Created
November 8, 2022 15:02
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AES CBC sample(execute it on chrome console to see the result)
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| (async () => { | |
| /* | |
| Get the encoded message, encrypt it and display a representation | |
| of the ciphertext in the "Ciphertext" element. | |
| */ | |
| async function encrypt(key, plainText, iv) { | |
| let encoded = new TextEncoder().encode(plainText); | |
| const ciphertext = await window.crypto.subtle.encrypt( | |
| { | |
| name: "AES-CBC", | |
| iv | |
| }, | |
| key, | |
| encoded | |
| ); | |
| return ciphertext; | |
| } | |
| /* | |
| Fetch the ciphertext and decrypt it. | |
| Write the decrypted message into the "Decrypted" box. | |
| */ | |
| async function decrypt(key, ciphertext, iv) { | |
| const decrypted = await window.crypto.subtle.decrypt( | |
| { | |
| name: "AES-CBC", | |
| iv | |
| }, | |
| key, | |
| ciphertext | |
| ); | |
| return new TextDecoder().decode(decrypted); | |
| } | |
| // Uint8Array[122, 239, 98, 195, 223, 136, 255, 37, 210, 243, 97, 246, 54, 100, 114, 11] -> '122,239,98,195,223,136,255,37,210,243,97,246,54,100,114,11' | |
| const uint8ArrayToStr = iv => iv.toString(); | |
| // '122,239,98,195,223,136,255,37,210,243,97,246,54,100,114,11' -> Uint8Array[122, 239, 98, 195, 223, 136, 255, 37, 210, 243, 97, 246, 54, 100, 114, 11] | |
| const strToUint8Array = str => Uint8Array.from(str.split(',').map(e => parseInt(e))); | |
| /* | |
| Store the calculated ciphertext and IV here, so we can decrypt the message later. | |
| */ | |
| let iv = window.crypto.getRandomValues(new Uint8Array(16)); // The iv must never be reused with a given key. | |
| let key = await window.crypto.subtle.generateKey( | |
| { | |
| name: "AES-CBC", | |
| length: 256 | |
| }, | |
| true, | |
| ["encrypt", "decrypt"] | |
| ); | |
| let keyArrayBuffer = await crypto.subtle.exportKey('raw', key); | |
| let keyStr = new Uint8Array(keyArrayBuffer).toString(); | |
| console.log(`key to be kept secret: ${keyStr}`); | |
| let plaintext = 'Hello world!'; | |
| let ciphertext = await encrypt(key, plaintext, iv); | |
| let ciphertextStr = new Uint8Array(ciphertext).toString(); | |
| let ivStr=uint8ArrayToStr(iv); | |
| console.log(`For public transfer, encoded data: ${ciphertextStr},\niv: ${ivStr}`); | |
| // ------ decrypt with the information above | |
| // restore ciphertext bytes from ciphertext string | |
| let ciphertext2 = strToUint8Array(ciphertextStr); | |
| // restore key bytes from key string | |
| let keyArrayBuffer2 = strToUint8Array(keyStr); | |
| let key2 = await crypto.subtle.importKey( | |
| "raw", | |
| keyArrayBuffer2.buffer, | |
| "AES-CBC", | |
| false, | |
| ["encrypt", "decrypt"] | |
| ); | |
| // restore iv bytes from iv string | |
| let iv2=strToUint8Array(ivStr); | |
| let decText = await decrypt(key2, ciphertext2, iv2); | |
| console.log(decText); | |
| })(); | |
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