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drafted header encryption
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Logan007
parent
23544640d0
commit
105cc40bd4
104
header_encryption.c
Normal file
104
header_encryption.c
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@ -0,0 +1,104 @@
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#include <stdio.h>
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#include <stdint.h>
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// #include "n2n_wire.h" // n2n_community_t
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#include "n2n.h"
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#include "speck.h"
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#include "portable_endian.h"
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uint32_t decryt_packet_header (uint8_t packet[], uint8_t packet_len,
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char * community_name, speck_ctx * ctx) {
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// assemble IV
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// the last four are ASCII "n2n!" and do not get overwritten
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uint8_t iv[16] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x00, 0x6E, 0x32, 0x6E, 0x21 };
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// the first 96 bits of the packet are used padded with ASCII "n2n!"
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// to full 128 bit IV
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memcopy (iv, packet, 12);
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// alternatively, consider: pearson_hash_128 (iv, packet, 12)
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// try community name as possible key and check for magic bytes
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uint32_t magic = 0x6E326E00; // ="n2n_"
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uint32_t test_magic;
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// check for magic bytes and resonable value in header len field
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speck_he ((uint8_t*)&test_magic, &packet[12], 4, iv, ctx);
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test_magic = be32toh (test_magic);
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if ( ((test_magic << 8) == magic)
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&& ((test_magic >> 24) <= packet_len) // (test_masgic >> 24) is header_len
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) {
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speck_he (&packet[12], &packet[12], (test_magic >> 24) - 12, iv, ctx);
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// restore original packet order
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memcpy (&packet[0], &packet[16], 4);
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memcpy (&packet[4], community_name, N2N_COMMUNITY_SIZE);
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return (1); // successful
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} else
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return (0); // unsuccessful
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}
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int32_t decryt_packet_header_if_required (uint8_t packet[], uint16_t packet_len,
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struct sn_community *communities) {
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if (packet_len < 20)
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return (-1);
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// first, check if header is unenrypted to put it into the fast-lane then
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// the following check is around 99.99962 percent reliable
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// it heavily relies on the structure of packet's common part
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// changes to wire.c:encode/decode_common need to go together with this code
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if ( (packet[19] == (uint8_t)0x00) // null terminated community name
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&& (packet[00] == N2N_PKT_VERSION) // correct packet version
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// && (packet[01] <= N2N_DEFAULT_TTL) // reasonable TTL -- might interfere with hole-punching-related or cli passed higher values ?!
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&& ((be16toh (*(uint16_t*)&(packet[02])) & N2N_FLAGS_TYPE_MASK ) <= MSG_TYPE_MAX_TYPE ) // message type
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&& ( be16toh (*(uint16_t*)&(packet[02])) < N2N_FLAGS_OPTIONS) // flags
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) {
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// most probably unencrypted
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return (1);
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} else {
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// most probably encrypted
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// cycle through the known communities (as keys) to eventually decrypt
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int32_t ret;
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struct sn_community *c, *tmp;
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HASH_ITER (hh, communities, c, tmp) {
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// check if this is an encrypted community
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if ( ret = decrypt_packet_header (packet, packet_len, c->community, c-> ctx) ) {
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// no upgrade from unencrypted to encrypted
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if (c->header_encryption == 1)
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return (-2);
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// set to 'encrypted'
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c->header_encryption = 2;
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// no need to test any further
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return (2);
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}
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}
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// no match
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return (-3);
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}
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}
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int32_t encryt_packet_header (uint8_t packet[], uint8_t header_len, speck_ctx * ctx) {
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if (header_len < 20)
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return (-1);
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memcpy (&packet[16], &packet[00], 4);
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uint8_t iv[16];
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((uint64_t*)iv)[0] = n2n_rand ();
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((uint64_t*)iv)[1] = n2n_rand ();
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const uint32_t magic = 0x006E326E;
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((uint32_t*)iv)[3] = htobe32 (magic);
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iv[12] = header_len;
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speck_he (&packet[12], &packet[12], header_len - 12, iv, ctx);
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}
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123
speck.c
123
speck.c
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@ -1,4 +1,4 @@
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// cipher SPECK -- 128 bit block size -- 256 bit key size
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// cipher SPECK -- 128 bit block size -- 256 bit key size -- CTR mode
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// taken from (and modified: removed pure crypto-stream generation and seperated key expansion)
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// https://github.com/nsacyber/simon-speck-supercop/blob/master/crypto_stream/speck128256ctr/
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@ -565,9 +565,9 @@ int speck_expand_key (const unsigned char *k, speck_context_t *ctx) {
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#else // plain C ----------------------------------------------------------------
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#define ROR64(x,r) (((x)>>(r))|((x)<<(64-(r))))
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#define ROL64(x,r) (((x)<<(r))|((x)>>(64-(r))))
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#define R(x,y,k) (x=ROR64(x,8), x+=y, x^=k, y=ROL64(y,3), y^=x)
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#define ROR(x,r) (((x)>>(r))|((x)<<(64-(r))))
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#define ROL(x,r) (((x)<<(r))|((x)>>(64-(r))))
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#define R(x,y,k) (x=ROR(x,8), x+=y, x^=k, y=ROL(y,3), y^=x)
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static int speck_encrypt (u64 *u, u64 *v, speck_context_t *ctx) {
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@ -642,6 +642,85 @@ int speck_expand_key (const unsigned char *k, speck_context_t *ctx) {
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#endif // AVX, SSE, NEON, plain C ------------------------------------------------
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// cipher SPECK -- 128 bit block size -- 128 bit key size -- CTR mode
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// used for header encryption, thus the prefix 'he_'
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// for now: just plain C -- AVX, SSE, NEON might follow
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#define ROR64(x,r) (((x)>>(r))|((x)<<(64-(r))))
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#define ROL64(x,r) (((x)<<(r))|((x)>>(64-(r))))
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#define R64(x,y,k) (x=ROR64(x,8), x+=y, x^=k, y=ROL64(y,3), y^=x)
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static int speck_encrypt_he (u64 *u, u64 *v, speck_context_t *ctx) {
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u64 i, x=*u, y=*v;
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for (i = 0; i < 32; i++)
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R64 (x, y, ctx->key[i]);
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*u = x; *v = y;
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return 0;
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}
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int speck_he (unsigned char *out, const unsigned char *in, unsigned long long inlen,
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const unsigned char *n, speck_context_t *ctx) {
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u64 i, nonce[2], x, y, t;
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unsigned char *block = malloc(16);
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if (!inlen) {
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free (block);
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return 0;
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}
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nonce[0] = htole64 ( ((u64*)n)[0] );
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nonce[1] = htole64 ( ((u64*)n)[1] );
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t = 0;
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while (inlen >= 16) {
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x = nonce[1]; y = nonce[0]; nonce[0]++;
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speck_encrypt_he (&x, &y, ctx);
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((u64 *)out)[1+t] = htole64 (x ^ ((u64 *)in)[1+t]);
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((u64 *)out)[0+t] = htole64 (y ^ ((u64 *)in)[0+t]);
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t += 2;
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inlen -= 16;
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}
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if (inlen > 0) {
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x = nonce[1]; y = nonce[0];
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speck_encrypt_he (&x, &y, ctx);
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((u64 *)block)[1] = htole64 (x); ((u64 *)block)[0] = htole64 (y);
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for (i = 0; i < inlen; i++)
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out[i+8*t] = block[i] ^ in[i+8*t];
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}
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free(block);
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return 0;
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}
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int speck_expand_key_he (const unsigned char *k, speck_context_t *ctx) {
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u64 A, B;
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u64 i;
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A = htole64 ( ((u64 *)k)[0] );
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B = htole64 ( ((u64 *)k)[1] );
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for (i = 0; i < 32; i ++) {
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ctx->key[i] = A;
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R64 ( B, A, i);
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}
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return 1;
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}
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// code for testing -- to be removed when finished
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/*
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#include <stdio.h> // for testing
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#include <string.h>
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int speck_test () {
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uint8_t key[32] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
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0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
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0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F };
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uint8_t iv[16] = { 0x70, 0x6f, 0x6f, 0x6e, 0x65, 0x72, 0x2e, 0x20,
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0x49, 0x6e, 0x20, 0x74, 0x68, 0x6f, 0x73, 0x65 };
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uint8_t xv[16] = { 0x20, 0x6d, 0x61, 0x64, 0x65, 0x20, 0x69, 0x74,
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0x20, 0x65, 0x71, 0x75, 0x69, 0x76, 0x61, 0x6c };
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uint8_t pt[16] = { 0x00 };
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// expected outcome (according to pp. 35 & 36 of Implementation Guide)
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uint8_t ct[16] = { 0x43, 0x8f, 0x18, 0x9c, 0x8d, 0xb4, 0xee, 0x4e,
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0x3e, 0xf5, 0xc0, 0x05, 0x04, 0x01, 0x09, 0x41 };
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uint8_t xt[16] = { 0x18, 0x0d, 0x57, 0x5c, 0xdf, 0xfe, 0x60, 0x78,
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0x65, 0x32, 0x78, 0x79, 0x51, 0x98, 0x5d, 0xa6 };
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speck_context_t ctx;
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speck_expand_key (key, &ctx);
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@ -667,24 +753,35 @@ int speck_test () {
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#else
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speck_ctr (pt, pt, 16, iv, &ctx);
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#endif
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u64 i;
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// fprintf (stderr, "rk00: %016llx\n", ctx.key[0]);
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// fprintf (stderr, "rk33: %016llx\n", ctx.key[33]);
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// fprintf (stderr, "out : %016lx\n", *(uint64_t*)pt);
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// fprintf (stderr, "mem : " ); for (i=0; i < 16; i++) fprintf (stderr, "%02x ", pt[i]); fprintf (stderr, "\n");
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fprintf (stderr, "rk00: %016llx\n", ctx.key[0]);
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fprintf (stderr, "rk33: %016llx\n", ctx.key[33]);
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fprintf (stderr, "out : %016lx\n", *(uint64_t*)pt);
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fprintf (stderr, "mem : " ); for (i=0; i < 16; i++) fprintf (stderr, "%02x ", pt[i]); fprintf (stderr, "\n");
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int ret = 1;
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for (i=0; i < 16; i++)
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if (pt[i] != ct[i]) ret = 0;
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memset (pt, 0, 16);
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speck_expand_key_he (key, &ctx);
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speck_he (pt, pt, 16, xv, &ctx);
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fprintf (stderr, "rk00: %016llx\n", ctx.key[0]);
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fprintf (stderr, "rk31: %016llx\n", ctx.key[31]);
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fprintf (stderr, "out : %016lx\n", *(uint64_t*)pt);
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fprintf (stderr, "mem : " ); for (i=0; i < 16; i++) fprintf (stderr, "%02x ", pt[i]); fprintf (stderr, "\n");
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for (i=0; i < 16; i++)
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if (pt[i] != xt[i]) ret = 0;
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return (ret);
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}
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/*
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#include <stdio.h> // for testing
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int main (int argc, char* argv[]) {
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int main (int argc, char* argv[]) {
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fprintf (stdout, "SPECK SELF TEST RESULT: %u\n", speck_test (0,NULL));
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}
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}
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*/
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7
speck.h
7
speck.h
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@ -54,3 +54,10 @@ speck_context_t *ctx);
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int speck_expand_key (const unsigned char *k, speck_context_t *ctx);
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int speck_he (unsigned char *out, const unsigned char *in, unsigned long long inlen,
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const unsigned char *n, speck_context_t *ctx);
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int speck_expand_key_he (const unsigned char *k, speck_context_t *ctx);
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