| /* |
| * Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved. |
| * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved |
| * |
| * Licensed under the OpenSSL license (the "License"). You may not use |
| * this file except in compliance with the License. You can obtain a copy |
| * in the file LICENSE in the source distribution or at |
| * https://www.openssl.org/source/license.html |
| */ |
| |
| #include <openssl/err.h> |
| #include <openssl/symhacks.h> |
| |
| #include "ec_lcl.h" |
| |
| int ec_GFp_simple_set_compressed_coordinates(const EC_GROUP *group, |
| EC_POINT *point, |
| const BIGNUM *x_, int y_bit, |
| BN_CTX *ctx) |
| { |
| BN_CTX *new_ctx = NULL; |
| BIGNUM *tmp1, *tmp2, *x, *y; |
| int ret = 0; |
| |
| /* clear error queue */ |
| ERR_clear_error(); |
| |
| if (ctx == NULL) { |
| ctx = new_ctx = BN_CTX_new(); |
| if (ctx == NULL) |
| return 0; |
| } |
| |
| y_bit = (y_bit != 0); |
| |
| BN_CTX_start(ctx); |
| tmp1 = BN_CTX_get(ctx); |
| tmp2 = BN_CTX_get(ctx); |
| x = BN_CTX_get(ctx); |
| y = BN_CTX_get(ctx); |
| if (y == NULL) |
| goto err; |
| |
| /*- |
| * Recover y. We have a Weierstrass equation |
| * y^2 = x^3 + a*x + b, |
| * so y is one of the square roots of x^3 + a*x + b. |
| */ |
| |
| /* tmp1 := x^3 */ |
| if (!BN_nnmod(x, x_, group->field, ctx)) |
| goto err; |
| if (group->meth->field_decode == 0) { |
| /* field_{sqr,mul} work on standard representation */ |
| if (!group->meth->field_sqr(group, tmp2, x_, ctx)) |
| goto err; |
| if (!group->meth->field_mul(group, tmp1, tmp2, x_, ctx)) |
| goto err; |
| } else { |
| if (!BN_mod_sqr(tmp2, x_, group->field, ctx)) |
| goto err; |
| if (!BN_mod_mul(tmp1, tmp2, x_, group->field, ctx)) |
| goto err; |
| } |
| |
| /* tmp1 := tmp1 + a*x */ |
| if (group->a_is_minus3) { |
| if (!BN_mod_lshift1_quick(tmp2, x, group->field)) |
| goto err; |
| if (!BN_mod_add_quick(tmp2, tmp2, x, group->field)) |
| goto err; |
| if (!BN_mod_sub_quick(tmp1, tmp1, tmp2, group->field)) |
| goto err; |
| } else { |
| if (group->meth->field_decode) { |
| if (!group->meth->field_decode(group, tmp2, group->a, ctx)) |
| goto err; |
| if (!BN_mod_mul(tmp2, tmp2, x, group->field, ctx)) |
| goto err; |
| } else { |
| /* field_mul works on standard representation */ |
| if (!group->meth->field_mul(group, tmp2, group->a, x, ctx)) |
| goto err; |
| } |
| |
| if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field)) |
| goto err; |
| } |
| |
| /* tmp1 := tmp1 + b */ |
| if (group->meth->field_decode) { |
| if (!group->meth->field_decode(group, tmp2, group->b, ctx)) |
| goto err; |
| if (!BN_mod_add_quick(tmp1, tmp1, tmp2, group->field)) |
| goto err; |
| } else { |
| if (!BN_mod_add_quick(tmp1, tmp1, group->b, group->field)) |
| goto err; |
| } |
| |
| if (!BN_mod_sqrt(y, tmp1, group->field, ctx)) { |
| unsigned long err = ERR_peek_last_error(); |
| |
| if (ERR_GET_LIB(err) == ERR_LIB_BN |
| && ERR_GET_REASON(err) == BN_R_NOT_A_SQUARE) { |
| ERR_clear_error(); |
| ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, |
| EC_R_INVALID_COMPRESSED_POINT); |
| } else |
| ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, |
| ERR_R_BN_LIB); |
| goto err; |
| } |
| |
| if (y_bit != BN_is_odd(y)) { |
| if (BN_is_zero(y)) { |
| int kron; |
| |
| kron = BN_kronecker(x, group->field, ctx); |
| if (kron == -2) |
| goto err; |
| |
| if (kron == 1) |
| ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, |
| EC_R_INVALID_COMPRESSION_BIT); |
| else |
| /* |
| * BN_mod_sqrt() should have caught this error (not a square) |
| */ |
| ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, |
| EC_R_INVALID_COMPRESSED_POINT); |
| goto err; |
| } |
| if (!BN_usub(y, group->field, y)) |
| goto err; |
| } |
| if (y_bit != BN_is_odd(y)) { |
| ECerr(EC_F_EC_GFP_SIMPLE_SET_COMPRESSED_COORDINATES, |
| ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| |
| if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx)) |
| goto err; |
| |
| ret = 1; |
| |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(new_ctx); |
| return ret; |
| } |
| |
| size_t ec_GFp_simple_point2oct(const EC_GROUP *group, const EC_POINT *point, |
| point_conversion_form_t form, |
| unsigned char *buf, size_t len, BN_CTX *ctx) |
| { |
| size_t ret; |
| BN_CTX *new_ctx = NULL; |
| int used_ctx = 0; |
| BIGNUM *x, *y; |
| size_t field_len, i, skip; |
| |
| if ((form != POINT_CONVERSION_COMPRESSED) |
| && (form != POINT_CONVERSION_UNCOMPRESSED) |
| && (form != POINT_CONVERSION_HYBRID)) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_INVALID_FORM); |
| goto err; |
| } |
| |
| if (EC_POINT_is_at_infinity(group, point)) { |
| /* encodes to a single 0 octet */ |
| if (buf != NULL) { |
| if (len < 1) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL); |
| return 0; |
| } |
| buf[0] = 0; |
| } |
| return 1; |
| } |
| |
| /* ret := required output buffer length */ |
| field_len = BN_num_bytes(group->field); |
| ret = |
| (form == |
| POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len; |
| |
| /* if 'buf' is NULL, just return required length */ |
| if (buf != NULL) { |
| if (len < ret) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, EC_R_BUFFER_TOO_SMALL); |
| goto err; |
| } |
| |
| if (ctx == NULL) { |
| ctx = new_ctx = BN_CTX_new(); |
| if (ctx == NULL) |
| return 0; |
| } |
| |
| BN_CTX_start(ctx); |
| used_ctx = 1; |
| x = BN_CTX_get(ctx); |
| y = BN_CTX_get(ctx); |
| if (y == NULL) |
| goto err; |
| |
| if (!EC_POINT_get_affine_coordinates(group, point, x, y, ctx)) |
| goto err; |
| |
| if ((form == POINT_CONVERSION_COMPRESSED |
| || form == POINT_CONVERSION_HYBRID) && BN_is_odd(y)) |
| buf[0] = form + 1; |
| else |
| buf[0] = form; |
| |
| i = 1; |
| |
| skip = field_len - BN_num_bytes(x); |
| if (skip > field_len) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| while (skip > 0) { |
| buf[i++] = 0; |
| skip--; |
| } |
| skip = BN_bn2bin(x, buf + i); |
| i += skip; |
| if (i != 1 + field_len) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| |
| if (form == POINT_CONVERSION_UNCOMPRESSED |
| || form == POINT_CONVERSION_HYBRID) { |
| skip = field_len - BN_num_bytes(y); |
| if (skip > field_len) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| while (skip > 0) { |
| buf[i++] = 0; |
| skip--; |
| } |
| skip = BN_bn2bin(y, buf + i); |
| i += skip; |
| } |
| |
| if (i != ret) { |
| ECerr(EC_F_EC_GFP_SIMPLE_POINT2OCT, ERR_R_INTERNAL_ERROR); |
| goto err; |
| } |
| } |
| |
| if (used_ctx) |
| BN_CTX_end(ctx); |
| BN_CTX_free(new_ctx); |
| return ret; |
| |
| err: |
| if (used_ctx) |
| BN_CTX_end(ctx); |
| BN_CTX_free(new_ctx); |
| return 0; |
| } |
| |
| int ec_GFp_simple_oct2point(const EC_GROUP *group, EC_POINT *point, |
| const unsigned char *buf, size_t len, BN_CTX *ctx) |
| { |
| point_conversion_form_t form; |
| int y_bit; |
| BN_CTX *new_ctx = NULL; |
| BIGNUM *x, *y; |
| size_t field_len, enc_len; |
| int ret = 0; |
| |
| if (len == 0) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_BUFFER_TOO_SMALL); |
| return 0; |
| } |
| form = buf[0]; |
| y_bit = form & 1; |
| form = form & ~1U; |
| if ((form != 0) && (form != POINT_CONVERSION_COMPRESSED) |
| && (form != POINT_CONVERSION_UNCOMPRESSED) |
| && (form != POINT_CONVERSION_HYBRID)) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| return 0; |
| } |
| if ((form == 0 || form == POINT_CONVERSION_UNCOMPRESSED) && y_bit) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| return 0; |
| } |
| |
| if (form == 0) { |
| if (len != 1) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| return 0; |
| } |
| |
| return EC_POINT_set_to_infinity(group, point); |
| } |
| |
| field_len = BN_num_bytes(group->field); |
| enc_len = |
| (form == |
| POINT_CONVERSION_COMPRESSED) ? 1 + field_len : 1 + 2 * field_len; |
| |
| if (len != enc_len) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| return 0; |
| } |
| |
| if (ctx == NULL) { |
| ctx = new_ctx = BN_CTX_new(); |
| if (ctx == NULL) |
| return 0; |
| } |
| |
| BN_CTX_start(ctx); |
| x = BN_CTX_get(ctx); |
| y = BN_CTX_get(ctx); |
| if (y == NULL) |
| goto err; |
| |
| if (!BN_bin2bn(buf + 1, field_len, x)) |
| goto err; |
| if (BN_ucmp(x, group->field) >= 0) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| goto err; |
| } |
| |
| if (form == POINT_CONVERSION_COMPRESSED) { |
| if (!EC_POINT_set_compressed_coordinates(group, point, x, y_bit, ctx)) |
| goto err; |
| } else { |
| if (!BN_bin2bn(buf + 1 + field_len, field_len, y)) |
| goto err; |
| if (BN_ucmp(y, group->field) >= 0) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| goto err; |
| } |
| if (form == POINT_CONVERSION_HYBRID) { |
| if (y_bit != BN_is_odd(y)) { |
| ECerr(EC_F_EC_GFP_SIMPLE_OCT2POINT, EC_R_INVALID_ENCODING); |
| goto err; |
| } |
| } |
| |
| /* |
| * EC_POINT_set_affine_coordinates is responsible for checking that |
| * the point is on the curve. |
| */ |
| if (!EC_POINT_set_affine_coordinates(group, point, x, y, ctx)) |
| goto err; |
| } |
| |
| ret = 1; |
| |
| err: |
| BN_CTX_end(ctx); |
| BN_CTX_free(new_ctx); |
| return ret; |
| } |
