b9c579db6d
RSA and ECDSA will both require being able to convert ASN.1 INTEGERs to and from DER. Don't bother handling negative BIGNUMs for now. It doesn't seem necessary and saves bothering with two's-complement vs sign-and-magnitude. BUG=499653 Change-Id: I1e80052067ed528809493af73b04f82539d564ff Reviewed-on: https://boringssl-review.googlesource.com/5268 Reviewed-by: Adam Langley <agl@google.com>
75 lines
2.3 KiB
C
75 lines
2.3 KiB
C
/* Copyright (c) 2015, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#include <openssl/bn.h>
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#include <openssl/bytestring.h>
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#include <openssl/err.h>
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int BN_cbs2unsigned(CBS *cbs, BIGNUM *ret) {
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CBS child;
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if (!CBS_get_asn1(cbs, &child, CBS_ASN1_INTEGER) ||
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CBS_len(&child) == 0) {
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OPENSSL_PUT_ERROR(BN, BN_cbs2unsigned, BN_R_BAD_ENCODING);
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return 0;
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}
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if (CBS_data(&child)[0] & 0x80) {
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OPENSSL_PUT_ERROR(BN, BN_cbs2unsigned, BN_R_NEGATIVE_NUMBER);
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return 0;
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}
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/* INTEGERs must be minimal. */
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if (CBS_data(&child)[0] == 0x00 &&
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CBS_len(&child) > 1 &&
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!(CBS_data(&child)[1] & 0x80)) {
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OPENSSL_PUT_ERROR(BN, BN_cbs2unsigned, BN_R_BAD_ENCODING);
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return 0;
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}
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return BN_bin2bn(CBS_data(&child), CBS_len(&child), ret) != NULL;
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}
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int BN_bn2cbb(CBB *cbb, const BIGNUM *bn) {
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/* Negative numbers are unsupported. */
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if (BN_is_negative(bn)) {
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OPENSSL_PUT_ERROR(BN, BN_bn2cbb, BN_R_NEGATIVE_NUMBER);
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return 0;
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}
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CBB child;
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if (!CBB_add_asn1(cbb, &child, CBS_ASN1_INTEGER)) {
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OPENSSL_PUT_ERROR(BN, BN_bn2cbb, BN_R_ENCODE_ERROR);
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return 0;
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}
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/* The number must be padded with a leading zero if the high bit would
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* otherwise be set (or |bn| is zero). */
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if (BN_num_bits(bn) % 8 == 0 &&
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!CBB_add_u8(&child, 0x00)) {
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OPENSSL_PUT_ERROR(BN, BN_bn2cbb, BN_R_ENCODE_ERROR);
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return 0;
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}
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uint8_t *out;
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if (!CBB_add_space(&child, &out, BN_num_bytes(bn))) {
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OPENSSL_PUT_ERROR(BN, BN_bn2cbb, BN_R_ENCODE_ERROR);
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return 0;
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}
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BN_bn2bin(bn, out);
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if (!CBB_flush(cbb)) {
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OPENSSL_PUT_ERROR(BN, BN_bn2cbb, BN_R_ENCODE_ERROR);
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return 0;
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}
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return 1;
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}
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