/* * Copyright (C) 2017 Denys Vlasenko * * Licensed under GPLv2, see file LICENSE in this source tree. */ //config:config TLS //config: bool "tls (debugging)" //config: default n //applet:IF_TLS(APPLET(tls, BB_DIR_USR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_TLS) += tls.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm_montgomery_reduce.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm_mul_comba.o //kbuild:lib-$(CONFIG_TLS) += tls_pstm_sqr_comba.o //kbuild:lib-$(CONFIG_TLS) += tls_rsa.o //kbuild:lib-$(CONFIG_TLS) += tls_aes.o ////kbuild:lib-$(CONFIG_TLS) += tls_aes_gcm.o //usage:#define tls_trivial_usage //usage: "HOST[:PORT]" //usage:#define tls_full_usage "\n\n" #include "tls.h" #define TLS_DEBUG 1 #define TLS_DEBUG_HASH 0 #define TLS_DEBUG_DER 0 #if TLS_DEBUG # define dbg(...) fprintf(stderr, __VA_ARGS__) #else # define dbg(...) ((void)0) #endif #if TLS_DEBUG_DER # define dbg_der(...) fprintf(stderr, __VA_ARGS__) #else # define dbg_der(...) ((void)0) #endif #define RECORD_TYPE_CHANGE_CIPHER_SPEC 20 #define RECORD_TYPE_ALERT 21 #define RECORD_TYPE_HANDSHAKE 22 #define RECORD_TYPE_APPLICATION_DATA 23 #define HANDSHAKE_HELLO_REQUEST 0 #define HANDSHAKE_CLIENT_HELLO 1 #define HANDSHAKE_SERVER_HELLO 2 #define HANDSHAKE_HELLO_VERIFY_REQUEST 3 #define HANDSHAKE_NEW_SESSION_TICKET 4 #define HANDSHAKE_CERTIFICATE 11 #define HANDSHAKE_SERVER_KEY_EXCHANGE 12 #define HANDSHAKE_CERTIFICATE_REQUEST 13 #define HANDSHAKE_SERVER_HELLO_DONE 14 #define HANDSHAKE_CERTIFICATE_VERIFY 15 #define HANDSHAKE_CLIENT_KEY_EXCHANGE 16 #define HANDSHAKE_FINISHED 20 #define SSL_HS_RANDOM_SIZE 32 #define SSL_HS_RSA_PREMASTER_SIZE 48 #define SSL_NULL_WITH_NULL_NULL 0x0000 #define SSL_RSA_WITH_NULL_MD5 0x0001 #define SSL_RSA_WITH_NULL_SHA 0x0002 #define SSL_RSA_WITH_RC4_128_MD5 0x0004 #define SSL_RSA_WITH_RC4_128_SHA 0x0005 #define SSL_RSA_WITH_3DES_EDE_CBC_SHA 0x000A /* 10 */ #define TLS_RSA_WITH_AES_128_CBC_SHA 0x002F /* 47 */ #define TLS_RSA_WITH_AES_256_CBC_SHA 0x0035 /* 53 */ #define TLS_RSA_WITH_NULL_SHA256 0x003B /* 59 */ #define TLS_EMPTY_RENEGOTIATION_INFO_SCSV 0x00FF #define TLS_RSA_WITH_IDEA_CBC_SHA 0x0007 /* 7 */ #define SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA 0x0016 /* 22 */ #define SSL_DH_anon_WITH_RC4_128_MD5 0x0018 /* 24 */ #define SSL_DH_anon_WITH_3DES_EDE_CBC_SHA 0x001B /* 27 */ #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA 0x0033 /* 51 */ #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA 0x0039 /* 57 */ #define TLS_DHE_RSA_WITH_AES_128_CBC_SHA256 0x0067 /* 103 */ #define TLS_DHE_RSA_WITH_AES_256_CBC_SHA256 0x006B /* 107 */ #define TLS_DH_anon_WITH_AES_128_CBC_SHA 0x0034 /* 52 */ #define TLS_DH_anon_WITH_AES_256_CBC_SHA 0x003A /* 58 */ #define TLS_RSA_WITH_AES_128_CBC_SHA256 0x003C /* 60 */ #define TLS_RSA_WITH_AES_256_CBC_SHA256 0x003D /* 61 */ #define TLS_RSA_WITH_SEED_CBC_SHA 0x0096 /* 150 */ #define TLS_PSK_WITH_AES_128_CBC_SHA 0x008C /* 140 */ #define TLS_PSK_WITH_AES_128_CBC_SHA256 0x00AE /* 174 */ #define TLS_PSK_WITH_AES_256_CBC_SHA384 0x00AF /* 175 */ #define TLS_PSK_WITH_AES_256_CBC_SHA 0x008D /* 141 */ #define TLS_DHE_PSK_WITH_AES_128_CBC_SHA 0x0090 /* 144 */ #define TLS_DHE_PSK_WITH_AES_256_CBC_SHA 0x0091 /* 145 */ #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA 0xC004 /* 49156 */ #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA 0xC005 /* 49157 */ #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA 0xC009 /* 49161 */ #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA 0xC00A /* 49162 */ #define TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA 0xC012 /* 49170 */ #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA 0xC013 /* 49171 */ #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA 0xC014 /* 49172 */ #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA 0xC00E /* 49166 */ #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA 0xC00F /* 49167 */ #define TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 0xC023 /* 49187 */ #define TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 0xC024 /* 49188 */ #define TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA256 0xC025 /* 49189 */ #define TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA384 0xC026 /* 49190 */ #define TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 0xC027 /* 49191 */ #define TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 0xC028 /* 49192 */ #define TLS_ECDH_RSA_WITH_AES_128_CBC_SHA256 0xC029 /* 49193 */ #define TLS_ECDH_RSA_WITH_AES_256_CBC_SHA384 0xC02A /* 49194 */ // RFC 5288 "AES Galois Counter Mode (GCM) Cipher Suites for TLS" #define TLS_RSA_WITH_AES_128_GCM_SHA256 0x009C /* 156 */ #define TLS_RSA_WITH_AES_256_GCM_SHA384 0x009D /* 157 */ #define TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 0xC02B /* 49195 */ #define TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 0xC02C /* 49196 */ #define TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 0xC02D /* 49197 */ #define TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 0xC02E /* 49198 */ #define TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 0xC02F /* 49199 */ #define TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 0xC030 /* 49200 */ #define TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 0xC031 /* 49201 */ #define TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 0xC032 /* 49202 */ //Tested against kernel.org: //TLS 1.1 //#define TLS_MAJ 3 //#define TLS_MIN 2 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE //TLS 1.2 #define TLS_MAJ 3 #define TLS_MIN 3 //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA // ok, recvs SERVER_KEY_EXCHANGE *** matrixssl uses this on my box //#define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE // All GCMs: //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 // ok, recvs SERVER_KEY_EXCHANGE //#define CIPHER_ID TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_256_GCM_SHA384 //#define CIPHER_ID TLS_ECDH_ECDSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_256_GCM_SHA384 //#define CIPHER_ID TLS_ECDH_RSA_WITH_AES_128_GCM_SHA256 // SSL_ALERT_HANDSHAKE_FAILURE //#define CIPHER_ID TLS_RSA_WITH_AES_256_GCM_SHA384 // ok, no SERVER_KEY_EXCHANGE //#define CIPHER_ID TLS_RSA_WITH_AES_128_GCM_SHA256 // ok, no SERVER_KEY_EXCHANGE *** select this? //#define CIPHER_ID TLS_DH_anon_WITH_AES_256_CBC_SHA // SSL_ALERT_HANDSHAKE_FAILURE //^^^^^^^^^^^^^^^^^^^^^^^ (tested b/c this one doesn't req server certs... no luck) //test TLS_RSA_WITH_AES_128_CBC_SHA, in TLS 1.2 it's mandated to be always supported // works against "openssl s_server -cipher NULL" // and against wolfssl-3.9.10-stable/examples/server/server.c: //#define CIPHER_ID TLS_RSA_WITH_NULL_SHA256 // for testing (does everything except encrypting) // "works", meaning // "can send encrypted FINISHED to wolfssl-3.9.10-stable/examples/server/server.c", // don't yet read its encrypted answers: #define CIPHER_ID TLS_RSA_WITH_AES_256_CBC_SHA256 // ok, no SERVER_KEY_EXCHANGE enum { SHA256_INSIZE = 64, SHA256_OUTSIZE = 32, AES_BLOCKSIZE = 16, AES128_KEYSIZE = 16, AES256_KEYSIZE = 32, }; struct record_hdr { uint8_t type; uint8_t proto_maj, proto_min; uint8_t len16_hi, len16_lo; }; typedef struct tls_state { int fd; psRsaKey_t server_rsa_pub_key; sha256_ctx_t handshake_sha256_ctx; uint8_t client_and_server_rand32[2 * 32]; uint8_t master_secret[48]; uint8_t encrypt_on_write; int min_encrypted_len_on_read; uint8_t client_write_MAC_key[SHA256_OUTSIZE]; uint8_t server_write_MAC_key[SHA256_OUTSIZE]; uint8_t client_write_key[AES256_KEYSIZE]; uint8_t server_write_key[AES256_KEYSIZE]; // RFC 5246 // sequence number // Each connection state contains a sequence number, which is // maintained separately for read and write states. The sequence // number MUST be set to zero whenever a connection state is made the // active state. Sequence numbers are of type uint64 and may not // exceed 2^64-1. uint64_t write_seq64_be; // RFC 5246 // |6.2.1. Fragmentation // | The record layer fragments information blocks into TLSPlaintext // | records carrying data in chunks of 2^14 bytes or less. Client // | message boundaries are not preserved in the record layer (i.e., // | multiple client messages of the same ContentType MAY be coalesced // | into a single TLSPlaintext record, or a single message MAY be // | fragmented across several records) // |... // | length // | The length (in bytes) of the following TLSPlaintext.fragment. // | The length MUST NOT exceed 2^14. // |... // | 6.2.2. Record Compression and Decompression // |... // | Compression must be lossless and may not increase the content length // | by more than 1024 bytes. If the decompression function encounters a // | TLSCompressed.fragment that would decompress to a length in excess of // | 2^14 bytes, it MUST report a fatal decompression failure error. // |... // | length // | The length (in bytes) of the following TLSCompressed.fragment. // | The length MUST NOT exceed 2^14 + 1024. // // Since our buffer also contains 5-byte headers, make it a bit bigger: int insize; int tail; //needed? uint64_t align____; uint8_t inbuf[20*1024]; uint8_t outbuf[20*1024]; } tls_state_t; static unsigned get24be(const uint8_t *p) { return 0x100*(0x100*p[0] + p[1]) + p[2]; } #if TLS_DEBUG static void dump_hex(const char *fmt, const void *vp, int len) { char hexbuf[32 * 1024 + 4]; const uint8_t *p = vp; bin2hex(hexbuf, (void*)p, len)[0] = '\0'; dbg(fmt, hexbuf); } static void dump_tls_record(const void *vp, int len) { const uint8_t *p = vp; while (len > 0) { unsigned xhdr_len; if (len < 5) { dump_hex("< |%s|\n", p, len); return; } xhdr_len = 0x100*p[3] + p[4]; dbg("< hdr_type:%u ver:%u.%u len:%u", p[0], p[1], p[2], xhdr_len); p += 5; len -= 5; if (len >= 4 && p[-5] == RECORD_TYPE_HANDSHAKE) { unsigned len24 = get24be(p + 1); dbg(" type:%u len24:%u", p[0], len24); } if (xhdr_len > len) xhdr_len = len; dump_hex(" |%s|\n", p, xhdr_len); p += xhdr_len; len -= xhdr_len; } } #endif void tls_get_random(void *buf, unsigned len) { if (len != open_read_close("/dev/urandom", buf, len)) xfunc_die(); } //TODO rename this to sha256_hash, and sha256_hash -> sha256_update static void hash_sha256(uint8_t out[SHA256_OUTSIZE], const void *data, unsigned size) { sha256_ctx_t ctx; sha256_begin(&ctx); sha256_hash(&ctx, data, size); sha256_end(&ctx, out); } /* Nondestructively see the current hash value */ static void sha256_peek(sha256_ctx_t *ctx, void *buffer) { sha256_ctx_t ctx_copy = *ctx; sha256_end(&ctx_copy, buffer); } #if TLS_DEBUG_HASH static void sha256_hash_dbg(const char *fmt, sha256_ctx_t *ctx, const void *buffer, size_t len) { uint8_t h[SHA256_OUTSIZE]; sha256_hash(ctx, buffer, len); dump_hex(fmt, buffer, len); dbg(" (%u) ", (int)len); sha256_peek(ctx, h); dump_hex("%s\n", h, SHA256_OUTSIZE); } #else # define sha256_hash_dbg(fmt, ctx, buffer, len) \ sha256_hash(ctx, buffer, len) #endif // RFC 2104 // HMAC(key, text) based on a hash H (say, sha256) is: // ipad = [0x36 x INSIZE] // opad = [0x5c x INSIZE] // HMAC(key, text) = H((key XOR opad) + H((key XOR ipad) + text)) // // H(key XOR opad) and H(key XOR ipad) can be precomputed // if we often need HMAC hmac with the same key. // // text is often given in disjoint pieces. static void hmac_sha256_precomputed_v(uint8_t out[SHA256_OUTSIZE], sha256_ctx_t *hashed_key_xor_ipad, sha256_ctx_t *hashed_key_xor_opad, va_list va) { uint8_t *text; /* hashed_key_xor_ipad contains unclosed "H((key XOR ipad) +" state */ /* hashed_key_xor_opad contains unclosed "H((key XOR opad) +" state */ /* calculate out = H((key XOR ipad) + text) */ while ((text = va_arg(va, uint8_t*)) != NULL) { unsigned text_size = va_arg(va, unsigned); sha256_hash(hashed_key_xor_ipad, text, text_size); } sha256_end(hashed_key_xor_ipad, out); /* out = H((key XOR opad) + out) */ sha256_hash(hashed_key_xor_opad, out, SHA256_OUTSIZE); sha256_end(hashed_key_xor_opad, out); } static void hmac_sha256(uint8_t out[SHA256_OUTSIZE], uint8_t *key, unsigned key_size, ...) { sha256_ctx_t hashed_key_xor_ipad; sha256_ctx_t hashed_key_xor_opad; uint8_t key_xor_ipad[SHA256_INSIZE]; uint8_t key_xor_opad[SHA256_INSIZE]; uint8_t tempkey[SHA256_OUTSIZE]; va_list va; int i; va_start(va, key_size); // "The authentication key can be of any length up to INSIZE, the // block length of the hash function. Applications that use keys longer // than INSIZE bytes will first hash the key using H and then use the // resultant OUTSIZE byte string as the actual key to HMAC." if (key_size > SHA256_INSIZE) { hash_sha256(tempkey, key, key_size); key = tempkey; key_size = SHA256_OUTSIZE; } for (i = 0; i < key_size; i++) { key_xor_ipad[i] = key[i] ^ 0x36; key_xor_opad[i] = key[i] ^ 0x5c; } for (; i < SHA256_INSIZE; i++) { key_xor_ipad[i] = 0x36; key_xor_opad[i] = 0x5c; } sha256_begin(&hashed_key_xor_ipad); sha256_hash(&hashed_key_xor_ipad, key_xor_ipad, SHA256_INSIZE); sha256_begin(&hashed_key_xor_opad); sha256_hash(&hashed_key_xor_opad, key_xor_opad, SHA256_INSIZE); hmac_sha256_precomputed_v(out, &hashed_key_xor_ipad, &hashed_key_xor_opad, va); va_end(va); } // RFC 5246: // 5. HMAC and the Pseudorandom Function //... // In this section, we define one PRF, based on HMAC. This PRF with the // SHA-256 hash function is used for all cipher suites defined in this // document and in TLS documents published prior to this document when // TLS 1.2 is negotiated. //... // P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) + // HMAC_hash(secret, A(2) + seed) + // HMAC_hash(secret, A(3) + seed) + ... // where + indicates concatenation. // A() is defined as: // A(0) = seed // A(1) = HMAC_hash(secret, A(0)) = HMAC_hash(secret, seed) // A(i) = HMAC_hash(secret, A(i-1)) // P_hash can be iterated as many times as necessary to produce the // required quantity of data. For example, if P_SHA256 is being used to // create 80 bytes of data, it will have to be iterated three times // (through A(3)), creating 96 bytes of output data; the last 16 bytes // of the final iteration will then be discarded, leaving 80 bytes of // output data. // // TLS's PRF is created by applying P_hash to the secret as: // // PRF(secret, label, seed) = P_(secret, label + seed) // // The label is an ASCII string. static void prf_hmac_sha256( uint8_t *outbuf, unsigned outbuf_size, uint8_t *secret, unsigned secret_size, const char *label, uint8_t *seed, unsigned seed_size) { uint8_t a[SHA256_OUTSIZE]; uint8_t *out_p = outbuf; unsigned label_size = strlen(label); /* In P_hash() calculation, "seed" is "label + seed": */ #define SEED label, label_size, seed, seed_size #define SECRET secret, secret_size #define A a, (int)(sizeof(a)) /* A(1) = HMAC_hash(secret, seed) */ hmac_sha256(a, SECRET, SEED, NULL); //TODO: convert hmac_sha256 to precomputed for(;;) { /* HMAC_hash(secret, A(1) + seed) */ if (outbuf_size <= SHA256_OUTSIZE) { /* Last, possibly incomplete, block */ /* (use a[] as temp buffer) */ hmac_sha256(a, SECRET, A, SEED, NULL); memcpy(out_p, a, outbuf_size); return; } /* Not last block. Store directly to result buffer */ hmac_sha256(out_p, SECRET, A, SEED, NULL); out_p += SHA256_OUTSIZE; outbuf_size -= SHA256_OUTSIZE; /* A(2) = HMAC_hash(secret, A(1)) */ hmac_sha256(a, SECRET, A, NULL); } #undef A #undef SECRET #undef SEED } static tls_state_t *new_tls_state(void) { tls_state_t *tls = xzalloc(sizeof(*tls)); tls->fd = -1; sha256_begin(&tls->handshake_sha256_ctx); return tls; } static void tls_error_die(tls_state_t *tls) { dump_tls_record(tls->inbuf, tls->insize + tls->tail); xfunc_die(); } // RFC 5246 // 6.2.3.1. Null or Standard Stream Cipher // // Stream ciphers (including BulkCipherAlgorithm.null; see Appendix A.6) // convert TLSCompressed.fragment structures to and from stream // TLSCiphertext.fragment structures. // // stream-ciphered struct { // opaque content[TLSCompressed.length]; // opaque MAC[SecurityParameters.mac_length]; // } GenericStreamCipher; // // The MAC is generated as: // MAC(MAC_write_key, seq_num + // TLSCompressed.type + // TLSCompressed.version + // TLSCompressed.length + // TLSCompressed.fragment); // where "+" denotes concatenation. // seq_num // The sequence number for this record. // MAC // The MAC algorithm specified by SecurityParameters.mac_algorithm. // // Note that the MAC is computed before encryption. The stream cipher // encrypts the entire block, including the MAC. //... // Appendix C. Cipher Suite Definitions //... // Key IV Block // Cipher Type Material Size Size // ------------ ------ -------- ---- ----- // AES_128_CBC Block 16 16 16 // AES_256_CBC Block 32 16 16 // // MAC Algorithm mac_length mac_key_length // -------- ----------- ---------- -------------- // SHA HMAC-SHA1 20 20 // SHA256 HMAC-SHA256 32 32 static void xwrite_and_hash(tls_state_t *tls, /*const*/ void *buf, unsigned size) { uint8_t mac_hash[SHA256_OUTSIZE]; struct record_hdr *xhdr = buf; if (!tls->encrypt_on_write) { xwrite(tls->fd, buf, size); dbg("wrote %u bytes\n", size); /* Handshake hash does not include record headers */ if (size > 5 && xhdr->type == RECORD_TYPE_HANDSHAKE) { sha256_hash_dbg(">> sha256:%s", &tls->handshake_sha256_ctx, (uint8_t*)buf + 5, size - 5); } return; } //TODO: convert hmac_sha256 to precomputed hmac_sha256(mac_hash, tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key), &tls->write_seq64_be, sizeof(tls->write_seq64_be), buf, size, NULL); tls->write_seq64_be = SWAP_BE64(1 + SWAP_BE64(tls->write_seq64_be)); if (CIPHER_ID == TLS_RSA_WITH_NULL_SHA256) { /* No encryption, only signing */ xhdr->len16_lo += SHA256_OUTSIZE; //FIXME: overflow into len16_hi? xwrite(tls->fd, buf, size); xhdr->len16_lo -= SHA256_OUTSIZE; dbg("wrote %u bytes\n", size); xwrite(tls->fd, mac_hash, sizeof(mac_hash)); dbg("wrote %u bytes of hash\n", (int)sizeof(mac_hash)); return; } // RFC 5246 // 6.2.3.2. CBC Block Cipher // For block ciphers (such as 3DES or AES), the encryption and MAC // functions convert TLSCompressed.fragment structures to and from block // TLSCiphertext.fragment structures. // struct { // opaque IV[SecurityParameters.record_iv_length]; // block-ciphered struct { // opaque content[TLSCompressed.length]; // opaque MAC[SecurityParameters.mac_length]; // uint8 padding[GenericBlockCipher.padding_length]; // uint8 padding_length; // }; // } GenericBlockCipher; //... // IV // The Initialization Vector (IV) SHOULD be chosen at random, and // MUST be unpredictable. Note that in versions of TLS prior to 1.1, // there was no IV field (...). For block ciphers, the IV length is // of length SecurityParameters.record_iv_length, which is equal to the // SecurityParameters.block_size. // padding // Padding that is added to force the length of the plaintext to be // an integral multiple of the block cipher's block length. // padding_length // The padding length MUST be such that the total size of the // GenericBlockCipher structure is a multiple of the cipher's block // length. Legal values range from zero to 255, inclusive. //... // Appendix C. Cipher Suite Definitions //... // Key IV Block // Cipher Type Material Size Size // ------------ ------ -------- ---- ----- // AES_128_CBC Block 16 16 16 // AES_256_CBC Block 32 16 16 { psCipherContext_t ctx; uint8_t *p; uint8_t padding_length; /* Build IV+content+MAC+padding in outbuf */ tls_get_random(tls->outbuf, AES_BLOCKSIZE); /* IV */ p = tls->outbuf + AES_BLOCKSIZE; size -= sizeof(*xhdr); dbg("before crypt: 5 hdr + %u data + %u hash bytes\n", size, sizeof(mac_hash)); p = mempcpy(p, buf + sizeof(*xhdr), size); /* content */ p = mempcpy(p, mac_hash, sizeof(mac_hash)); /* MAC */ size += sizeof(mac_hash); // RFC is talking nonsense: // Padding that is added to force the length of the plaintext to be // an integral multiple of the block cipher's block length. // WRONG. _padding+padding_length_, not just _padding_, // pads the data. // IOW: padding_length is the last byte of padding[] array, // contrary to what RFC depicts. // // What actually happens is that there is always padding. // If you need one byte to reach BLOCKSIZE, this byte is 0x00. // If you need two bytes, they are both 0x01. // If you need three, they are 0x02,0x02,0x02. And so on. // If you need no bytes to reach BLOCKSIZE, you have to pad a full // BLOCKSIZE with bytes of value (BLOCKSIZE-1). // It's ok to have more than minimum padding, but we do minimum. padding_length = (~size) & (AES_BLOCKSIZE - 1); do { *p++ = padding_length; /* padding */ size++; } while ((size & (AES_BLOCKSIZE - 1)) != 0); /* Encrypt content+MAC+padding in place */ psAesInit(&ctx, tls->outbuf, /* IV */ tls->client_write_key, sizeof(tls->client_write_key) ); psAesEncrypt(&ctx, tls->outbuf + AES_BLOCKSIZE, /* plaintext */ tls->outbuf + AES_BLOCKSIZE, /* ciphertext */ size ); /* Write out */ dbg("writing 5 + %u IV + %u encrypted bytes, padding_length:0x%02x\n", AES_BLOCKSIZE, size, padding_length); size += AES_BLOCKSIZE; /* + IV */ xhdr->len16_hi = size >> 8; xhdr->len16_lo = size & 0xff; xwrite(tls->fd, xhdr, sizeof(*xhdr)); xwrite(tls->fd, tls->outbuf, size); dbg("wrote %u bytes\n", sizeof(*xhdr) + size); //restore xhdr->len16_hi = ; //restore xhdr->len16_lo = ; } } static int xread_tls_block(tls_state_t *tls) { struct record_hdr *xhdr; int sz; int total; int target; dbg("insize:%u tail:%u\n", tls->insize, tls->tail); memmove(tls->inbuf, tls->inbuf + tls->insize, tls->tail); errno = 0; total = tls->tail; target = sizeof(tls->inbuf); for (;;) { if (total >= sizeof(*xhdr) && target == sizeof(tls->inbuf)) { xhdr = (void*)tls->inbuf; target = sizeof(*xhdr) + (0x100 * xhdr->len16_hi + xhdr->len16_lo); if (target >= sizeof(tls->inbuf)) { /* malformed input (too long): yell and die */ tls->tail = 0; tls->insize = total; tls_error_die(tls); } // can also check type/proto_maj/proto_min here } /* if total >= target, we have a full packet (and possibly more)... */ if (total - target >= 0) break; sz = safe_read(tls->fd, tls->inbuf + total, sizeof(tls->inbuf) - total); if (sz <= 0) bb_perror_msg_and_die("short read"); total += sz; } tls->tail = total - target; tls->insize = target; sz = target - sizeof(*xhdr); /* Needs to be decrypted? */ if (tls->min_encrypted_len_on_read) { psCipherContext_t ctx; uint8_t *p = tls->inbuf + sizeof(*xhdr); int padding_len; if (sz & (AES_BLOCKSIZE-1) || sz < tls->min_encrypted_len_on_read ) { bb_error_msg_and_die("bad encrypted len:%u", sz); } /* Decrypt content+MAC+padding in place */ psAesInit(&ctx, p, /* IV */ tls->server_write_key, sizeof(tls->server_write_key) ); psAesDecrypt(&ctx, p + AES_BLOCKSIZE, /* ciphertext */ p + AES_BLOCKSIZE, /* plaintext */ sz ); padding_len = p[sz - 1]; dbg("encrypted size:%u type:0x%02x padding_length:0x%02x\n", sz, p[AES_BLOCKSIZE], padding_len); padding_len++; sz -= AES_BLOCKSIZE + SHA256_OUTSIZE + padding_len; if (sz < 0) { bb_error_msg_and_die("bad padding size:%u", padding_len); } if (sz != 0) { /* Skip IV */ memmove(tls->inbuf + 5, tls->inbuf + 5 + AES_BLOCKSIZE, sz); } } /* RFC 5246 is not saying it explicitly, but sha256 hash * in our FINISHED record must include data of incoming packets too! */ if (tls->inbuf[0] == RECORD_TYPE_HANDSHAKE) { sha256_hash_dbg("<< sha256:%s", &tls->handshake_sha256_ctx, tls->inbuf + 5, sz); } dbg("got block len:%u\n", sz); return sz; } /* * DER parsing routines */ static unsigned get_der_len(uint8_t **bodyp, uint8_t *der, uint8_t *end) { unsigned len, len1; if (end - der < 2) xfunc_die(); // if ((der[0] & 0x1f) == 0x1f) /* not single-byte item code? */ // xfunc_die(); len = der[1]; /* maybe it's short len */ if (len >= 0x80) { /* no, it's long */ if (len == 0x80 || end - der < (int)(len - 0x7e)) { /* 0x80 is "0 bytes of len", invalid DER: must use short len if can */ /* need 3 or 4 bytes for 81, 82 */ xfunc_die(); } len1 = der[2]; /* if (len == 0x81) it's "ii 81 xx", fetch xx */ if (len > 0x82) { /* >0x82 is "3+ bytes of len", should not happen realistically */ xfunc_die(); } if (len == 0x82) { /* it's "ii 82 xx yy" */ len1 = 0x100*len1 + der[3]; der += 1; /* skip [yy] */ } der += 1; /* skip [xx] */ len = len1; // if (len < 0x80) // xfunc_die(); /* invalid DER: must use short len if can */ } der += 2; /* skip [code]+[1byte] */ if (end - der < (int)len) xfunc_die(); *bodyp = der; return len; } static uint8_t *enter_der_item(uint8_t *der, uint8_t **endp) { uint8_t *new_der; unsigned len = get_der_len(&new_der, der, *endp); dbg_der("entered der @%p:0x%02x len:%u inner_byte @%p:0x%02x\n", der, der[0], len, new_der, new_der[0]); /* Move "end" position to cover only this item */ *endp = new_der + len; return new_der; } static uint8_t *skip_der_item(uint8_t *der, uint8_t *end) { uint8_t *new_der; unsigned len = get_der_len(&new_der, der, end); /* Skip body */ new_der += len; dbg_der("skipped der 0x%02x, next byte 0x%02x\n", der[0], new_der[0]); return new_der; } static void der_binary_to_pstm(pstm_int *pstm_n, uint8_t *der, uint8_t *end) { uint8_t *bin_ptr; unsigned len = get_der_len(&bin_ptr, der, end); dbg_der("binary bytes:%u, first:0x%02x\n", len, bin_ptr[0]); pstm_init_for_read_unsigned_bin(/*pool:*/ NULL, pstm_n, len); pstm_read_unsigned_bin(pstm_n, bin_ptr, len); //return bin + len; } static void find_key_in_der_cert(tls_state_t *tls, uint8_t *der, int len) { /* Certificate is a DER-encoded data structure. Each DER element has a length, * which makes it easy to skip over large compound elements of any complexity * without parsing them. Example: partial decode of kernel.org certificate: * SEQ 0x05ac/1452 bytes (Certificate): 308205ac * SEQ 0x0494/1172 bytes (tbsCertificate): 30820494 * [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0] 3 bytes: a003 * INTEGER (version): 0201 02 * INTEGER 0x11 bytes (serialNumber): 0211 00 9f85bf664b0cddafca508679501b2be4 * //^^^^^^note: matrixSSL also allows [ASN_CONTEXT_SPECIFIC | ASN_PRIMITIVE | 2] = 0x82 type * SEQ 0x0d bytes (signatureAlgo): 300d * OID 9 bytes: 0609 2a864886f70d01010b (OID_SHA256_RSA_SIG 42.134.72.134.247.13.1.1.11) * NULL: 0500 * SEQ 0x5f bytes (issuer): 305f * SET 11 bytes: 310b * SEQ 9 bytes: 3009 * OID 3 bytes: 0603 550406 * Printable string "FR": 1302 4652 * SET 14 bytes: 310e * SEQ 12 bytes: 300c * OID 3 bytes: 0603 550408 * Printable string "Paris": 1305 5061726973 * SET 14 bytes: 310e * SEQ 12 bytes: 300c * OID 3 bytes: 0603 550407 * Printable string "Paris": 1305 5061726973 * SET 14 bytes: 310e * SEQ 12 bytes: 300c * OID 3 bytes: 0603 55040a * Printable string "Gandi": 1305 47616e6469 * SET 32 bytes: 3120 * SEQ 30 bytes: 301e * OID 3 bytes: 0603 550403 * Printable string "Gandi Standard SSL CA 2": 1317 47616e6469205374616e646172642053534c2043412032 * SEQ 30 bytes (validity): 301e * TIME "161011000000Z": 170d 3136313031313030303030305a * TIME "191011235959Z": 170d 3139313031313233353935395a * SEQ 0x5b/91 bytes (subject): 305b //I did not decode this * 3121301f060355040b1318446f6d61696e20436f * 6e74726f6c2056616c6964617465643121301f06 * 0355040b1318506f73697469766553534c204d75 * 6c74692d446f6d61696e31133011060355040313 * 0a6b65726e656c2e6f7267 * SEQ 0x01a2/418 bytes (subjectPublicKeyInfo): 308201a2 * SEQ 13 bytes (algorithm): 300d * OID 9 bytes: 0609 2a864886f70d010101 (OID_RSA_KEY_ALG 42.134.72.134.247.13.1.1.1) * NULL: 0500 * BITSTRING 0x018f/399 bytes (publicKey): 0382018f * ????: 00 * //after the zero byte, it appears key itself uses DER encoding: * SEQ 0x018a/394 bytes: 3082018a * INTEGER 0x0181/385 bytes (modulus): 02820181 * 00b1ab2fc727a3bef76780c9349bf3 * ...24 more blocks of 15 bytes each... * 90e895291c6bc8693b65 * INTEGER 3 bytes (exponent): 0203 010001 * [ASN_CONTEXT_SPECIFIC | ASN_CONSTRUCTED | 0x3] 0x01e5 bytes (X509v3 extensions): a38201e5 * SEQ 0x01e1 bytes: 308201e1 * ... * Certificate is a sequence of three elements: * tbsCertificate (SEQ) * signatureAlgorithm (AlgorithmIdentifier) * signatureValue (BIT STRING) * * In turn, tbsCertificate is a sequence of: * version * serialNumber * signatureAlgo (AlgorithmIdentifier) * issuer (Name, has complex structure) * validity (Validity, SEQ of two Times) * subject (Name) * subjectPublicKeyInfo (SEQ) * ... * * subjectPublicKeyInfo is a sequence of: * algorithm (AlgorithmIdentifier) * publicKey (BIT STRING) * * We need Certificate.tbsCertificate.subjectPublicKeyInfo.publicKey */ uint8_t *end = der + len; /* enter "Certificate" item: [der, end) will be only Cert */ der = enter_der_item(der, &end); /* enter "tbsCertificate" item: [der, end) will be only tbsCert */ der = enter_der_item(der, &end); /* skip up to subjectPublicKeyInfo */ der = skip_der_item(der, end); /* version */ der = skip_der_item(der, end); /* serialNumber */ der = skip_der_item(der, end); /* signatureAlgo */ der = skip_der_item(der, end); /* issuer */ der = skip_der_item(der, end); /* validity */ der = skip_der_item(der, end); /* subject */ /* enter subjectPublicKeyInfo */ der = enter_der_item(der, &end); { /* check subjectPublicKeyInfo.algorithm */ static const uint8_t expected[] = { 0x30,0x0d, // SEQ 13 bytes 0x06,0x09, 0x2a,0x86,0x48,0x86,0xf7,0x0d,0x01,0x01,0x01, // OID RSA_KEY_ALG 42.134.72.134.247.13.1.1.1 //0x05,0x00, // NULL }; if (memcmp(der, expected, sizeof(expected)) != 0) bb_error_msg_and_die("not RSA key"); } /* skip subjectPublicKeyInfo.algorithm */ der = skip_der_item(der, end); /* enter subjectPublicKeyInfo.publicKey */ // die_if_not_this_der_type(der, end, 0x03); /* must be BITSTRING */ der = enter_der_item(der, &end); /* parse RSA key: */ //based on getAsnRsaPubKey(), pkcs1ParsePrivBin() is also of note dbg("key bytes:%u, first:0x%02x\n", (int)(end - der), der[0]); if (end - der < 14) xfunc_die(); /* example format: * ignore bits: 00 * SEQ 0x018a/394 bytes: 3082018a * INTEGER 0x0181/385 bytes (modulus): 02820181 XX...XXX * INTEGER 3 bytes (exponent): 0203 010001 */ if (*der != 0) /* "ignore bits", should be 0 */ xfunc_die(); der++; der = enter_der_item(der, &end); /* enter SEQ */ /* memset(tls->server_rsa_pub_key, 0, sizeof(tls->server_rsa_pub_key)); - already is */ der_binary_to_pstm(&tls->server_rsa_pub_key.N, der, end); /* modulus */ der = skip_der_item(der, end); der_binary_to_pstm(&tls->server_rsa_pub_key.e, der, end); /* exponent */ tls->server_rsa_pub_key.size = pstm_unsigned_bin_size(&tls->server_rsa_pub_key.N); dbg("server_rsa_pub_key.size:%d\n", tls->server_rsa_pub_key.size); } /* * TLS Handshake routines */ static int xread_tls_handshake_block(tls_state_t *tls, int min_len) { struct record_hdr *xhdr; int len = xread_tls_block(tls); xhdr = (void*)tls->inbuf; if (len < min_len || xhdr->type != RECORD_TYPE_HANDSHAKE || xhdr->proto_maj != TLS_MAJ || xhdr->proto_min != TLS_MIN ) { tls_error_die(tls); } dbg("got HANDSHAKE\n"); return len; } static void fill_handshake_record_hdr(struct record_hdr *xhdr, unsigned len) { struct handshake_hdr { struct record_hdr xhdr; uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; } *h = (void*)xhdr; h->xhdr.type = RECORD_TYPE_HANDSHAKE; h->xhdr.proto_maj = TLS_MAJ; h->xhdr.proto_min = TLS_MIN; len -= 5; h->xhdr.len16_hi = len >> 8; // can be optimized to do one store instead of four: // uint32_t v = htonl(0x100*(RECORD_TYPE_HANDSHAKE + 0x100*(TLS_MAJ + 0x100*(TLS_MIN)))) // | ((len >> 8) << 24); // little-endian specific, don't use in this form // *(uint32_t *)xhdr = v; h->xhdr.len16_lo = len & 0xff; len -= 4; h->len24_hi = len >> 16; h->len24_mid = len >> 8; h->len24_lo = len & 0xff; memset(h + 1, 0, len); } //TODO: implement RFC 5746 (Renegotiation Indication Extension) - some servers will refuse to work with us otherwise static void send_client_hello(tls_state_t *tls) { struct client_hello { struct record_hdr xhdr; uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; uint8_t proto_maj, proto_min; uint8_t rand32[32]; uint8_t session_id_len; /* uint8_t session_id[]; */ uint8_t cipherid_len16_hi, cipherid_len16_lo; uint8_t cipherid[2 * 1]; /* actually variable */ uint8_t comprtypes_len; uint8_t comprtypes[1]; /* actually variable */ }; struct client_hello record; fill_handshake_record_hdr(&record.xhdr, sizeof(record)); record.type = HANDSHAKE_CLIENT_HELLO; record.proto_maj = TLS_MAJ; /* the "requested" version of the protocol, */ record.proto_min = TLS_MIN; /* can be higher than one in record headers */ tls_get_random(record.rand32, sizeof(record.rand32)); /* record.session_id_len = 0; - already is */ /* record.cipherid_len16_hi = 0; */ record.cipherid_len16_lo = 2 * 1; record.cipherid[0] = CIPHER_ID >> 8; record.cipherid[1] = CIPHER_ID & 0xff; record.comprtypes_len = 1; /* record.comprtypes[0] = 0; */ //dbg (make it repeatable): memset(record.rand32, 0x11, sizeof(record.rand32)); dbg(">> CLIENT_HELLO\n"); xwrite_and_hash(tls, &record, sizeof(record)); memcpy(tls->client_and_server_rand32, record.rand32, sizeof(record.rand32)); } static void get_server_hello(tls_state_t *tls) { struct server_hello { struct record_hdr xhdr; uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; uint8_t proto_maj, proto_min; uint8_t rand32[32]; /* first 4 bytes are unix time in BE format */ uint8_t session_id_len; uint8_t session_id[32]; uint8_t cipherid_hi, cipherid_lo; uint8_t comprtype; /* extensions may follow, but only those which client offered in its Hello */ }; struct server_hello *hp; uint8_t *cipherid; xread_tls_handshake_block(tls, 74); hp = (void*)tls->inbuf; // 74 bytes: // 02 000046 03|03 58|78|cf|c1 50|a5|49|ee|7e|29|48|71|fe|97|fa|e8|2d|19|87|72|90|84|9d|37|a3|f0|cb|6f|5f|e3|3c|2f |20 |d8|1a|78|96|52|d6|91|01|24|b3|d6|5b|b7|d0|6c|b3|e1|78|4e|3c|95|de|74|a0|ba|eb|a7|3a|ff|bd|a2|bf |00|9c |00| //SvHl len=70 maj.min unixtime^^^ 28randbytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^_^^^ slen sid32bytes^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cipSel comprSel if (hp->type != HANDSHAKE_SERVER_HELLO || hp->len24_hi != 0 || hp->len24_mid != 0 /* hp->len24_lo checked later */ || hp->proto_maj != TLS_MAJ || hp->proto_min != TLS_MIN ) { tls_error_die(tls); } cipherid = &hp->cipherid_hi; if (hp->session_id_len != 32) { if (hp->session_id_len != 0) tls_error_die(tls); // session_id_len == 0: no session id // "The server // may return an empty session_id to indicate that the session will // not be cached and therefore cannot be resumed." cipherid -= 32; hp->len24_lo += 32; /* what len would be if session id would be present */ } if (hp->len24_lo < 70 || cipherid[0] != (CIPHER_ID >> 8) || cipherid[1] != (CIPHER_ID & 0xff) || cipherid[2] != 0 /* comprtype */ ) { tls_error_die(tls); } dbg("<< SERVER_HELLO\n"); memcpy(tls->client_and_server_rand32 + 32, hp->rand32, sizeof(hp->rand32)); } static void get_server_cert(tls_state_t *tls) { struct record_hdr *xhdr; uint8_t *certbuf; int len, len1; len = xread_tls_handshake_block(tls, 10); xhdr = (void*)tls->inbuf; certbuf = (void*)(xhdr + 1); if (certbuf[0] != HANDSHAKE_CERTIFICATE) tls_error_die(tls); dbg("<< CERTIFICATE\n"); // 4392 bytes: // 0b 00|11|24 00|11|21 00|05|b0 30|82|05|ac|30|82|04|94|a0|03|02|01|02|02|11|00|9f|85|bf|66|4b|0c|dd|af|ca|50|86|79|50|1b|2b|e4|30|0d... //Cert len=4388 ChainLen CertLen^ DER encoded X509 starts here. openssl x509 -in FILE -inform DER -noout -text len1 = get24be(certbuf + 1); if (len1 > len - 4) tls_error_die(tls); len = len1; len1 = get24be(certbuf + 4); if (len1 > len - 3) tls_error_die(tls); len = len1; len1 = get24be(certbuf + 7); if (len1 > len - 3) tls_error_die(tls); len = len1; if (len) find_key_in_der_cert(tls, certbuf + 10, len); } static void send_client_key_exchange(tls_state_t *tls) { struct client_key_exchange { struct record_hdr xhdr; uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; /* keylen16 exists for RSA (in TLS, not in SSL), but not for some other key types */ uint8_t keylen16_hi, keylen16_lo; uint8_t key[4 * 1024]; // size?? }; struct client_key_exchange record; uint8_t rsa_premaster[SSL_HS_RSA_PREMASTER_SIZE]; int len; fill_handshake_record_hdr(&record.xhdr, sizeof(record) - sizeof(record.key)); record.type = HANDSHAKE_CLIENT_KEY_EXCHANGE; tls_get_random(rsa_premaster, sizeof(rsa_premaster)); // RFC 5246 // "Note: The version number in the PreMasterSecret is the version // offered by the client in the ClientHello.client_version, not the // version negotiated for the connection." rsa_premaster[0] = TLS_MAJ; rsa_premaster[1] = TLS_MIN; len = psRsaEncryptPub(/*pool:*/ NULL, /* psRsaKey_t* */ &tls->server_rsa_pub_key, rsa_premaster, /*inlen:*/ sizeof(rsa_premaster), record.key, sizeof(record.key), data_param_ignored ); /* length fields need fixing */ record.keylen16_hi = len >> 8; record.keylen16_lo = len & 0xff; len += 2; /* record.len24_hi = 0; - already is */ record.len24_mid = len >> 8; record.len24_lo = len & 0xff; len += 4; record.xhdr.len16_hi = len >> 8; record.xhdr.len16_lo = len & 0xff; dbg(">> CLIENT_KEY_EXCHANGE\n"); xwrite_and_hash(tls, &record, sizeof(record.xhdr) + len); // RFC 5246 // For all key exchange methods, the same algorithm is used to convert // the pre_master_secret into the master_secret. The pre_master_secret // should be deleted from memory once the master_secret has been // computed. // master_secret = PRF(pre_master_secret, "master secret", // ClientHello.random + ServerHello.random) // [0..47]; // The master secret is always exactly 48 bytes in length. The length // of the premaster secret will vary depending on key exchange method. prf_hmac_sha256( tls->master_secret, sizeof(tls->master_secret), rsa_premaster, sizeof(rsa_premaster), "master secret", tls->client_and_server_rand32, sizeof(tls->client_and_server_rand32) ); dump_hex("master secret:%s\n", tls->master_secret, sizeof(tls->master_secret)); // RFC 5246 // 6.3. Key Calculation // // The Record Protocol requires an algorithm to generate keys required // by the current connection state (see Appendix A.6) from the security // parameters provided by the handshake protocol. // // The master secret is expanded into a sequence of secure bytes, which // is then split to a client write MAC key, a server write MAC key, a // client write encryption key, and a server write encryption key. Each // of these is generated from the byte sequence in that order. Unused // values are empty. Some AEAD ciphers may additionally require a // client write IV and a server write IV (see Section 6.2.3.3). // // When keys and MAC keys are generated, the master secret is used as an // entropy source. // // To generate the key material, compute // // key_block = PRF(SecurityParameters.master_secret, // "key expansion", // SecurityParameters.server_random + // SecurityParameters.client_random); // // until enough output has been generated. Then, the key_block is // partitioned as follows: // // client_write_MAC_key[SecurityParameters.mac_key_length] // server_write_MAC_key[SecurityParameters.mac_key_length] // client_write_key[SecurityParameters.enc_key_length] // server_write_key[SecurityParameters.enc_key_length] // client_write_IV[SecurityParameters.fixed_iv_length] // server_write_IV[SecurityParameters.fixed_iv_length] { uint8_t tmp64[64]; /* make "server_rand32 + client_rand32" */ memcpy(&tmp64[0] , &tls->client_and_server_rand32[32], 32); memcpy(&tmp64[32], &tls->client_and_server_rand32[0] , 32); prf_hmac_sha256( tls->client_write_MAC_key, 2 * (SHA256_OUTSIZE + AES256_KEYSIZE), // also fills: // server_write_MAC_key[SHA256_OUTSIZE] // client_write_key[AES256_KEYSIZE] // server_write_key[AES256_KEYSIZE] tls->master_secret, sizeof(tls->master_secret), "key expansion", tmp64, 64 ); dump_hex("client_write_MAC_key:%s\n", tls->client_write_MAC_key, sizeof(tls->client_write_MAC_key) ); dump_hex("client_write_key:%s\n", tls->client_write_key, sizeof(tls->client_write_key) ); } } static const uint8_t rec_CHANGE_CIPHER_SPEC[] = { RECORD_TYPE_CHANGE_CIPHER_SPEC, TLS_MAJ, TLS_MIN, 00, 01, 01 }; static void send_change_cipher_spec(tls_state_t *tls) { /* Not "xwrite_and_hash": this is not a handshake message */ dbg(">> CHANGE_CIPHER_SPEC\n"); xwrite(tls->fd, rec_CHANGE_CIPHER_SPEC, sizeof(rec_CHANGE_CIPHER_SPEC)); } // 7.4.9. Finished // A Finished message is always sent immediately after a change // cipher spec message to verify that the key exchange and // authentication processes were successful. It is essential that a // change cipher spec message be received between the other handshake // messages and the Finished message. //... // The Finished message is the first one protected with the just // negotiated algorithms, keys, and secrets. Recipients of Finished // messages MUST verify that the contents are correct. Once a side // has sent its Finished message and received and validated the // Finished message from its peer, it may begin to send and receive // application data over the connection. //... // struct { // opaque verify_data[verify_data_length]; // } Finished; // // verify_data // PRF(master_secret, finished_label, Hash(handshake_messages)) // [0..verify_data_length-1]; // // finished_label // For Finished messages sent by the client, the string // "client finished". For Finished messages sent by the server, // the string "server finished". // // Hash denotes a Hash of the handshake messages. For the PRF // defined in Section 5, the Hash MUST be the Hash used as the basis // for the PRF. Any cipher suite which defines a different PRF MUST // also define the Hash to use in the Finished computation. // // In previous versions of TLS, the verify_data was always 12 octets // long. In the current version of TLS, it depends on the cipher // suite. Any cipher suite which does not explicitly specify // verify_data_length has a verify_data_length equal to 12. This // includes all existing cipher suites. static void send_client_finished(tls_state_t *tls) { struct finished { struct record_hdr xhdr; uint8_t type; uint8_t len24_hi, len24_mid, len24_lo; uint8_t prf_result[12]; }; struct finished record; uint8_t handshake_hash[SHA256_OUTSIZE]; fill_handshake_record_hdr(&record.xhdr, sizeof(record)); record.type = HANDSHAKE_FINISHED; sha256_peek(&tls->handshake_sha256_ctx, handshake_hash); prf_hmac_sha256(record.prf_result, sizeof(record.prf_result), tls->master_secret, sizeof(tls->master_secret), "client finished", handshake_hash, sizeof(handshake_hash) ); dump_hex("from secret: %s\n", tls->master_secret, sizeof(tls->master_secret)); dump_hex("from labelSeed: %s", "client finished", sizeof("client finished")-1); dump_hex("%s\n", handshake_hash, sizeof(handshake_hash)); dump_hex("=> digest: %s\n", record.prf_result, sizeof(record.prf_result)); //(1) TODO: well, this should be encrypted on send, really. //(2) do we really need to also hash it? dbg(">> FINISHED\n"); xwrite_and_hash(tls, &record, sizeof(record)); } static void tls_handshake(tls_state_t *tls) { // Client RFC 5246 Server // (*) - optional messages, not always sent // // ClientHello -------> // ServerHello // Certificate* // ServerKeyExchange* // CertificateRequest* // <------- ServerHelloDone // Certificate* // ClientKeyExchange // CertificateVerify* // [ChangeCipherSpec] // Finished -------> // [ChangeCipherSpec] // <------- Finished // Application Data <------> Application Data int len; send_client_hello(tls); get_server_hello(tls); //RFC 5246 // The server MUST send a Certificate message whenever the agreed- // upon key exchange method uses certificates for authentication // (this includes all key exchange methods defined in this document // except DH_anon). This message will always immediately follow the // ServerHello message. // // IOW: in practice, Certificate *always* follows. // (for example, kernel.org does not even accept DH_anon cipher id) get_server_cert(tls); len = xread_tls_handshake_block(tls, 4); if (tls->inbuf[5] == HANDSHAKE_SERVER_KEY_EXCHANGE) { // 459 bytes: // 0c 00|01|c7 03|00|17|41|04|87|94|2e|2f|68|d0|c9|f4|97|a8|2d|ef|ed|67|ea|c6|f3|b3|56|47|5d|27|b6|bd|ee|70|25|30|5e|b0|8e|f6|21|5a... //SvKey len=455^ // with TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA: 461 bytes: // 0c 00|01|c9 03|00|17|41|04|cd|9b|b4|29|1f|f6|b0|c2|84|82|7f|29|6a|47|4e|ec|87|0b|c1|9c|69|e1|f8|c6|d0|53|e9|27|90|a5|c8|02|15|75... dbg("<< SERVER_KEY_EXCHANGE len:%u\n", len); //probably need to save it xread_tls_handshake_block(tls, 4); } // if (tls->inbuf[5] == HANDSHAKE_CERTIFICATE_REQUEST) { // dbg("<< CERTIFICATE_REQUEST\n"); //RFC 5246: (in response to this,) "If no suitable certificate is available, // the client MUST send a certificate message containing no // certificates. That is, the certificate_list structure has a // length of zero. ... // Client certificates are sent using the Certificate structure // defined in Section 7.4.2." // (i.e. the same format as server certs) // xread_tls_handshake_block(tls, 4); // } if (tls->inbuf[5] != HANDSHAKE_SERVER_HELLO_DONE) tls_error_die(tls); // 0e 000000 (len:0) dbg("<< SERVER_HELLO_DONE\n"); send_client_key_exchange(tls); send_change_cipher_spec(tls); /* from now on we should send encrypted */ /* tls->write_seq64_be = 0; - already is */ tls->encrypt_on_write = 1; send_client_finished(tls); /* Get CHANGE_CIPHER_SPEC */ len = xread_tls_block(tls); if (len != 1 || memcmp(tls->inbuf, rec_CHANGE_CIPHER_SPEC, 6) != 0) tls_error_die(tls); dbg("<< CHANGE_CIPHER_SPEC\n"); /* all incoming packets now should be encrypted and have IV + MAC + padding */ tls->min_encrypted_len_on_read = AES_BLOCKSIZE + SHA256_OUTSIZE + AES_BLOCKSIZE; /* Get (encrypted) FINISHED from the server */ len = xread_tls_block(tls); if (len < 4 || tls->inbuf[5] != HANDSHAKE_FINISHED) tls_error_die(tls); dbg("<< FINISHED\n"); /* application data can be sent/received */ } // To run a test server using openssl: // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost' // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 // // Unencryped SHA256 example: // openssl req -x509 -newkey rsa:$((4096/4*3)) -keyout key.pem -out server.pem -nodes -days 99999 -subj '/CN=localhost' // openssl s_server -key key.pem -cert server.pem -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL // openssl s_client -connect 127.0.0.1:4433 -debug -tls1_2 -no_tls1 -no_tls1_1 -cipher NULL-SHA256 int tls_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int tls_main(int argc UNUSED_PARAM, char **argv) { tls_state_t *tls; len_and_sockaddr *lsa; int fd; // INIT_G(); // getopt32(argv, "myopts") if (!argv[1]) bb_show_usage(); lsa = xhost2sockaddr(argv[1], 443); fd = xconnect_stream(lsa); tls = new_tls_state(); tls->fd = fd; tls_handshake(tls); return EXIT_SUCCESS; } /* Unencryped SHA256 example: * s_client says: write to 0x1d750b0 [0x1e6f153] (99 bytes => 99 (0x63)) 0000 - 16 03 01 005e 01 00005a 0303 [4d ef 5c 82 3e ....^...Z..M.\.> >> ClHello 0010 - bf a6 ee f1 1e 04 d1 5c-99 20 86 13 e9 0a cf 58 .......\. .....X 0020 - 75 b1 bd 7a e6 d6 44 f3-d3 a1 52] 00 0004 003b u..z..D...R....; 003b = TLS_RSA_WITH_NULL_SHA256 0030 - 00ff TLS_EMPTY_RENEGOTIATION_INFO_SCSV 0100 compr=none 002d, 0023 0000, 000d 0020 [00 1e .....-.#..... .. extlen, SessionTicketTLS 0 bytes, SignatureAlgorithms 32 bytes 0040 - 06 01 06 02 06 03 05 01-05 02 05 03 04 01 04 02 ................ 0050 - 04 03 03 01 03 02 03 03-02 01 02 02 02 03] 000f ................ Heart Beat 1 byte 0060 - 0001 01 ... read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 16 03 03 00 3a ....: read from 0x1d750b0 [0x1e6ac08] (58 bytes => 58 (0x3A)) 0000 - 02 000036 0303 [f2 61-ae c8 58 e3 51 42 32 93 ...6...a..X.QB2. << SvHello 0010 - c5 62 e4 f5 06 93 81 65-aa f7 df 74 af 7c 98 b4 .b.....e...t.|.. 0020 - 3e a7 35 c3 25 69] 00,003b,00.................. >.5.%i..;....... - no session id! "The server may return an empty session_id to indicate that the session will not be cached and therefore cannot be resumed." 003b = TLS_RSA_WITH_NULL_SHA256 accepted, 00 - no compr 000e ff01 0001 extlen, 0xff01=RenegotiationInfo 1 byte 0030 - 00, 0023 0000, SessionTicketTLS 0 bytes 000f 0001 01 ..#....... Heart Beat 1 byte read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 16 03 03 04 0b ..... read from 0x1d750b0 [0x1e6ac08] (1035 bytes => 1035 (0x40B)) 0000 - 0b 00 04 07 00 04 04 00-04 01 30 82 03 fd 30 82 ..........0...0. << Cert 0010 - 02 65 a0 03 02 01 02 02-09 00 d9 d9 8d b8 94 ad .e.............. 0020 - 2e 2b 30 0d 06 09 2a 86-48 86 f7 0d 01 01 0b 05 .+0...*.H....... 0030 - 00 30 14 31 12 30 10 06-03 55 04 03 0c 09 6c 6f .0.1.0...U....lo 0040 - 63 61 6c 68 6f 73 74 30-20 17 0d 31 37 30 31 31 calhost0 ..17011 ..."......."......."......."......."......."......."......."......."..... 03f0 - 11 8a cd c5 a3 0a 22 43-d5 13 f9 a5 8a 06 f9 00 ......"C........ 0400 - 3c f7 86 4e e8 a5 d8 5b-92 37 f5 <..N...[.7. depth=0 CN = localhost verify error:num=18:self signed certificate verify return:1 depth=0 CN = localhost verify return:1 read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 16 03 03 00 04 ..... read from 0x1d750b0 [0x1e6ac08] (4 bytes => 4 (0x4)) << SvDone 0000 - 0e . 0004 - write to 0x1d750b0 [0x1e74620] (395 bytes => 395 (0x18B)) >> ClDone 0000 - 16 03 03 01 86 10 00 01-82 01 80 88 f0 87 5d b0 ..............]. 0010 - ea df 3b 4d e2 35 f3 99-e6 d4 29 87 36 86 ea 30 ..;M.5....).6..0 0020 - 38 80 c7 37 66 7f 5b e7-23 38 7e 87 24 66 82 81 8..7f.[.#8~.$f.. 0030 - e4 ba 6c 2a 0c 92 a8 b9-39 c1 55 16 32 88 14 cd ..l*....9.U.2... 0040 - 95 8c 82 49 a1 c7 f9 9b-e5 8f f6 5e 7e ee 91 b3 ...I.......^~... 0050 - 2c 92 e7 a3 02 f8 9f 56-04 45 39 df a7 d6 1a 16 ,......V.E9..... 0060 - 67 5c a4 f8 87 8a c4 c8-6c 6f c6 f0 9b c9 b4 87 g\......lo...... 0070 - 36 43 c1 67 9f b3 aa 11-34 b0 c2 fc 1f d9 e1 ff 6C.g....4....... 0080 - fb e1 89 db 91 58 ec cc-aa 16 19 9a 91 74 e2 46 .....X.......t.F 0090 - 22 a7 a7 f7 9e 3c 97 82-2c e4 21 b3 fa ef ba 3f "....<..,.!....? 00a0 - 57 48 e4 b2 84 b7 c2 81-92 a9 f1 03 68 f4 e6 0c WH..........h... 00b0 - fd 54 87 f5 e9 a0 5d e6-5f 0e bd 80 86 27 ab 0e .T....]._....'.. 00c0 - cf 92 4f bd fc 24 b9 54-72 5f 58 df 6b 2b 1d 97 ..O..$.Tr_X.k+.. 00d0 - 00 60 fe 95 b0 aa d6 c7-c1 3a f9 2e 7c 92 a9 6d .`.......:..|..m 00e0 - 28 a3 ef 3e c1 e6 2d 2d-e8 db 81 ea 51 02 3f 64 (..>..--....Q.?d 00f0 - a8 66 14 c1 4b 17 1f 55-c6 5b 3b 38 c3 6a 61 a8 .f..K..U.[;8.ja. 0100 - f7 ad 65 7d cb 14 6d b3-0f 76 19 25 8e ed bd 53 ..e}..m..v.%...S 0110 - 35 a9 a1 34 00 9d 07 81-84 51 35 e0 83 83 e3 a6 5..4.....Q5..... 0120 - c7 77 4c 61 e4 78 9c cb-f5 92 4e d6 dd c4 c2 2b .wLa.x....N....+ 0130 - 75 9e 72 a6 7f 81 6a 1c-fc 4a 51 91 81 b4 cc 33 u.r...j..JQ....3 0140 - 1c 8b 0a b6 94 8b 16 1b-86 2f 31 5e 31 e1 57 14 ........./1^1.W. 0150 - 2e b5 09 5d cf 6f ea b2-94 e9 5c cc b9 fc 24 a0 ...].o....\...$. 0160 - b7 f1 f4 9d 95 46 4f 08-5c 45 c6 2f 9f 7d 76 09 .....FO.\E./.}v. 0170 - 6a af 50 2c 89 76 82 5f-e8 34 d8 4b 84 b6 34 18 j.P,.v._.4.K..4. 0180 - 85 95 4a 3f 0f 28 88 3a-71 32 90 ..J?.(.:q2. write to 0x1d750b0 [0x1e74620] (6 bytes => 6 (0x6)) 0000 - 14 03 03 00 01 01 ...... >> CHANGE_CIPHER_SPEC write to 0x1d750b0 [0x1e74620] (53 bytes => 53 (0x35)) 0000 - 16 03 03 0030 14 00000c [ed b9 e1 33 36 0b 76 ....0.......36.v >> FINISHED (0x14) [PRF 12 bytes|SHA256_OUTSIZE 32 bytes] 0010 - c0 d1 d4 0b a3|73 ec a8-fa b5 cb 12 b6 4c 2a b1 .....s.......L*. 0020 - fb 42 7f 73 0d 06 1c 87-56 f0 db df e6 6a 25 aa .B.s....V....j%. 0030 - fc 42 38 cb 0b] .B8.. read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 16 03 03 00 aa ..... read from 0x1d750b0 [0x1e6ac08] (170 bytes => 170 (0xAA)) 0000 - 04 00 00 a6 00 00 1c 20-00 a0 dd f4 52 01 54 8d ....... ....R.T. << NEW_SESSION_TICKET 0010 - f8 a6 f9 2d 7d 19 20 5b-14 44 d3 2d 7b f2 ca e8 ...-}. [.D.-{... 0020 - 01 4e 94 7b fe 12 59 3a-00 2e 7e cf 74 43 7a f7 .N.{..Y:..~.tCz. 0030 - 9e cc 70 80 70 7c e3 a5-c6 9d 85 2c 36 19 4c 5c ..p.p|.....,6.L\ 0040 - ba 3b c3 e5 69 dc f3 a4-47 38 11 c9 7d 1a b0 6e .;..i...G8..}..n 0050 - d8 49 a0 a8 e4 de 70 a8-d0 6b e4 7a b7 65 25 df .I....p..k.z.e%. 0060 - 1b 5f 64 0f 89 69 02 72-fe eb d3 7a af 51 78 0e ._d..i.r...z.Qx. 0070 - de 17 06 a5 f0 47 9d e0-04 d4 b1 1e be 7e ed bd .....G.......~.. 0080 - 27 8f 5d e8 ac f6 45 aa-e0 12 93 41 5f a8 4b b9 '.]...E....A_.K. 0090 - bd 43 8f a1 23 51 af 92-77 8f 38 23 3e 2e c2 f0 .C..#Q..w.8#>... 00a0 - a3 74 fa 83 94 ce 19 8a-5b 5b .t......[[ read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 14 03 03 00 01 ..... << CHANGE_CIPHER_SPEC read from 0x1d750b0 [0x1e6ac08] (1 bytes => 1 (0x1)) 0000 - 01 . read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 16 03 03 00 30 ....0 read from 0x1d750b0 [0x1e6ac08] (48 bytes => 48 (0x30)) 0000 - 14 00000c [06 86 0d 5c-92 0b 63 04 cc b4 f0 00 .......\..c..... << FINISHED (0x14) [PRF 12 bytes|SHA256_OUTSIZE 32 bytes] 0010 -|49 d6 dd 56 73 e3 d2 e8-22 d6 bd 61 b2 b3 af f0 I..Vs..."..a.... 0020 - f5 00 8a 80 82 04 33 a7-50 8e ae 3b 4c 8c cf 4a] ......3.P..;L..J --- Certificate chain 0 s:/CN=localhost i:/CN=localhost --- Server certificate -----BEGIN CERTIFICATE----- ..."......."......."......."......."......."......."......."......."..... -----END CERTIFICATE----- subject=/CN=localhost issuer=/CN=localhost --- No client certificate CA names sent --- SSL handshake has read 1346 bytes and written 553 bytes --- New, TLSv1/SSLv3, Cipher is NULL-SHA256 Server public key is 3072 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE No ALPN negotiated SSL-Session: Protocol : TLSv1.2 Cipher : NULL-SHA256 Session-ID: 5D62B36950F3DEB571707CD1B815E9E275041B9DB70D7F3E25C4A6535B13B616 Session-ID-ctx: Master-Key: 4D08108C59417E0A41656636C51BA5B83F4EFFF9F4C860987B47B31250E5D1816D00940DBCCC196C2D99C8462C889DF1 Key-Arg : None Krb5 Principal: None PSK identity: None PSK identity hint: None TLS session ticket lifetime hint: 7200 (seconds) TLS session ticket: 0000 - dd f4 52 01 54 8d f8 a6-f9 2d 7d 19 20 5b 14 44 ..R.T....-}. [.D 0010 - d3 2d 7b f2 ca e8 01 4e-94 7b fe 12 59 3a 00 2e .-{....N.{..Y:.. 0020 - 7e cf 74 43 7a f7 9e cc-70 80 70 7c e3 a5 c6 9d ~.tCz...p.p|.... 0030 - 85 2c 36 19 4c 5c ba 3b-c3 e5 69 dc f3 a4 47 38 .,6.L\.;..i...G8 0040 - 11 c9 7d 1a b0 6e d8 49-a0 a8 e4 de 70 a8 d0 6b ..}..n.I....p..k 0050 - e4 7a b7 65 25 df 1b 5f-64 0f 89 69 02 72 fe eb .z.e%.._d..i.r.. 0060 - d3 7a af 51 78 0e de 17-06 a5 f0 47 9d e0 04 d4 .z.Qx......G.... 0070 - b1 1e be 7e ed bd 27 8f-5d e8 ac f6 45 aa e0 12 ...~..'.]...E... 0080 - 93 41 5f a8 4b b9 bd 43-8f a1 23 51 af 92 77 8f .A_.K..C..#Q..w. 0090 - 38 23 3e 2e c2 f0 a3 74-fa 83 94 ce 19 8a 5b 5b 8#>....t......[[ Start Time: 1484574330 Timeout : 7200 (sec) Verify return code: 18 (self signed certificate) --- read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 17 03 03 00 21 ....! read from 0x1d750b0 [0x1e6ac08] (33 bytes => 33 (0x21)) 0000 - 0a 74 5b 50 02 13 75 a4-27 0a 40 b1 53 74 52 14 .t[P..u.'.@.StR. 0010 - e7 1e 6a 6c c1 60 2e 93-7e a5 d9 43 1d 8e f6 08 ..jl.`..~..C.... 0020 - 69 i read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 17 03 03 00 21 ....! read from 0x1d750b0 [0x1e6ac08] (33 bytes => 33 (0x21)) 0000 - 0a 1b ce 44 98 4f 81 c5-28 7a cc 79 62 db d2 86 ...D.O..(z.yb... 0010 - 6a 55 a4 c7 73 49 ef 3e-bd 03 99 76 df 65 2a a1 jU..sI.>...v.e*. 0020 - b6 . read from 0x1d750b0 [0x1e6ac03] (5 bytes => 5 (0x5)) 0000 - 17 03 03 00 21 ....! read from 0x1d750b0 [0x1e6ac08] (33 bytes => 33 (0x21)) 0000 - 0a 67 66 34 ba 68 36 3c-ad 0a c1 f5 c0 5a 50 fe .gf4.h6<.....ZP. 0010 - 68 cd 04 65 e9 de 6e 98-f9 e2 41 1e 0b 9b 84 06 h..e..n...A..... 0020 - 64 d */