| yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2015-2018 The OpenSSL Project Authors. All Rights Reserved. |
| 3 | * |
| 4 | * Licensed under the OpenSSL license (the "License"). You may not use |
| 5 | * this file except in compliance with the License. You can obtain a copy |
| 6 | * in the file LICENSE in the source distribution or at |
| 7 | * https://www.openssl.org/source/license.html |
| 8 | */ |
| 9 | |
| 10 | #include <string.h> |
| 11 | #include <openssl/ec.h> |
| 12 | #include <openssl/evp.h> |
| 13 | #include "ec_local.h" |
| 14 | |
| 15 | /* Key derivation function from X9.63/SECG */ |
| 16 | /* Way more than we will ever need */ |
| 17 | #define ECDH_KDF_MAX (1 << 30) |
| 18 | |
| 19 | int ecdh_KDF_X9_63(unsigned char *out, size_t outlen, |
| 20 | const unsigned char *Z, size_t Zlen, |
| 21 | const unsigned char *sinfo, size_t sinfolen, |
| 22 | const EVP_MD *md) |
| 23 | { |
| 24 | EVP_MD_CTX *mctx = NULL; |
| 25 | int rv = 0; |
| 26 | unsigned int i; |
| 27 | size_t mdlen; |
| 28 | unsigned char ctr[4]; |
| 29 | if (sinfolen > ECDH_KDF_MAX || outlen > ECDH_KDF_MAX |
| 30 | || Zlen > ECDH_KDF_MAX) |
| 31 | return 0; |
| 32 | mctx = EVP_MD_CTX_new(); |
| 33 | if (mctx == NULL) |
| 34 | return 0; |
| 35 | mdlen = EVP_MD_size(md); |
| 36 | for (i = 1;; i++) { |
| 37 | unsigned char mtmp[EVP_MAX_MD_SIZE]; |
| 38 | if (!EVP_DigestInit_ex(mctx, md, NULL)) |
| 39 | goto err; |
| 40 | ctr[3] = i & 0xFF; |
| 41 | ctr[2] = (i >> 8) & 0xFF; |
| 42 | ctr[1] = (i >> 16) & 0xFF; |
| 43 | ctr[0] = (i >> 24) & 0xFF; |
| 44 | if (!EVP_DigestUpdate(mctx, Z, Zlen)) |
| 45 | goto err; |
| 46 | if (!EVP_DigestUpdate(mctx, ctr, sizeof(ctr))) |
| 47 | goto err; |
| 48 | if (!EVP_DigestUpdate(mctx, sinfo, sinfolen)) |
| 49 | goto err; |
| 50 | if (outlen >= mdlen) { |
| 51 | if (!EVP_DigestFinal(mctx, out, NULL)) |
| 52 | goto err; |
| 53 | outlen -= mdlen; |
| 54 | if (outlen == 0) |
| 55 | break; |
| 56 | out += mdlen; |
| 57 | } else { |
| 58 | if (!EVP_DigestFinal(mctx, mtmp, NULL)) |
| 59 | goto err; |
| 60 | memcpy(out, mtmp, outlen); |
| 61 | OPENSSL_cleanse(mtmp, mdlen); |
| 62 | break; |
| 63 | } |
| 64 | } |
| 65 | rv = 1; |
| 66 | err: |
| 67 | EVP_MD_CTX_free(mctx); |
| 68 | return rv; |
| 69 | } |
| 70 | |
| 71 | /*- |
| 72 | * The old name for ecdh_KDF_X9_63 |
| 73 | * Retained for ABI compatibility |
| 74 | */ |
| 75 | int ECDH_KDF_X9_62(unsigned char *out, size_t outlen, |
| 76 | const unsigned char *Z, size_t Zlen, |
| 77 | const unsigned char *sinfo, size_t sinfolen, |
| 78 | const EVP_MD *md) |
| 79 | { |
| 80 | return ecdh_KDF_X9_63(out, outlen, Z, Zlen, sinfo, sinfolen, md); |
| 81 | } |