Question

我正在尝试使用SubtleCrypto在javascript（firefox）中加密字符串。问题是，加密仅适用于短输入。一旦字符串（testdata）超过190个字符，它将失败并出现OperationError。为什么SubtleCrypto的表现如此，我该如何解决呢？

代码：

function str2ab(str) {
  var encoder = new TextEncoder('utf-8');
  return encoder.encode(str);
}

function ab2str(buf) {
  var decoder = new TextDecoder('utf-8');
  return decoder.decode(buf);
}

var keypair;
var algorithmKeyGen = {
  name: 'RSA-OAEP',
  modulusLength: 2048,
  publicExponent: new Uint8Array([1,
    0,
    1
  ]), // Equivalent to 65537
  hash: {
    name: 'SHA-256'
  }
};
var crypter = window.crypto.subtle;

function encrypt(buffer) {
  return crypter.encrypt(algorithmKeyGen, keypair.publicKey, buffer).then(
    function(data) {
      alert(ab2str(data));
    },
    function(error) {
      alert(error);
    }
  );
}

var testdata = "aasasadasdaasasadasdaasazzzzzzzzzzzzzzzzzzzzuuuuuuuuuuuuuuuuuuuuuuuzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzuuuuudddsdfssssssssssdddddddddddzzzzzzzzzzzzzzzzzzzzzzzzzzzzzppppppggppppppppppppppppssssstt"

crypter.generateKey(algorithmKeyGen, true, [
  'sign',
  'encrypt',
  'decrypt',
  'verify',
  'deriveKey'
]).then(function(res) {
  keypair = res;
  encrypt(str2ab(testdata));
}, console.error.bind(console, 'Unable to generate a key'));