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_rsa_pkcs8_der(void *dest, const br_rsa_private_key *sk, 30 const br_rsa_public_key *pk, const void *d, size_t dlen) 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 'version' field 46 * is an INTEGER that we will set to 0 (meaning 'v1', compatible 47 * with previous versions of PKCS#8). The 'privateKeyAlgorithm' 48 * structure is an AlgorithmIdentifier whose OID should be 49 * rsaEncryption, with NULL parameters. The 'privateKey' is an 50 * OCTET STRING, whose value is the "raw DER" encoding of the 51 * key pair. 52 * 53 * Since the private key value comes last, this function really 54 * adds a header, which is mostly fixed (only some lengths have 55 * to be modified. 56 */ 57 58 /* 59 * Concatenation of: 60 * - DER encoding of an INTEGER of value 0 (the 'version' field) 61 * - DER encoding of a PrivateKeyAlgorithmIdentifier that uses 62 * the rsaEncryption OID, and NULL parameters 63 * - An OCTET STRING tag 64 */ 65 static const unsigned char PK8_HEAD[] = { 66 0x02, 0x01, 0x00, 67 0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 68 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00, 69 0x04 70 }; 71 72 size_t len_raw, len_seq; 73 74 len_raw = br_encode_rsa_raw_der(NULL, sk, pk, d, dlen); 75 len_seq = (sizeof PK8_HEAD) + len_of_len(len_raw) + len_raw; 76 if (dest == NULL) { 77 return 1 + len_of_len(len_seq) + len_seq; 78 } else { 79 unsigned char *buf; 80 size_t lenlen; 81 82 buf = dest; 83 *buf ++ = 0x30; /* SEQUENCE tag */ 84 lenlen = br_asn1_encode_length(buf, len_seq); 85 buf += lenlen; 86 87 /* version, privateKeyAlgorithm, privateKey tag */ 88 memcpy(buf, PK8_HEAD, sizeof PK8_HEAD); 89 buf += sizeof PK8_HEAD; 90 91 /* privateKey */ 92 buf += br_asn1_encode_length(buf, len_raw); 93 br_encode_rsa_raw_der(buf, sk, pk, d, dlen); 94 95 return 1 + lenlen + len_seq; 96 } 97 } 98