Added support code for RSA and EC key encoding (including reconstruction of all publi...

[BearSSL] / src / x509 / encode_ec_pk8der.c

diff --git a/src/x509/encode_ec_pk8der.c b/src/x509/encode_ec_pk8der.c
new file mode 100644 (file)
index 0000000..53717ce
--- /dev/null
+++ b/src/x509/encode_ec_pk8der.c
@@ -0,0 +1,110 @@
+/*
+ * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining 
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be 
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/* see bearssl_x509.h */
+size_t
+br_encode_ec_pkcs8_der(void *dest,
+       const br_ec_private_key *sk, const br_ec_public_key *pk)
+{
+       /*
+        * ASN.1 format:
+        *
+        *   OneAsymmetricKey ::= SEQUENCE {
+        *     version                   Version,
+        *     privateKeyAlgorithm       PrivateKeyAlgorithmIdentifier,
+        *     privateKey                PrivateKey,
+        *     attributes            [0] Attributes OPTIONAL,
+        *     ...,
+        *     [[2: publicKey        [1] PublicKey OPTIONAL ]],
+        *     ...
+        *   }
+        *
+        * We don't include attributes or public key (the public key
+        * is included in the private key value instead). The
+        * 'version' field is an INTEGER that we will set to 0
+        * (meaning 'v1', compatible with previous versions of PKCS#8).
+        * The 'privateKeyAlgorithm' structure is an AlgorithmIdentifier
+        * whose OID should be id-ecPublicKey, with, as parameters, the
+        * curve OID. The 'privateKey' is an OCTET STRING, whose value
+        * is the "raw DER" encoding of the key pair.
+        */
+
+       /*
+        * OID id-ecPublicKey (1.2.840.10045.2.1), DER-encoded (with
+        * the tag).
+        */
+       static const unsigned char OID_ECPUBKEY[] = {
+               0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01
+       };
+
+       size_t len_version, len_privateKeyAlgorithm, len_privateKeyValue;
+       size_t len_privateKey, len_seq;
+       const unsigned char *oid;
+
+       oid = br_get_curve_OID(sk->curve);
+       if (oid == NULL) {
+               return 0;
+       }
+       len_version = 3;
+       len_privateKeyAlgorithm = 2 + sizeof OID_ECPUBKEY + 2 + oid[0];
+       len_privateKeyValue = br_encode_ec_raw_der_inner(NULL, sk, pk, 0);
+       len_privateKey = 1 + len_of_len(len_privateKeyValue)
+               + len_privateKeyValue;
+       len_seq = len_version + len_privateKeyAlgorithm + len_privateKey;
+
+       if (dest == NULL) {
+               return 1 + len_of_len(len_seq) + len_seq;
+       } else {
+               unsigned char *buf;
+               size_t lenlen;
+
+               buf = dest;
+               *buf ++ = 0x30;  /* SEQUENCE tag */
+               lenlen = br_asn1_encode_length(buf, len_seq);
+               buf += lenlen;
+
+               /* version */
+               *buf ++ = 0x02;
+               *buf ++ = 0x01;
+               *buf ++ = 0x00;
+
+               /* privateKeyAlgorithm */
+               *buf ++ = 0x30;
+               *buf ++ = (sizeof OID_ECPUBKEY) + 2 + oid[0];
+               memcpy(buf, OID_ECPUBKEY, sizeof OID_ECPUBKEY);
+               buf += sizeof OID_ECPUBKEY;
+               *buf ++ = 0x06;
+               memcpy(buf, oid, 1 + oid[0]);
+               buf += 1 + oid[0];
+
+               /* privateKey */
+               *buf ++ = 0x04;
+               buf += br_asn1_encode_length(buf, len_privateKeyValue);
+               br_encode_ec_raw_der_inner(buf, sk, pk, 0);
+
+               return 1 + lenlen + len_seq;
+       }
+}