_size_bits specified, make sure it matches the key.
+ if (key_size_bits != extracted_key_size_bits) {
+ *error = KM_ERROR_IMPORT_PARAMETER_MISMATCH;
+ return NULL;
+ }
+ } else {
+ // key_size_bits not specified, add it.
+ authorizations.push_back(TAG_KEY_SIZE, extracted_key_size_bits);
+ }
+
+ keymaster_algorithm_t algorithm;
+ if (authorizations.GetTagValue(TAG_ALGORITHM, &algorithm)) {
+ if (algorithm != KM_ALGORITHM_DSA) {
+ *error = KM_ERROR_IMPORT_PARAMETER_MISMATCH;
+ return NULL;
+ }
+ } else {
+ authorizations.push_back(TAG_ALGORITHM, KM_ALGORITHM_DSA);
+ }
+
+ // Don't bother with the other parameters. If the necessary padding, digest, purpose, etc. are
+ // missing, the error will be diagnosed when the key is used (when auth checking is
+ // implemented).
+ *error = KM_ERROR_OK;
+ return new DsaKey(dsa_key.release(), authorizations, logger);
+}
+
DsaKey::DsaKey(const KeyBlob& blob, const Logger& logger, keymaster_error_t* error)
: AsymmetricKey(blob, logger) {
if (error)
@@ -407,6 +496,53 @@
}
/* static */
+EcdsaKey* EcdsaKey::ImportKey(const AuthorizationSet& key_description, EVP_PKEY* pkey,
+ const Logger& logger, keymaster_error_t* error) {
+ if (!error)
+ return NULL;
+ *error = KM_ERROR_UNKNOWN_ERROR;
+
+ UniquePtr<EC_KEY, ECDSA_Delete> ecdsa_key(EVP_PKEY_get1_EC_KEY(pkey));
+ if (!ecdsa_key.get())
+ return NULL;
+
+ AuthorizationSet authorizations(key_description);
+
+ size_t extracted_key_size_bits;
+ *error = get_group_size(*EC_KEY_get0_group(ecdsa_key.get()), &extracted_key_size_bits);
+ if (*error != KM_ERROR_OK)
+ return NULL;
+
+ uint32_t key_size_bits;
+ if (authorizations.GetTagValue(TAG_KEY_SIZE, &key_size_bits)) {
+ // key_size_bits specified, make sure it matches the key.
+ if (key_size_bits != extracted_key_size_bits) {
+ *error = KM_ERROR_IMPORT_PARAMETER_MISMATCH;
+ return NULL;
+ }
+ } else {
+ // key_size_bits not specified, add it.
+ authorizations.push_back(TAG_KEY_SIZE, extracted_key_size_bits);
+ }
+
+ keymaster_algorithm_t algorithm;
+ if (authorizations.GetTagValue(TAG_ALGORITHM, &algorithm)) {
+ if (algorithm != KM_ALGORITHM_ECDSA) {
+ *error = KM_ERROR_IMPORT_PARAMETER_MISMATCH;
+ return NULL;
+ }
+ } else {
+ authorizations.push_back(TAG_ALGORITHM, KM_ALGORITHM_ECDSA);
+ }
+
+ // Don't bother with the other parameters. If the necessary padding, digest, purpose, etc. are
+ // missing, the error will be diagnosed when the key is used (when auth checking is
+ // implemented).
+ *error = KM_ERROR_OK;
+ return new EcdsaKey(ecdsa_key.release(), authorizations, logger);
+}
+
+/* static */
EC_GROUP* EcdsaKey::choose_group(size_t key_size_bits) {
switch (key_size_bits) {
case 192:
@@ -430,6 +566,30 @@
}
}
+/* static */
+keymaster_error_t EcdsaKey::get_group_size(const EC_GROUP& group, size_t* key_size_bits) {
+ switch (EC_GROUP_get_curve_name(&group)) {
+ case NID_X9_62_prime192v1:
+ *key_size_bits = 192;
+ break;
+ case NID_secp224r1:
+ *key_size_bits = 224;
+ break;
+ case NID_X9_62_prime256v1:
+ *key_size_bits = 256;
+ break;
+ case NID_secp384r1:
+ *key_size_bits = 384;
+ break;
+ case NID_secp521r1:
+ *key_size_bits = 521;
+ break;
+ default:
+ return KM_ERROR_UNSUPPORTED_EC_FIELD;
+ }
+ return KM_ERROR_OK;
+}
+
EcdsaKey::EcdsaKey(const KeyBlob& blob, const Logger& logger, keymaster_error_t* error)
: AsymmetricKey(blob, logger) {
if (error)