openssl - Is the truncated to 64 bit sha1 of a 64 bit number guarenteed to be unique? -

openssl - Is the truncated to 64 bit sha1 of a 64 bit number guarenteed to be unique? -

i'm not crypto expert, or trying cryptography, need decorrelate 64 bit hash (for simhash algorithm, in case cares). if take lowest 64 bits of sha1 has on 64 bit key (8 bytes), result guaranteed unique? "close plenty unique", i'd know sure.

(to reply "what i've tried", i've run loop upper 32 sectiion iterating 0 10000, , lower 32 bit doing same without hits.)

per raymond chen, reply no

openssl sha1