1 /* Copyright (c) 2015, Google Inc. 2 * 3 * Permission to use, copy, modify, and/or distribute this software for any 4 * purpose with or without fee is hereby granted, provided that the above 5 * copyright notice and this permission notice appear in all copies. 6 * 7 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 8 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 9 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 10 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 11 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION 12 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN 13 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ 14 15 #include <openssl/bn.h> 16 17 #include <openssl/bytestring.h> 18 #include <openssl/err.h> 19 20 21 int BN_parse_asn1_unsigned(CBS *cbs, BIGNUM *ret) { 22 CBS child; 23 if (!CBS_get_asn1(cbs, &child, CBS_ASN1_INTEGER) || 24 CBS_len(&child) == 0) { 25 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING); 26 return 0; 27 } 28 29 if (CBS_data(&child)[0] & 0x80) { 30 OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER); 31 return 0; 32 } 33 34 // INTEGERs must be minimal. 35 if (CBS_data(&child)[0] == 0x00 && 36 CBS_len(&child) > 1 && 37 !(CBS_data(&child)[1] & 0x80)) { 38 OPENSSL_PUT_ERROR(BN, BN_R_BAD_ENCODING); 39 return 0; 40 } 41 42 return BN_bin2bn(CBS_data(&child), CBS_len(&child), ret) != NULL; 43 } 44 45 int BN_marshal_asn1(CBB *cbb, const BIGNUM *bn) { 46 // Negative numbers are unsupported. 47 if (BN_is_negative(bn)) { 48 OPENSSL_PUT_ERROR(BN, BN_R_NEGATIVE_NUMBER); 49 return 0; 50 } 51 52 CBB child; 53 if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER) || 54 // The number must be padded with a leading zero if the high bit would 55 // otherwise be set or if |bn| is zero. 56 (BN_num_bits(bn) % 8 == 0 && !CBB_add_u8(&child, 0x00)) || 57 !BN_bn2cbb_padded(&child, BN_num_bytes(bn), bn) || 58 !CBB_flush(cbb)) { 59 OPENSSL_PUT_ERROR(BN, BN_R_ENCODE_ERROR); 60 return 0; 61 } 62 63 return 1; 64 } 65
