在circom中输入可变长度的字符串？

Question

我想表明用户知道 circom 中 sha256 哈希的原像。原像可以是任意长度，但实际上在 100-700 字节之间。我尝试了代码：

template ArbitraryLengthSha256 () {  
   signal input nBits;
   signal input preimage[nBits];  
   signal output result[256];  
   var i;
   component hashed = Sha256(nBits);
   for (i=0; i<nBits; i++) {
      hashed.in[i] <== preimage[i];
   }
   for (i=0; i<256; i++) {
      result[i] <== hashed.out[i];
   }
}

这会导致错误：

error[T20460]: Typing error found
  ┌─ "ppp.circom":8:26
  │
8 │    signal input preimage[nBits];  
  │                          ^^^^^ The length of every array must known during the constraint generation phase

error[T20461]: Typing error found
   ┌─ "ppp.circom":14:23
   │
14 │    component hashed = Sha256(nBits);
   │                       ^^^^^^^^^^^^^ Every component instantiation must be resolved during the constraint generation phase

error[T2005]: Typing error found
   ┌─ "ppp.circom":15:14
   │
15 │    for (i=0; i<nBits; i++) {
   │              ^^^^^^^ There are constraints depending on the value of the condition and it can be unknown during the constraint generation phase

有什么方法可以对 circom 中的任意长度字符串进行 sha256 哈希吗？

Answer 1

您可以 npm 安装此包：https://www.npmjs.com/package/@zk-email/ Circuits并导入此电路：https://github.com/zkemail/zk-email-verify/ blob/main/packages/ Circuits/helpers/sha256partial.circom 来做到这一点！