library HashLadder{
    
    function genPubKey(bytes32[2][32] privKey) returns (bytes32[2][32]){
        bytes32[2][32] memory pubKey;
        for(uint8 i; i< 32; i++){
            bytes32 pa = privKey[i][0];        
            bytes32 pb = privKey[i][1];
            for(uint k; k<258; k++){
                pa = sha3(pa);
                pb = sha3(pb);
            }
            pubKey[i] = [pa,pb];
        }
        return pubKey;
    }
    
    function sign_chunk(byte chunk, bytes32[2] privKey) constant returns(bytes32[2]){
        bytes32[2] memory pubKey;
        uint n = uint8(chunk);
        bytes32 a = privKey[0];
        bytes32 b = privKey[1];
        

        for(uint i; i < n+1; i++){
            a = sha3(a);
        }
        for(uint j; j < 256-n; j++){
            b = sha3(b);
        }
        
        return([a,b]);
        
    }
    
    function sign(bytes message, bytes32[2][32] privKey) returns(bytes32[2][32]){
        bytes32 hash = sha3(message);
        bytes32[2][32] memory sig;
        bytes32[2][32] memory key;
        for(uint8 i; i<32;i++){
            sig[i] = sign_chunk(hash[i],privKey[i]);
        }
        return (sig);
    }
    
    
    function verify_chunk(byte chunk, bytes32[2] pubKey, bytes32[2] signature) constant returns (bool){
        uint a_i;
        uint b_i;
        bytes32 a = signature[0];
        bytes32 b = signature[1];
        while(b_i <= 258 && b != pubKey[1]){
            b = sha3(b);
            b_i++;
        }
        
        while(a_i <= 258 && a != pubKey[0]){
            a = sha3(a);
            a_i++;
        }
        
        
        return (uint(chunk) == b_i - 2 && b_i == 259 - a_i);
        //return true;
    }
    
    
    function verify(bytes32 msgHash, bytes32[2][32] pubKey, bytes32[2][32] signature) public returns (bool){
        for(uint8 i; i<32; i++){
            if(!verify_chunk(msgHash[i],pubKey[i],signature[i])) return false;
        }
        return true;
    }
    
}