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Author SHA1 Message Date
xtaciandGitHub baf532e1b1 Update README.md 2018-10-27 21:56:36 +08:00
xtaci c5cdc30250 add wechat_donate 2018-10-27 21:51:25 +08:00
xtaciandGitHub d0eafa4cce Merge pull request #625 from HaraldNordgren/master
Bump Travis versions
2018-10-20 12:23:51 +08:00
Harald Nordgren 3ac0c05756 Bump Travis versions 2018-10-19 21:48:36 +02:00
xtaciandGitHub 1bcb40d3fe Update README.md 2018-10-16 01:42:44 +08:00
xtaci 962f8c4a31 rm rs.png 2018-10-15 17:05:06 +08:00
xtaci cba4bbefd4 upd FEC.png 2018-10-15 17:01:47 +08:00
xtaci a3f60e5781 update FEC diagram 2018-10-15 16:59:44 +08:00
xtaciandGitHub e31a6cfca3 Update README.md 2018-10-08 13:53:57 +08:00
xtaciandGitHub 79deb2ab86 Update README.md 2018-10-05 23:36:52 +08:00
xtaciandGitHub 6cc274e01e Update README.md 2018-10-05 23:07:18 +08:00
xtaciandGitHub b0620ab7a2 Update README.md
elaborate crypto analysis
2018-10-05 22:55:54 +08:00
xtaciandGitHub b4e4d747e7 Update README.md 2018-10-04 23:52:33 +08:00
5 changed files with 56 additions and 27 deletions
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@@ -1,6 +1,8 @@
language: go
go:
- 1.9
- 1.9.x
- 1.10.x
- 1.11.x
before_install:
- go get github.com/mattn/goveralls
- go get golang.org/x/tools/cmd/cover
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<img src="kcptun.png" alt="kcptun" height="300px"/>
> *kcptun maintains a single website — [github.com/xtaci/kcptun](https://github.com/xtaci/kcptun). Any websites other than [github.com/xtaci/kcptun](https://github.com/xtaci/kcptun) are not endorsed by xtaci. kcptun won't publish anything on any social media.*
> *Disclaimer: kcptun maintains a single website — [github.com/xtaci/kcptun](https://github.com/xtaci/kcptun). Any websites other than [github.com/xtaci/kcptun](https://github.com/xtaci/kcptun) are not endorsed by xtaci.*
> *KCP discussion QQ group: 364933586, KCP integration, tuning, network transmission and related technical discussions.*
@@ -45,7 +45,7 @@ You can also increase the per-socket buffer by adding parameter(default 4MB):
increasing this would work for most of the old model CPUs.
Download a corresponding precompiled [Releases](https://github.com/xtaci/kcptun/releases).
Download a corresponding one from precompiled [Releases](https://github.com/xtaci/kcptun/releases).
```
KCP Client: ./client_darwin_amd64 -r "KCP_SERVER_IP:4000" -l ":8388" -mode fast2
@@ -182,11 +182,11 @@ GLOBAL OPTIONS:
#### Forward Error Correction
In coding theory, the ReedSolomon code belongs to the class of non-binary cyclic error-correcting codes. The ReedSolomon code is based on univariate polynomials over finite fields.
In coding theory, the [ReedSolomon code](https://en.wikipedia.org/wiki/Reed%E2%80%93Solomon_error_correction) belongs to the class of non-binary cyclic error-correcting codes. The ReedSolomon code is based on univariate polynomials over finite fields.
It is able to detect and correct multiple symbol errors. By adding t check symbols to the data, a ReedSolomon code can detect any combination of up to t erroneous symbols, or correct up to ⌊t/2⌋ symbols. As an erasure code, it can correct up to t known erasures, or it can detect and correct combinations of errors and erasures. Furthermore, ReedSolomon codes are suitable as multiple-burst bit-error correcting codes, since a sequence of b + 1 consecutive bit errors can affect at most two symbols of size b. The choice of t is up to the designer of the code, and may be selected within wide limits.
![reed-solomon](rs.png)
![FED](FEC.png)
Setting parameters of RS-Code with ```-datashard m -parityshard n``` on **BOTH** KCP Client & KCP Server **MUST** be **IDENTICAL**.
@@ -198,35 +198,58 @@ DiffServ uses a 6-bit differentiated services code point (DSCP) in the 8-bit dif
setting each side with ```-dscp value```, Here are some [Commonly used DSCP values](https://en.wikipedia.org/wiki/Differentiated_services#Commonly_used_DSCP_values).
#### Security
#### Cryptanalysis
No matter what encryption you are using for application layer, if you specify ```-crypt none``` to kcptun,
the header will be ***PLAINTEXT*** to everyone; I suggest ```-crypt aes-128``` for encryption at least .
kcptun is shipped with builtin packet encryption powered by various block encryption algorithms and works in [Cipher Feedback Mode](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher_Feedback_(CFB)), for each packet to be sent, the encryption process will start from encrypting a [nonce](https://en.wikipedia.org/wiki/Cryptographic_nonce) from the [system entropy](https://en.wikipedia.org/wiki//dev/random), so encryption to same plaintexts never leads to a same ciphertexts thereafter.
`-crypt` and `-key` must be the same on both KCP Client & KCP Server.
The contents of the packets are completely anonymous with encryption, including the headers(FEC,KCP), checksums and contents. Note that, no matter which encryption method you choose on you upper layer, if you disable encryption by specifying `-crypt none` to kcptun, the transmit will be insecure somehow, since the header is ***PLAINTEXT*** to everyone it would be susceptible to header tampering, such as jamming the *sliding window size*, *round-trip time*, *FEC property* and *checksums*. ```aes-128``` is suggested for minimal encryption since modern CPUs are shipped with [AES-NI](https://en.wikipedia.org/wiki/AES_instruction_set) instructions and performs even better than `salsa20`(check the table below).
NOTICE: ```-crypt xor``` is also insecure, do not use this unless you know what you are doing.
Other possible attacks to kcptun includes: a) [traffic analysis](https://en.wikipedia.org/wiki/Traffic_analysis), dataflow on specific websites may have pattern while interchanging data, but this type of eavesdropping has been mitigated by adapting [smux](https://github.com/xtaci/smux) to mix data streams so as to introduce noises, perfect solution to this has not appeared yet, theroretically by shuffling/mixing messages on larger scale network may mitigate this problem. b) [replay attack](https://en.wikipedia.org/wiki/Replay_attack), since the asymmetrical encryption has not been introduced into kcptun for some reason, capturing the packets and replay them on a different machine is possible, (notice: hijacking the session and decrypting the contents is still *impossible*), so upper layers should contain a asymmetrical encryption system to guarantee the authenticity of each message(to process message exactly once), such as HTTPS/OpenSSL/LibreSSL, only by signing the requests with private keys can eliminate this type of attack.
Important:
1. `-crypt` and `-key` must be the same on both KCP Client & KCP Server.
2. `-crypt xor` is also insecure and vulnerable to [known-plaintext attack](https://en.wikipedia.org/wiki/Known-plaintext_attack), do not use this unless you know what you are doing. (*cryptanalysis note: any type of [counter mode](https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Counter_(CTR)) is insecure in packet encryption due to the shorten of counter period and leads to iv/nonce collision*)
Benchmarks for crypto algorithms supported by kcptun:
```
BenchmarkAES128-4 200000 11182 ns/op
BenchmarkAES192-4 200000 12699 ns/op
BenchmarkAES256-4 100000 13757 ns/op
BenchmarkTEA-4 50000 26441 ns/op
BenchmarkSimpleXOR-4 3000000 441 ns/op
BenchmarkBlowfish-4 30000 48036 ns/op
BenchmarkNone-4 20000000 106 ns/op
BenchmarkCast5-4 20000 60222 ns/op
BenchmarkTripleDES-4 2000 878759 ns/op
BenchmarkTwofish-4 20000 68501 ns/op
BenchmarkXTEA-4 20000 77417 ns/op
BenchmarkSalsa20-4 300000 4998 ns/op
BenchmarkSM4-4 50000 32087 ns/op 93.49 MB/s 0 B/op 0 allocs/op
BenchmarkAES128-4 500000 3274 ns/op 916.15 MB/s 0 B/op 0 allocs/op
BenchmarkAES192-4 500000 3587 ns/op 836.34 MB/s 0 B/op 0 allocs/op
BenchmarkAES256-4 300000 3828 ns/op 783.60 MB/s 0 B/op 0 allocs/op
BenchmarkTEA-4 100000 15359 ns/op 195.32 MB/s 0 B/op 0 allocs/op
BenchmarkXOR-4 20000000 90.2 ns/op 33249.02 MB/s 0 B/op 0 allocs/op
BenchmarkBlowfish-4 50000 26885 ns/op 111.58 MB/s 0 B/op 0 allocs/op
BenchmarkNone-4 30000000 45.8 ns/op 65557.11 MB/s 0 B/op 0 allocs/op
BenchmarkCast5-4 50000 34370 ns/op 87.29 MB/s 0 B/op 0 allocs/op
Benchmark3DES-4 10000 117893 ns/op 25.45 MB/s 0 B/op 0 allocs/op
BenchmarkTwofish-4 50000 33477 ns/op 89.61 MB/s 0 B/op 0 allocs/op
BenchmarkXTEA-4 30000 45825 ns/op 65.47 MB/s 0 B/op 0 allocs/op
BenchmarkSalsa20-4 500000 3282 ns/op 913.90 MB/s 0 B/op 0 allocs/op
```
Benchmark result from openssl
```
$ openssl speed -evp aes-128-cfb
Doing aes-128-cfb for 3s on 16 size blocks: 157794127 aes-128-cfb's in 2.98s
Doing aes-128-cfb for 3s on 64 size blocks: 39614018 aes-128-cfb's in 2.98s
Doing aes-128-cfb for 3s on 256 size blocks: 9971090 aes-128-cfb's in 2.99s
Doing aes-128-cfb for 3s on 1024 size blocks: 2510877 aes-128-cfb's in 2.99s
Doing aes-128-cfb for 3s on 8192 size blocks: 310865 aes-128-cfb's in 2.98s
OpenSSL 1.0.2p 14 Aug 2018
built on: reproducible build, date unspecified
options:bn(64,64) rc4(ptr,int) des(idx,cisc,16,int) aes(partial) idea(int) blowfish(idx)
compiler: clang -I. -I.. -I../include -fPIC -fno-common -DOPENSSL_PIC -DOPENSSL_THREADS -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -arch x86_64 -O3 -DL_ENDIAN -Wall -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DWHIRLPOOL_ASM -DGHASH_ASM -DECP_NISTZ256_ASM
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
aes-128-cfb 847216.79k 850770.86k 853712.05k 859912.39k 854565.80k
```
The encrytion performance in kcptun is as fast as in openssl library(if not faster).
#### Memory Control
#### Memory Usage Control
Routers, mobile devices are susceptible to memory consumption; by setting GOGC environment(eg: GOGC=20) will make the garbage collector to recycle faster.
Reference: https://blog.golang.org/go15gc
@@ -244,7 +267,7 @@ kcptun has builtin snappy algorithms for compressing streams:
> Reference: http://google.github.io/snappy/
Compression may save bandwidth for **PLAINTEXT** data, such as HTTP data.
Compression may save bandwidth for **PLAINTEXT** data, it's quite useful for specific scenarios as cross-datacenter replications, by compressing the redologs in dbms or kafka-like message queues and then transfer the data streams across the continent can be much faster.
Compression is enabled by default, you can disable it by setting ```-nocomp``` on **BOTH** KCP Client & KCP Server **MUST** be **IDENTICAL**.
@@ -318,8 +341,12 @@ The parameters below **MUST** be **IDENTICAL** on **BOTH** side:
1. https://en.wikipedia.org/wiki/Noisy-channel_coding_theorem -- Noisy channel coding theorem
1. https://play.google.com/store/apps/details?id=com.k17game.k3 -- Battle Zone - Earth 2048, an online strategy game using kcp.
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Address: 0x2e4b43ab3d0983da282592571eef61ae5e60f726 , Or scan here:
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