mirror of https://github.com/ntop/n2n.git
Luca Deri
4 years ago
committed by
GitHub
GitHub
7 changed files with 376 additions and 13 deletions
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/**
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* (C) 2007-20 - ntop.org and contributors |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation; either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not see see <http://www.gnu.org/licenses/>
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* |
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*/ |
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#include "n2n.h" |
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#include "n2n_transforms.h" |
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#ifdef HAVE_OPENSSL_1_1 |
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#include <openssl/sha.h> |
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#include <openssl/evp.h> |
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#include <openssl/err.h> |
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#define N2N_CC20_TRANSFORM_VERSION 1 /* version of the transform encoding */ |
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#define N2N_CC20_IVEC_SIZE 16 |
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#define CC20_KEY_BYTES (256/8) |
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/* ChaCha20 plaintext preamble */ |
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#define TRANSOP_CC20_VER_SIZE 1 /* Support minor variants in encoding in one module. */ |
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#define TRANSOP_CC20_PREAMBLE_SIZE (TRANSOP_CC20_VER_SIZE + N2N_CC20_IVEC_SIZE) |
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typedef unsigned char n2n_cc20_ivec_t[N2N_CC20_IVEC_SIZE]; |
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typedef struct transop_cc20 { |
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EVP_CIPHER_CTX *enc_ctx; /* openssl's reusable evp_* encryption context */ |
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EVP_CIPHER_CTX *dec_ctx; /* openssl's reusable evp_* decryption context */ |
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const EVP_CIPHER *cipher; /* cipher to use: EVP_chacha20() */ |
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uint8_t key[32]; /* the pure key data for payload encryption & decryption */ |
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} transop_cc20_t; |
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/* ****************************************************** */ |
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static int transop_deinit_cc20(n2n_trans_op_t *arg) { |
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transop_cc20_t *priv = (transop_cc20_t *)arg->priv; |
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EVP_CIPHER_CTX_free(priv->enc_ctx); |
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EVP_CIPHER_CTX_free(priv->dec_ctx); |
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if(priv) |
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free(priv); |
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return 0; |
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} |
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/* ****************************************************** */ |
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/* get any erorr message out of openssl
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taken from https://en.wikibooks.org/wiki/OpenSSL/Error_handling */
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static char *openssl_err_as_string (void) { |
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BIO *bio = BIO_new (BIO_s_mem ()); |
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ERR_print_errors (bio); |
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char *buf = NULL; |
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size_t len = BIO_get_mem_data (bio, &buf); |
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char *ret = (char *) calloc (1, 1 + len); |
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if(ret) |
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memcpy (ret, buf, len); |
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BIO_free (bio); |
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return ret; |
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} |
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/* ****************************************************** */ |
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static void set_cc20_iv(transop_cc20_t *priv, n2n_cc20_ivec_t ivec) { |
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// keep in mind the following condition: N2N_CC20_IVEC_SIZE % sizeof(rand_value) == 0 !
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uint32_t rand_value; |
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for (uint8_t i = 0; i < N2N_CC20_IVEC_SIZE; i += sizeof(rand_value)) { |
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rand_value = rand(); // CONCERN: rand() is not consideren cryptographicly secure, REPLACE later
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memcpy(ivec + i, &rand_value, sizeof(rand_value)); |
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} |
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} |
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/* ****************************************************** */ |
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/** The ChaCha20 packet format consists of:
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* |
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* - a 8-bit cc20 encoding version in clear text |
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* - a 128-bit random IV |
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* - encrypted payload. |
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* |
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* [V|IIII|DDDDDDDDDDDDDDDDDDDDD] |
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* |<---- encrypted ---->| |
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*/ |
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static int transop_encode_cc20(n2n_trans_op_t * arg, |
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uint8_t * outbuf, |
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size_t out_len, |
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const uint8_t * inbuf, |
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size_t in_len, |
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const uint8_t * peer_mac) { |
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int len=-1; |
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transop_cc20_t * priv = (transop_cc20_t *)arg->priv; |
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uint8_t assembly[N2N_PKT_BUF_SIZE] = {0}; |
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if(in_len <= N2N_PKT_BUF_SIZE) { |
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if((in_len + TRANSOP_CC20_PREAMBLE_SIZE) <= out_len) { |
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size_t idx=0; |
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n2n_cc20_ivec_t enc_ivec = {0}; |
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traceEvent(TRACE_DEBUG, "encode_cc20 %lu bytes", in_len); |
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/* Encode the ChaCha20 format version. */ |
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encode_uint8(outbuf, &idx, N2N_CC20_TRANSFORM_VERSION); |
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/* Generate and encode the IV. */ |
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set_cc20_iv(priv, enc_ivec); |
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encode_buf(outbuf, &idx, &enc_ivec, N2N_CC20_IVEC_SIZE); |
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traceEvent(TRACE_DEBUG, "encode_cc20 iv=%016llx:%016llx", |
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htobe64(*(uint64_t*)&enc_ivec[0]), |
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htobe64(*(uint64_t*)&enc_ivec[8]) ); |
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/* Encrypt the assembly contents and write the ciphertext after the iv. */ |
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/* len is set to the length of the cipher plain text to be encrpyted
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which is (in this case) identical to original packet lentgh */ |
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len = in_len; |
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/* The assembly buffer is a source for encrypting data.
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* The whole contents of assembly are encrypted. */ |
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memcpy(assembly, inbuf, in_len); |
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EVP_CIPHER_CTX *ctx = priv->enc_ctx; |
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int evp_len; |
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int evp_ciphertext_len; |
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if(1 == EVP_EncryptInit_ex(ctx, priv->cipher, NULL, priv->key, enc_ivec)) { |
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if(1 == EVP_CIPHER_CTX_set_padding(ctx, 0)) { |
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if(1 == EVP_EncryptUpdate(ctx, outbuf + TRANSOP_CC20_PREAMBLE_SIZE, &evp_len, assembly, len)) { |
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evp_ciphertext_len = evp_len; |
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if(1 == EVP_EncryptFinal_ex(ctx, outbuf + TRANSOP_CC20_PREAMBLE_SIZE + evp_len, &evp_len)) { |
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evp_ciphertext_len += evp_len; |
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if(evp_ciphertext_len != len) |
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traceEvent(TRACE_ERROR, "encode_cc20 openssl encryption: encrypted %u bytes where %u were expected.\n", |
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evp_ciphertext_len, len); |
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} else |
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traceEvent(TRACE_ERROR, "encode_cc20 openssl final encryption: %s\n", openssl_err_as_string()); |
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} else |
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traceEvent(TRACE_ERROR, "encode_cc20 openssl encrpytion: %s\n", openssl_err_as_string()); |
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} else |
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traceEvent(TRACE_ERROR, "encode_cc20 openssl padding setup: %s\n", openssl_err_as_string()); |
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} else |
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traceEvent(TRACE_ERROR, "encode_cc20 openssl init: %s\n", openssl_err_as_string()); |
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EVP_CIPHER_CTX_reset(ctx); |
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len += TRANSOP_CC20_PREAMBLE_SIZE; /* size of data carried in UDP. */ |
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} else |
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traceEvent(TRACE_ERROR, "encode_cc20 outbuf too small."); |
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} else |
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traceEvent(TRACE_ERROR, "encode_cc20 inbuf too big to encrypt."); |
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return len; |
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} |
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/* ****************************************************** */ |
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/* See transop_encode_cc20 for packet format */ |
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static int transop_decode_cc20(n2n_trans_op_t * arg, |
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uint8_t * outbuf, |
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size_t out_len, |
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const uint8_t * inbuf, |
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size_t in_len, |
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const uint8_t * peer_mac) { |
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int len=0; |
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transop_cc20_t * priv = (transop_cc20_t *)arg->priv; |
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uint8_t assembly[N2N_PKT_BUF_SIZE]; |
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if(((in_len - TRANSOP_CC20_PREAMBLE_SIZE) <= N2N_PKT_BUF_SIZE) /* Cipher text fits in assembly */ |
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&& (in_len >= TRANSOP_CC20_PREAMBLE_SIZE) /* Has at least version, iv */ |
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) |
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{ |
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size_t rem=in_len; |
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size_t idx=0; |
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uint8_t cc20_enc_ver=0; |
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n2n_cc20_ivec_t dec_ivec = {0}; |
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/* Get the encoding version to make sure it is supported */ |
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decode_uint8(&cc20_enc_ver, inbuf, &rem, &idx ); |
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if(N2N_CC20_TRANSFORM_VERSION == cc20_enc_ver) { |
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traceEvent(TRACE_DEBUG, "decode_cc20 %lu bytes", in_len); |
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len = (in_len - TRANSOP_CC20_PREAMBLE_SIZE); |
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/* Get the IV */ |
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decode_buf((uint8_t *)&dec_ivec, N2N_CC20_IVEC_SIZE, inbuf, &rem, &idx); |
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traceEvent(TRACE_DEBUG, "decode_cc20 iv=%016llx:%016llx", |
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htobe64(*(uint64_t*)&dec_ivec[0]), |
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htobe64(*(uint64_t*)&dec_ivec[8]) ); |
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EVP_CIPHER_CTX *ctx = priv->dec_ctx; |
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int evp_len; |
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int evp_plaintext_len; |
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if(1 == EVP_DecryptInit_ex(ctx, priv->cipher, NULL, priv->key, dec_ivec)) { |
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if(1 == EVP_CIPHER_CTX_set_padding(ctx, 0)) { |
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if(1 == EVP_DecryptUpdate(ctx, assembly, &evp_len, inbuf + TRANSOP_CC20_PREAMBLE_SIZE, len)) { |
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evp_plaintext_len = evp_len; |
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if(1 == EVP_DecryptFinal_ex(ctx, assembly + evp_len, &evp_len)) { |
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evp_plaintext_len += evp_len; |
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if(evp_plaintext_len != len) |
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traceEvent(TRACE_ERROR, "decode_cc20 openssl decryption: decrypted %u bytes where %u were expected.\n", |
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evp_plaintext_len, len); |
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} else |
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traceEvent(TRACE_ERROR, "decode_cc20 openssl final decryption: %s\n", openssl_err_as_string()); |
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} else |
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traceEvent(TRACE_ERROR, "decode_cc20 openssl decrpytion: %s\n", openssl_err_as_string()); |
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} else |
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traceEvent(TRACE_ERROR, "decode_cc20 openssl padding setup: %s\n", openssl_err_as_string()); |
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} else |
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traceEvent(TRACE_ERROR, "decode_cc20 openssl init: %s\n", openssl_err_as_string()); |
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EVP_CIPHER_CTX_reset(ctx); |
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memcpy(outbuf, assembly, len); |
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} else |
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traceEvent(TRACE_ERROR, "decode_cc20 unsupported ChaCha20 version %u.", cc20_enc_ver); |
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} else |
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traceEvent(TRACE_ERROR, "decode_cc20 inbuf wrong size (%ul) to decrypt.", in_len); |
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return len; |
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} |
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/* ****************************************************** */ |
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static int setup_cc20_key(transop_cc20_t *priv, const uint8_t *key, ssize_t key_size) { |
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uint8_t key_mat_buf[SHA256_DIGEST_LENGTH]; |
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priv->cipher = EVP_chacha20(); |
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/* Clear out any old possibly longer key matter. */ |
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memset(&(priv->key), 0, sizeof(priv->key) ); |
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/* The input key always gets hashed to make a more unpredictable and more complete use of the key space */ |
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SHA256(key, key_size, key_mat_buf); |
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memcpy (priv->key, key_mat_buf, SHA256_DIGEST_LENGTH); |
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traceEvent(TRACE_DEBUG, "ChaCha20 key setup completed\n"); |
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return(0); |
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} |
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/* ****************************************************** */ |
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static void transop_tick_cc20(n2n_trans_op_t * arg, time_t now) { ; } |
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/* ****************************************************** */ |
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/* ChaCha20 initialization function */ |
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int n2n_transop_cc20_init(const n2n_edge_conf_t *conf, n2n_trans_op_t *ttt) { |
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transop_cc20_t *priv; |
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const u_char *encrypt_key = (const u_char *)conf->encrypt_key; |
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size_t encrypt_key_len = strlen(conf->encrypt_key); |
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memset(ttt, 0, sizeof(*ttt)); |
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ttt->transform_id = N2N_TRANSFORM_ID_CHACHA20; |
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ttt->tick = transop_tick_cc20; |
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ttt->deinit = transop_deinit_cc20; |
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ttt->fwd = transop_encode_cc20; |
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ttt->rev = transop_decode_cc20; |
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priv = (transop_cc20_t*) calloc(1, sizeof(transop_cc20_t)); |
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if(!priv) { |
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traceEvent(TRACE_ERROR, "cannot allocate transop_cc20_t memory"); |
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return(-1); |
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} |
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ttt->priv = priv; |
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/* Setup openssl's reusable evp_* contexts for encryption and decryption*/ |
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if(!(priv->enc_ctx = EVP_CIPHER_CTX_new())) { |
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traceEvent(TRACE_ERROR, "openssl's evp_* encryption context creation: %s\n", openssl_err_as_string()); |
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return(-1); |
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} |
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if(!(priv->dec_ctx = EVP_CIPHER_CTX_new())) { |
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traceEvent(TRACE_ERROR, "openssl's evp_* decryption context creation: %s\n", openssl_err_as_string()); |
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return(-1); |
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} |
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/* Setup the cipher and key */ |
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return(setup_cc20_key(priv, encrypt_key, encrypt_key_len)); |
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} |
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#endif /* HAVE_OPENSSL_1_1 */ |
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