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koalaman edited this page Jan 21, 2018 · 1 revision

The shebang must be on the first line. Delete blanks and move comments.

Problematic code:

# Copyright 2018 Foobar, All rights reserved
#!/bin/bash

Correct code:

#!/bin/bash
# Copyright 2018 Foobar, All rights reserved

Rationale:

A shebang only has an effect when it appears as the first line in a script. Specifically, the first two bytes of the file must be #!.

Adding comments, copyright notices or simply an accidental blank line before it will turn a shebang into an ineffectual comment. This means that the script is no longer in charge of its own interpreter, and may fail to run or produce different results depending on the context it's run (e.g. it may work from bash but not from zsh or via sudo).

Delete any leading blank lines, and move all comments after the shebang.

Exceptions:

None

Related resources:

  • Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!
Add a custom footer

#!/usr/bin/env node “use strict”;

const crypto = require(“crypto”);

/* ================= Hash / Encoding ================= */

function sha256(b){ return crypto.createHash(“sha256”).update(b).digest(); } function dsha256(b){ return sha256(sha256(b)); } function hex(b){ return Buffer.from(b).toString(“hex”); }

function b64u(b){

return Buffer.from(b).toString("base64")
  .replace(/\+/g,"-").replace(/\//g,"_").replace(/=+$/,"");

}

function b64uDec(s){

const p=s.replace(/-/g,"+").replace(/_/g,"/")+"===".slice((s.length+3)%4);
return Buffer.from(p,"base64");

}

/* ================= STDIN ================= */

async function readStdin(){

return new Promise(res=>{
  const chunks=[];
  process.stdin.on("data",c=>chunks.push(c));
  process.stdin.on("end",()=>res(Buffer.concat(chunks)));
  if(process.stdin.isTTY) res(Buffer.alloc(0));
});

}

/* ================= Ints ================= */

function u32le(n){ const b=Buffer.alloc(4); b.writeUInt32LE(n>>>0,0); return b; } function u32be(n){ const b=Buffer.alloc(4); b.writeUInt32BE(n>>>0,0); return b; }

function u64le(n){

const b=Buffer.alloc(8);
let x=BigInt(n);
for(let i=0;i<8;i++){ b[i]=Number(x&0xffn); x>>=8n; }
return b;

}

function varint(n){

if(n<0xfd) return Buffer.from([n]);
const b=Buffer.alloc(3);
b[0]=0xfd;
b.writeUInt16LE(n,1);
return b;

}

/* ================= PoW ================= */

function bitsToTarget(bits){

const exp=(bits>>>24)&0xff;
const mant=BigInt(bits & 0x1d00ffff);
if(exp<=3) return mant >> BigInt(8*(3-exp));
return mant << BigInt(8*(exp-3));

}

function hashToBigIntLE(h){

return BigInt("0x"+hex(Buffer.from(h).reverse()));

}

/* ================= Merkle ================= */

function merkleParent(a,b){ return dsha256(Buffer.concat([a,b])); }

function merkleRoot(leaves){

let level=leaves.slice();
while(level.length>1){
  const next=[];
  for(let i=0;i<level.length;i+=2){
    const L=level[i];
    const R=(i+1<level.length)?level[i+1]:level[i];
    next.push(merkleParent(L,R));
  }
  level=next;
}
return level[0];

}

function merkleAuthPath(leaves,index){

let idx=index;
let level=leaves.slice();
const path=[];
while(level.length>1){
  const sib=idx^1;
  path.push((sib<level.length)?level[sib]:level[idx]);

  const next=[];
  for(let i=0;i<level.length;i+=2){
    const L=level[i];
    const R=(i+1<level.length)?level[i+1]:level[i];
    next.push(merkleParent(L,R));
  }

  level=next;
  idx=Math.floor(idx/2);
}
return path;

}

function recomputeRootFromPath(leaf,index,path){

let node=Buffer.from(leaf);
let idx=index;
for(const sib of path){
  node=(idx&1) ? merkleParent(sib,node) : merkleParent(node,sib);
  idx=Math.floor(idx/2);
}
return node;

}

/* ================= WOTS ================= */

const WOTS_N=32; const WOTS_W=16; const WOTS_LEN1=64; const WOTS_LEN2=3; const WOTS_LEN=67;

function wotsF(x){

return sha256(Buffer.concat([Buffer.from("WOTSF"),x]));

}

function wotsChain(x,steps){

let y=Buffer.from(x);
for(let i=0;i<steps;i++) y=wotsF(y);
return y;

}

function wotsSkElem(seed,leaf,i){

return sha256(Buffer.concat([
  Buffer.from("WOTSSK"),
  seed,
  u32be(leaf),
  u32be(i)
]));

}

function baseW(digest){

const out=[];
for(let i=0;i<32;i++){
  out.push((digest[i]>>>4)&15);
  out.push(digest[i]&15);
}
return out;

}

function checksumDigits(digits){

let c=0;
for(const d of digits) c+=15-d;

const out=[0,0,0];
for(let i=2;i>=0;i--){
  out[i]=c%16;
  c=Math.floor(c/16);
}
return out;

}

function wotsDigits(digest){

const d=baseW(digest);
return d.concat(checksumDigits(d));

}

function wotsPublicKeyHash(seed,leaf){

const parts=[];
for(let i=0;i<WOTS_LEN;i++){
  const sk=wotsSkElem(seed,leaf,i);
  parts.push(wotsChain(sk,15));
}
return sha256(Buffer.concat([Buffer.from("WOTSPK"),...parts]));

}

function wotsSign(seed,leaf,msg){

const digest=sha256(msg);
const digits=wotsDigits(digest);
const sig=Buffer.alloc(WOTS_LEN*WOTS_N);

for(let i=0;i<WOTS_LEN;i++){
  const sk=wotsSkElem(seed,leaf,i);
  const si=wotsChain(sk,digits[i]);
  si.copy(sig,i*WOTS_N);
}

return {digest,sig};

}

/* ================= ECDSA Hybrid ================= */

function makeEcdsa(){

const kp=crypto.generateKeyPairSync("ec",{namedCurve:"secp256k1"});
const pubDer=kp.publicKey.export({type:"spki",format:"der"});
return {privateKey:kp.privateKey, publicKey:kp.publicKey, pubDer};

}

function ecdsaMessage(stdinHash,pqRoot,pqSigHash){

return dsha256(Buffer.concat([
  Buffer.from("ECDSA-SIGN|PQH2|"),
  stdinHash,
  pqRoot,
  pqSigHash
]));

}

function signEcdsa(priv,msg){

return crypto.sign(null,msg,priv);

}

function verifyEcdsa(pubDer,msg,sig){

const pub=crypto.createPublicKey({key:pubDer,type:"spki",format:"der"});
return crypto.verify(null,msg,pub,sig);

}

function hybridHash(pqRoot,pqSigHash,ecdsaPubHash,ecdsaSigHash){

return dsha256(Buffer.concat([
  Buffer.from("HYBRID|PQH2|"),
  pqRoot,
  pqSigHash,
  ecdsaPubHash,
  ecdsaSigHash
]));

}

/* ================= Bitcoin Scripts ================= */

function scriptP2PKH(h160){

return Buffer.concat([
  Buffer.from([0x76,0xa9,0x14]),
  h160,
  Buffer.from([0x88,0xac])
]);

}

function scriptOpReturnHybrid(hybrid){

const payload=Buffer.concat([Buffer.from("PQH2"),hybrid]);
return Buffer.concat([Buffer.from([0x6a,0x24]),payload]);

}

/* ================= TX / Block ================= */

function buildCoinbaseTx({bits,msg,opret,reward,p2pkh}){

const prev=Buffer.alloc(32,0);
const vout=Buffer.from("ffffffff","hex");
const seq=Buffer.from("ffffffff","hex");
const bitsLE=u32le(bits);
const msgBuf=Buffer.from(msg,"utf8");

const scriptSig=Buffer.concat([
  Buffer.from([4]),bitsLE,
  varint(msgBuf.length),msgBuf
]);

const vin=Buffer.concat([
  prev,
  vout,
  varint(scriptSig.length),
  scriptSig,
  seq
]);

const out0=Buffer.concat([u64le(0n),varint(opret.length),opret]);
const out1=Buffer.concat([u64le(reward),varint(p2pkh.length),p2pkh]);

const tx=Buffer.concat([
  u32le(1),
  Buffer.from([1]),vin,
  Buffer.from([2]),out0,out1,
  u32le(0)
]);

return {
  tx,
  txidInternal:dsha256(tx),
  txidDisplay:Buffer.from(dsha256(tx)).reverse()
};

}

function mineHeader({merkle,time,bits}){

const target=bitsToTarget(bits);
let nonce=0;

while(true){
  const header=Buffer.concat([
    u32le(2),
    Buffer.alloc(32,0),
    merkle,
    u32le(time),
    u32le(bits),
    u32le(nonce)
  ]);

  const h=dsha256(header);
  if(hashToBigIntLE(h)<=target){
    return {nonce,header,hash:h,display:Buffer.from(h).reverse()};
  }

  nonce=(nonce+1)>>>0;
  if(nonce===0) throw new Error("nonce wrapped");
}

}

/* ================= Verify ================= */

function verifyRecord(j){

const sigBlob=b64uDec(j.pq.signature_compressed_b64u);

const tag=sigBlob.slice(0,4).toString();
const leaf=sigBlob.readUInt32BE(4);
const leafPk=sigBlob.slice(8,40);
const digest=sigBlob.slice(40,72);
const wotsSig=sigBlob.slice(72,72+(WOTS_LEN*WOTS_N));
const auth=sigBlob.slice(72+(WOTS_LEN*WOTS_N));

const authNodes=[];
for(let i=0;i<auth.length;i+=32) authNodes.push(auth.slice(i,i+32));

const sigHash=dsha256(sigBlob);
const pqRoot=recomputeRootFromPath(leafPk,leaf,authNodes);

const pubDer=b64uDec(j.hybrid.ecdsa_pubkey_spki_der_b64u);
const ecdsaSig=b64uDec(j.hybrid.ecdsa_signature_der_b64u);
const stdinHash=Buffer.from(j.stdin.dsha256_hex,"hex");
const ecdsaMsg=ecdsaMessage(stdinHash,pqRoot,sigHash);
const ecdsaValid=verifyEcdsa(pubDer,ecdsaMsg,ecdsaSig);

const ecdsaPubHash=dsha256(Buffer.concat([Buffer.from("ECDSA-PUB|PQH2|"),pubDer]));
const ecdsaSigHash=dsha256(ecdsaSig);
const hybrid=hybridHash(pqRoot,sigHash,ecdsaPubHash,ecdsaSigHash);

const opret=Buffer.from(j.bitcoin.op_return_scriptpubkey_hex,"hex");
const opHybrid=opret.slice(6,38);

const tx=Buffer.from(j.bitcoin.coinbase_tx_hex,"hex");
const txid=Buffer.from(dsha256(tx)).reverse();

const header=Buffer.from(j.bitcoin.header_hex,"hex");
const blockHash=Buffer.from(dsha256(header)).reverse();

const bits=parseInt(j.bitcoin.bits_hex,16);
const powOk=hashToBigIntLE(dsha256(header))<=bitsToTarget(bits);

return {
  verify:true,
  signature_tag_ok:tag==="PQSW",
  leaf_index_matches:leaf===j.pq.leaf_index,
  signature_hash_matches:hex(sigHash)===j.pq.sig_hash_dsha256_hex,
  pq_root_matches:hex(pqRoot)===j.pq.pq_root_hex,
  ecdsa_signature_valid:ecdsaValid,
  ecdsa_pubkey_hash_matches:hex(ecdsaPubHash)===j.hybrid.ecdsa_pubkey_hash_dsha256_hex,
  ecdsa_signature_hash_matches:hex(ecdsaSigHash)===j.hybrid.ecdsa_signature_hash_dsha256_hex,
  hybrid_hash_matches:hex(hybrid)===j.hybrid.hybrid_hash_dsha256_hex,
  op_return_hybrid_matches:hex(opHybrid)===j.hybrid.hybrid_hash_dsha256_hex,
  txid_matches:hex(txid)===j.bitcoin.coinbase_txid,
  block_hash_matches:hex(blockHash)===j.bitcoin.block_hash,
  proof_of_work_valid:powOk
};

}

/* ================= Build ================= */

function build(stdin){

const stdinHash=dsha256(Buffer.concat([Buffer.from("STDIN|PQ|"),stdin]));
const seed=stdinHash;

const height=4;
const leafCount=1<<height;
const leafIndex=stdinHash[0]%leafCount;

const leaves=[];
for(let i=0;i<leafCount;i++) leaves.push(wotsPublicKeyHash(seed,i));

const pqRoot=merkleRoot(leaves);
const auth=merkleAuthPath(leaves,leafIndex);
const authBuf=Buffer.concat(auth);

const pqMsg=sha256(Buffer.concat([
  Buffer.from("PQGEN|"),
  stdinHash,
  Buffer.from("|"),
  pqRoot
]));

const signed=wotsSign(seed,leafIndex,pqMsg);
const leafPk=leaves[leafIndex];

const sigBlob=Buffer.concat([
  Buffer.from("PQSW"),
  u32be(leafIndex),
  leafPk,
  signed.digest,
  signed.sig,
  authBuf
]);

const pqSigHash=dsha256(sigBlob);

const ecdsa=makeEcdsa();
const ecdsaMsg=ecdsaMessage(stdinHash,pqRoot,pqSigHash);
const ecdsaSig=signEcdsa(ecdsa.privateKey,ecdsaMsg);

const ecdsaPubHash=dsha256(Buffer.concat([
  Buffer.from("ECDSA-PUB|PQH2|"),
  ecdsa.pubDer
]));

const ecdsaSigHash=dsha256(ecdsaSig);
const hybrid=hybridHash(pqRoot,pqSigHash,ecdsaPubHash,ecdsaSigHash);
const opret=scriptOpReturnHybrid(hybrid);

const p2pkhHash=sha256(Buffer.concat([Buffer.from("P2PKH|"),stdin])).subarray(0,20);
const p2pkh=scriptP2PKH(p2pkhHash);

const bits=0x1d00ffff;
const time=(Math.floor(Date.now()/1000))>>>0;
const reward=5000000000n;

const tx=buildCoinbaseTx({
  bits,
  msg:`PQ-HYBRID|${new Date(time*1000).toISOString()}`,
  opret,
  reward,
  p2pkh
});

const mined=mineHeader({merkle:tx.txidInternal,time,bits});
const block=Buffer.concat([mined.header,Buffer.from([1]),tx.tx]);

return {
  schema:"pq_genesis_block_stdin/hybrid-wots-ecdsa-v1",
  stdin:{
    bytes:stdin.length,
    dsha256_hex:hex(stdinHash)
  },
  pq:{
    scheme:"wots-sha256-merkle",
    params:{n:32,w:16,len:67,len1:64,len2:3,height},
    leaf_index:leafIndex,
    pq_root_hex:hex(pqRoot),
    message_sha256_hex:hex(pqMsg),
    wots_digest_hex:hex(signed.digest),
    signature_len_bytes:sigBlob.length,
    signature_compressed_b64u:b64u(sigBlob),
    sig_hash_dsha256_hex:hex(pqSigHash),
    auth_path_hex:auth.map(hex)
  },
  hybrid:{
    scheme:"ecdsa-secp256k1+wots-sha256-merkle",
    op_return_version:"PQH2",
    ecdsa_pubkey_spki_der_b64u:b64u(ecdsa.pubDer),
    ecdsa_pubkey_hash_dsha256_hex:hex(ecdsaPubHash),
    ecdsa_signature_der_b64u:b64u(ecdsaSig),
    ecdsa_signature_hash_dsha256_hex:hex(ecdsaSigHash),
    hybrid_hash_dsha256_hex:hex(hybrid)
  },
  bitcoin:{
    bits_hex:bits.toString(16),
    time_unix:time,
    op_return_scriptpubkey_hex:hex(opret),
    coinbase_tx_hex:hex(tx.tx),
    coinbase_txid:hex(tx.txidDisplay),
    merkle_root_display:hex(tx.txidDisplay),
    header_hex:hex(mined.header),
    block_hash:hex(mined.display),
    nonce:mined.nonce,
    full_block_hex:hex(block),
    full_block_bytes:block.length
  }
};

}

/* ================= Main ================= */

(async()=>{

const input=await readStdin();
if(input.length===0) throw new Error("No STDIN");

let json=null;
try{ json=JSON.parse(input.toString()); }catch{}

if(json && json.schema){
  console.log(JSON.stringify(verifyRecord(json),null,2));
}else{
  console.log(JSON.stringify(build(input),null,2));
}

})();

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