In message <1e19cdfea8224717b3eee11e2d8ac...@usma1ex-dag1mb1.msg.corp.akamai.com> on Wed, 11 Jan 2017 03:13:39 +0000, "Salz, Rich" <rs...@akamai.com> said:
rsalz> The needs for OpenSSL's LHASH are exactly what SipHash was designed for: fast on short strings. rsalz> OpenSSL's hash currently *does not* call MD5 or SHA1; the MD5 code is commented out. rsalz> Yes, performance tests would greatly inform the decision. Done, using the reference siphash implementation. https://github.com/levitte/openssl/tree/test-string-hashes A run on my laptop gave these results: : ; ./util/shlib_wrap.sh apps/openssl speed siphash lhash Doing lhash for 3s on 16 size blocks: 27635188 lhash's in 3.00s Doing lhash for 3s on 64 size blocks: 6934726 lhash's in 3.00s Doing lhash for 3s on 256 size blocks: 1698489 lhash's in 3.00s Doing lhash for 3s on 1024 size blocks: 431185 lhash's in 3.00s Doing lhash for 3s on 8192 size blocks: 53868 lhash's in 3.00s Doing lhash for 3s on 16384 size blocks: 27041 lhash's in 3.00s Doing siphash for 3s on 16 size blocks: 22488748 siphash's in 3.00s Doing siphash for 3s on 64 size blocks: 10485674 siphash's in 3.00s Doing siphash for 3s on 256 size blocks: 3320898 siphash's in 3.00s Doing siphash for 3s on 1024 size blocks: 894647 siphash's in 3.00s Doing siphash for 3s on 8192 size blocks: 114170 siphash's in 3.00s Doing siphash for 3s on 16384 size blocks: 57151 siphash's in 3.00s OpenSSL 1.1.1-dev xx XXX xxxx built on: reproducible build, date unspecified options:bn(64,64) rc4(16x,int) des(int) aes(partial) idea(int) blowfish(ptr) compiler: gcc -DDSO_DLFCN -DHAVE_DLFCN_H -DOPENSSL_THREADS -DOPENSSL_NO_STATIC_ENGINE -DOPENSSL_PIC -DOPENSSL_IA32_SSE2 -DOPENSSL_BN_ASM_MONT -DOPENSSL_BN_ASM_MONT5 -DOPENSSL_BN_ASM_GF2m -DSHA1_ASM -DSHA256_ASM -DSHA512_ASM -DRC4_ASM -DMD5_ASM -DAES_ASM -DVPAES_ASM -DBSAES_ASM -DGHASH_ASM -DECP_NISTZ256_ASM -DPADLOCK_ASM -DPOLY1305_ASM -DOPENSSLDIR="\"/usr/local/ssl\"" -DENGINESDIR="\"/usr/local/lib/engines-1.1\"" -DDEBUG_UNUSED -Wswitch -DPEDANTIC -pedantic -Wno-long-long -Wall -Wsign-compare -Wmissing-prototypes -Wshadow -Wformat -Wtype-limits -Werror -Wa,--noexecstack The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes 16384 bytes lhash 147387.67k 147940.82k 144937.73k 147177.81k 147095.55k 147679.91k siphash 119939.99k 223694.38k 283383.30k 305372.84k 311760.21k 312120.66k So it seems that for short strings, OPENSSL_LH_strhash (*) wins some, while siphash wins big for larger strings. I have no idea how they compare with regard to distribution (which, considering I ask for the same size output from both, should be the main factor that affects the sensitivity to hash flooding)... Our use of OPENSSL_LH_strhash() is with configuration sections and names, ASN.1 object names and the function names in the openssl app. All our other uses of lhash use their own hashing functions, and are usually very short still (definitely less than 16 bytes). My conclusion is that performance-wise, siphash doesn't give us any advantage over OpenSSL_LH_strhash for our uses. Cheers, Richard (*) Strictly speaking, it's a modified version that takes a length and tolerates all 8-bit bytes, including 0x00. -- Richard Levitte levi...@openssl.org OpenSSL Project http://www.openssl.org/~levitte/ -- openssl-dev mailing list To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-dev
