1 /* 2 * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org> 3 * 4 * Permission is hereby granted, free of charge, to any person obtaining 5 * a copy of this software and associated documentation files (the 6 * "Software"), to deal in the Software without restriction, including 7 * without limitation the rights to use, copy, modify, merge, publish, 8 * distribute, sublicense, and/or sell copies of the Software, and to 9 * permit persons to whom the Software is furnished to do so, subject to 10 * the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 25 #include "inner.h" 26 27 /* see bearssl_x509.h */ 28 size_t 29 br_encode_ec_pkcs8_der(void *dest, 30 const br_ec_private_key *sk, const br_ec_public_key *pk) 31 { 32 /* 33 * ASN.1 format: 34 * 35 * OneAsymmetricKey ::= SEQUENCE { 36 * version Version, 37 * privateKeyAlgorithm PrivateKeyAlgorithmIdentifier, 38 * privateKey PrivateKey, 39 * attributes [0] Attributes OPTIONAL, 40 * ..., 41 * [[2: publicKey [1] PublicKey OPTIONAL ]], 42 * ... 43 * } 44 * 45 * We don't include attributes or public key (the public key 46 * is included in the private key value instead). The 47 * 'version' field is an INTEGER that we will set to 0 48 * (meaning 'v1', compatible with previous versions of PKCS#8). 49 * The 'privateKeyAlgorithm' structure is an AlgorithmIdentifier 50 * whose OID should be id-ecPublicKey, with, as parameters, the 51 * curve OID. The 'privateKey' is an OCTET STRING, whose value 52 * is the "raw DER" encoding of the key pair. 53 */ 54 55 /* 56 * OID id-ecPublicKey (1.2.840.10045.2.1), DER-encoded (with 57 * the tag). 58 */ 59 static const unsigned char OID_ECPUBKEY[] = { 60 0x06, 0x07, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x02, 0x01 61 }; 62 63 size_t len_version, len_privateKeyAlgorithm, len_privateKeyValue; 64 size_t len_privateKey, len_seq; 65 const unsigned char *oid; 66 67 oid = br_get_curve_OID(sk->curve); 68 if (oid == NULL) { 69 return 0; 70 } 71 len_version = 3; 72 len_privateKeyAlgorithm = 2 + sizeof OID_ECPUBKEY + 2 + oid[0]; 73 len_privateKeyValue = br_encode_ec_raw_der_inner(NULL, sk, pk, 0); 74 len_privateKey = 1 + len_of_len(len_privateKeyValue) 75 + len_privateKeyValue; 76 len_seq = len_version + len_privateKeyAlgorithm + len_privateKey; 77 78 if (dest == NULL) { 79 return 1 + len_of_len(len_seq) + len_seq; 80 } else { 81 unsigned char *buf; 82 size_t lenlen; 83 84 buf = dest; 85 *buf ++ = 0x30; /* SEQUENCE tag */ 86 lenlen = br_asn1_encode_length(buf, len_seq); 87 buf += lenlen; 88 89 /* version */ 90 *buf ++ = 0x02; 91 *buf ++ = 0x01; 92 *buf ++ = 0x00; 93 94 /* privateKeyAlgorithm */ 95 *buf ++ = 0x30; 96 *buf ++ = (sizeof OID_ECPUBKEY) + 2 + oid[0]; 97 memcpy(buf, OID_ECPUBKEY, sizeof OID_ECPUBKEY); 98 buf += sizeof OID_ECPUBKEY; 99 *buf ++ = 0x06; 100 memcpy(buf, oid, 1 + oid[0]); 101 buf += 1 + oid[0]; 102 103 /* privateKey */ 104 *buf ++ = 0x04; 105 buf += br_asn1_encode_length(buf, len_privateKeyValue); 106 br_encode_ec_raw_der_inner(buf, sk, pk, 0); 107 108 return 1 + lenlen + len_seq; 109 } 110 } 111