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joplin/packages/app-mobile/services/e2ee/RSA.react-native.ts
2024-08-02 14:51:49 +01:00

95 lines
3.2 KiB
TypeScript

import { RSA } from '@joplin/lib/services/e2ee/types';
import shim from '@joplin/lib/shim';
import Logger from '@joplin/utils/Logger';
const RnRSA = require('react-native-rsa-native').RSA;
interface RSAKeyPair {
public: string;
private: string;
keySizeBits: number;
}
const logger = Logger.create('RSA');
const rsa: RSA = {
generateKeyPair: async (keySize: number): Promise<RSAKeyPair> => {
if (shim.mobilePlatform() === 'web') {
// TODO: Try to implement with SubtleCrypto. May require migrating the RSA algorithm used on
// desktop and mobile (which is not supported on web). See commit 12adcd9dbc3f723bac36ff4447701573084c4694.
logger.warn('RSA on web is not yet supported.');
return null;
}
const keys: RSAKeyPair = await RnRSA.generateKeys(keySize);
// Sanity check
if (!keys.private) throw new Error('No private key was generated');
if (!keys.public) throw new Error('No public key was generated');
return rsa.loadKeys(keys.public, keys.private, keySize);
},
loadKeys: async (publicKey: string, privateKey: string, keySizeBits: number): Promise<RSAKeyPair> => {
return { public: publicKey, private: privateKey, keySizeBits };
},
encrypt: async (plaintextUtf8: string, rsaKeyPair: RSAKeyPair): Promise<string> => {
// TODO: Support long-data encryption in a way compatible with node-rsa.
return RnRSA.encrypt(plaintextUtf8, rsaKeyPair.public);
},
decrypt: async (ciphertextBase64: string, rsaKeyPair: RSAKeyPair): Promise<string> => {
const ciphertextBuffer = Buffer.from(ciphertextBase64, 'base64');
const maximumEncryptedSize = Math.floor(rsaKeyPair.keySizeBits / 8); // Usually 256
// On iOS, .decrypt fails without throwing or rejecting.
// This function throws for consistency with Android.
const handleError = (plainText: string|undefined) => {
if (plainText === undefined) {
throw new Error(`
RN RSA: Decryption failed.
cipherTextLength=${ciphertextBuffer.length},
maxEncryptedSize=${maximumEncryptedSize}
`.trim());
}
};
// Master keys are encrypted with RSA and are longer than the default modulus size of 256 bytes.
// node-rsa supports encrypting larger amounts of data using RSA.
// See their implementation for details: https://github.com/rzcoder/node-rsa/blob/e7e7f7d2942a3bac1d2e132a881e5a3aceda10a1/src/libs/rsa.js#L252
if (ciphertextBuffer.length > maximumEncryptedSize) {
// Use a numBlocks and blockSize that match node-rsa:
const numBlocks = Math.ceil(ciphertextBuffer.length / maximumEncryptedSize);
const blockSize = maximumEncryptedSize;
const result: string[] = [];
for (let i = 0; i < numBlocks; i++) {
const ciphertextBlock = ciphertextBuffer.slice(
i * blockSize, Math.min(ciphertextBuffer.length, (i + 1) * blockSize),
);
const plainText = await RnRSA.decrypt(ciphertextBlock.toString('base64'), rsaKeyPair.private);
handleError(plainText);
result.push(plainText);
}
return result.join('');
} else {
const plainText = await RnRSA.decrypt(ciphertextBase64, rsaKeyPair.private);
handleError(plainText);
return plainText;
}
},
publicKey: (rsaKeyPair: RSAKeyPair): string => {
return rsaKeyPair.public;
},
privateKey: (rsaKeyPair: RSAKeyPair): string => {
return rsaKeyPair.private;
},
};
export default rsa;