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/*
* 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_rsa_pkcs8_der(void *dest, const br_rsa_private_key *sk,
const br_rsa_public_key *pk, const void *d, size_t dlen)
{
/*
* 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 '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
* rsaEncryption, with NULL parameters. The 'privateKey' is an
* OCTET STRING, whose value is the "raw DER" encoding of the
* key pair.
*
* Since the private key value comes last, this function really
* adds a header, which is mostly fixed (only some lengths have
* to be modified.
*/
/*
* Concatenation of:
* - DER encoding of an INTEGER of value 0 (the 'version' field)
* - DER encoding of a PrivateKeyAlgorithmIdentifier that uses
* the rsaEncryption OID, and NULL parameters
* - An OCTET STRING tag
*/
static const unsigned char PK8_HEAD[] = {
0x02, 0x01, 0x00,
0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00,
0x04
};
size_t len_raw, len_seq;
len_raw = br_encode_rsa_raw_der(NULL, sk, pk, d, dlen);
len_seq = (sizeof PK8_HEAD) + len_of_len(len_raw) + len_raw;
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, privateKeyAlgorithm, privateKey tag */
memcpy(buf, PK8_HEAD, sizeof PK8_HEAD);
buf += sizeof PK8_HEAD;
/* privateKey */
buf += br_asn1_encode_length(buf, len_raw);
br_encode_rsa_raw_der(buf, sk, pk, d, dlen);
return 1 + lenlen + len_seq;
}
}
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