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 inner.h */
 28  const unsigned char *
 29  br_get_curve_OID(int curve)
 30  {
 31  	static const unsigned char OID_secp256r1[] = {
 32  		0x08, 0x2a, 0x86, 0x48, 0xce, 0x3d, 0x03, 0x01, 0x07
 33  	};
 34  	static const unsigned char OID_secp384r1[] = {
 35  		0x05, 0x2b, 0x81, 0x04, 0x00, 0x22
 36  	};
 37  	static const unsigned char OID_secp521r1[] = {
 38  		0x05, 0x2b, 0x81, 0x04, 0x00, 0x23
 39  	};
 40  
 41  	switch (curve) {
 42  	case BR_EC_secp256r1:  return OID_secp256r1;
 43  	case BR_EC_secp384r1:  return OID_secp384r1;
 44  	case BR_EC_secp521r1:  return OID_secp521r1;
 45  	default:
 46  		return NULL;
 47  	}
 48  }
 49  
 50  /* see inner.h */
 51  size_t
 52  br_encode_ec_raw_der_inner(void *dest,
 53  	const br_ec_private_key *sk, const br_ec_public_key *pk,
 54  	int include_curve_oid)
 55  {
 56  	/*
 57  	 * ASN.1 format:
 58  	 *
 59  	 *   ECPrivateKey ::= SEQUENCE {
 60  	 *     version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
 61  	 *     privateKey     OCTET STRING,
 62  	 *     parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
 63  	 *     publicKey  [1] BIT STRING OPTIONAL
 64  	 *   }
 65  	 *
 66  	 * The tages '[0]' and '[1]' are explicit. The 'ECParameters'
 67  	 * is a CHOICE; in our case, it will always be an OBJECT IDENTIFIER
 68  	 * that identifies the curve.
 69  	 *
 70  	 * The value of the 'privateKey' field is the raw unsigned big-endian
 71  	 * encoding of the private key (integer modulo the curve subgroup
 72  	 * order); there is no INTEGER tag, and the leading bit may be 1.
 73  	 * Also, leading bytes of value 0x00 are _not_ removed.
 74  	 *
 75  	 * The 'publicKey' contents are the raw encoded public key point,
 76  	 * normally uncompressed (leading byte of value 0x04, followed
 77  	 * by the unsigned big-endian encodings of the X and Y coordinates,
 78  	 * padded to the full field length if necessary).
 79  	 */
 80  
 81  	size_t len_version, len_privateKey, len_parameters, len_publicKey;
 82  	size_t len_publicKey_bits, len_seq;
 83  	const unsigned char *oid;
 84  
 85  	if (include_curve_oid) {
 86  		oid = br_get_curve_OID(sk->curve);
 87  		if (oid == NULL) {
 88  			return 0;
 89  		}
 90  	} else {
 91  		oid = NULL;
 92  	}
 93  	len_version = 3;
 94  	len_privateKey = 1 + len_of_len(sk->xlen) + sk->xlen;
 95  	if (include_curve_oid) {
 96  		len_parameters = 4 + oid[0];
 97  	} else {
 98  		len_parameters = 0;
 99  	}
100  	if (pk == NULL) {
101  		len_publicKey = 0;
102  		len_publicKey_bits = 0;
103  	} else {
104  		len_publicKey_bits = 2 + len_of_len(pk->qlen) + pk->qlen;
105  		len_publicKey = 1 + len_of_len(len_publicKey_bits)
106  			+ len_publicKey_bits;
107  	}
108  	len_seq = len_version + len_privateKey + len_parameters + len_publicKey;
109  	if (dest == NULL) {
110  		return 1 + len_of_len(len_seq) + len_seq;
111  	} else {
112  		unsigned char *buf;
113  		size_t lenlen;
114  
115  		buf = dest;
116  		*buf ++ = 0x30;  /* SEQUENCE tag */
117  		lenlen = br_asn1_encode_length(buf, len_seq);
118  		buf += lenlen;
119  
120  		/* version */
121  		*buf ++ = 0x02;
122  		*buf ++ = 0x01;
123  		*buf ++ = 0x01;
124  
125  		/* privateKey */
126  		*buf ++ = 0x04;
127  		buf += br_asn1_encode_length(buf, sk->xlen);
128  		memcpy(buf, sk->x, sk->xlen);
129  		buf += sk->xlen;
130  
131  		/* parameters */
132  		if (include_curve_oid) {
133  			*buf ++ = 0xA0;
134  			*buf ++ = oid[0] + 2;
135  			*buf ++ = 0x06;
136  			memcpy(buf, oid, oid[0] + 1);
137  			buf += oid[0] + 1;
138  		}
139  
140  		/* publicKey */
141  		if (pk != NULL) {
142  			*buf ++ = 0xA1;
143  			buf += br_asn1_encode_length(buf, len_publicKey_bits);
144  			*buf ++ = 0x03;
145  			buf += br_asn1_encode_length(buf, pk->qlen + 1);
146  			*buf ++ = 0x00;
147  			memcpy(buf, pk->q, pk->qlen);
148  			/* buf += pk->qlen; */
149  		}
150  
151  		return 1 + lenlen + len_seq;
152  	}
153  }
154  
155  /* see bearssl_x509.h */
156  size_t
157  br_encode_ec_raw_der(void *dest,
158  	const br_ec_private_key *sk, const br_ec_public_key *pk)
159  {
160  	return br_encode_ec_raw_der_inner(dest, sk, pk, 1);
161  }