SubtleCrypto

`crypto.subtle.decrypt`

Decrypts encrypted data using the specified algorithm and cryptographic key

Syntax

JavaScript

crypto.subtle.decrypt(algorithm, key, data)

Parameters

Parameter	Type	Description
algorithm	AlgorithmIdentifier	The decryption algorithm and parameters
key	CryptoKey	The key to use for decryption
data	ArrayBuffer \| TypedArray \| DataView	The data to decrypt

Return Value

A Promise that resolves to an ArrayBuffer containing the plaintext

Examples

Basic Usage

const decrypted = await crypto.subtle.decrypt(
  { name: 'AES-GCM', iv },
  key,
  encryptedData
)
const text = new TextDecoder().decode(decrypted)
console.log(text) // 'Secret message'

Practical Example

async function decryptText(cipher: ArrayBuffer, iv: Uint8Array, key: CryptoKey) {
  const decrypted = await crypto.subtle.decrypt(
    { name: 'AES-GCM', iv },
    key,
    cipher
  )
  return new TextDecoder().decode(decrypted)
}

Advanced Usage

async function decryptMessage(encrypted: ArrayBuffer, key: CryptoKey, iv: Uint8Array) {
  try {
    const plain = await crypto.subtle.decrypt({ name: 'AES-GCM', iv }, key, encrypted)
    return new TextDecoder().decode(plain)
  } catch {
    throw new Error('Decryption failed — wrong key or corrupted data')
  }
}

Understanding crypto.subtle.decrypt

The crypto.subtle.decrypt method in JavaScript decrypts encrypted data using the specified algorithm and cryptographic key. It belongs to the SubtleCrypto object and is one of the most widely used methods for working with subtlecrypto values in modern JavaScript and TypeScript applications.

The method signature is crypto.subtle.decrypt(algorithm, key, data). It accepts 3 parameters: algorithm, key, data. When called, it returns a promise that resolves to an arraybuffer containing the plaintext. Understanding when and how to use decrypt() helps you write more expressive, readable code.

Common use cases for crypto.subtle.decrypt include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like crypto-subtle-encrypt, crypto-subtle-digest, crypto-getrandomvalues, enabling you to chain operations together for complex data manipulation pipelines.

Supported in all modern browsers. Requires a secure context (HTTPS).