algorithm - Locking data for x days -

is there (easy) way encrypt data takes amount of cpu hours decrypt it? maybe series of encryptions short key lengths, variable one-way function or anything?

it's not of great use, how encryption scheme called , there tools it?

edit:

to no varying results brute force break time, shouldn't use many rounds xor-feedback?

i came algo (for symmetric block cipher equal value , key length)... maybe it's non-sense

 round 1  create zero-block create random-block-1 encipher value:zero-block key:random-block1    => gives lock-output-1  round 2  create zero-block create random-block-2 encipher value:zero-block key:random-block2    => gives temp xor temp random-block-1                        => gives lock-output-2  , on 

the xor operation random-block-1 there unlock routine have find random-block-1 before can start brute forcing on lock-output-2.

lock-output-1 + lock-output-2 .. lock-output-n complete lock-output. when unlock routine has found n key-blocks each give 0 on lock-output blocks, can use n key-blocks whole decipher actual data.

then i'd need formula calculate how many rounds give maximum variation of e.g. 10% wanted amount of cpu hours.

i guess there must exist simmilar algorithm out there.

the concept called timed commitment, defined boneh , naor. data want encrypt said committed 1 party (which call sender), such party (the receiver) may, @ tunable cost, recover data.

the method described boneh , naor quite more advanced suggest. timed commitment scheme has 3 following properties:

• verifiable recovery: sender able convince receiver did commit proper value receiver will able recover applying substantial feasible amount of cpu muscle it.

• recovery proof: once recovery has been done, verifiable efficiently: third party wishing verify recovered value indeed 1 committed, can efficiently (without applying hours of cpu it).

• immunity against parallel attacks: recovery process cannot benefit having access thousand pc: 1 cannot go faster can done single cpu.

with these properties, timed commitment becomes worthwhile tool in situations; boneh , naor discuss contract signing, honesty preserving auctions , few other applications.

i not aware of actual implementation or defined protocol timed commitments, beyond mathematical description boneh , naor.