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refactor(base64): up to 500% performance increase

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This commit is contained in:
Simon Chan 2020-09-25 14:47:40 +08:00
parent 544cc8d0e4
commit 16dc23c6b5
4 changed files with 242 additions and 53 deletions
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55
packages/adb/src/crypto.ts
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@ -113,7 +113,23 @@ export function modInverse(a: number, m: number) {
return (y % m + m) % m;
}
export function calculatePublicKey(privateKey: ArrayBuffer): ArrayBuffer {
export function calculatePublicKeyLength() {
return 4 + 4 + 2048 / 8 + 2048 / 8 + 4;
}
export function calculatePublicKey(
privateKey: ArrayBuffer
): ArrayBuffer;
export function calculatePublicKey(
privateKey: ArrayBuffer,
output: ArrayBuffer,
outputOffset?: number
): number;
export function calculatePublicKey(
privateKey: ArrayBuffer,
output?: ArrayBuffer,
outputOffset: number = 0
): ArrayBuffer | number {
// Android has its own public key generation algorithm
// See https://github.com/aosp-mirror/platform_system_core/blob/e5c9bbd45381d7bd72fef232d1c6668946253ac8/libcrypto_utils/android_pubkey.cpp#L111
@ -134,29 +150,50 @@ export function calculatePublicKey(privateKey: ArrayBuffer): ArrayBuffer {
// extract `n` from private key
const [n] = parsePrivateKey(privateKey);
const publicKey = new ArrayBuffer(4 + 4 + 2048 / 8 + 2048 / 8 + 4);
const publicKeyView = new DataView(publicKey);
let outputType: 'ArrayBuffer' | 'number';
const outputLength = calculatePublicKeyLength();
if (!output) {
output = new ArrayBuffer(outputLength);
outputType = 'ArrayBuffer';
} else {
if (output.byteLength - outputOffset < outputLength) {
throw new Error('output buffer is too small');
}
outputType = 'number';
}
const outputView = new DataView(output);
// modulusLengthInWords
publicKeyView.setUint32(0, 2048 / 8 / 4, true);
outputView.setUint32(outputOffset, 2048 / 8 / 4, true);
outputOffset += 4;
// Calculate `n0inv`
// Don't know why need to multiple -1
// Didn't exist in Android codebase
const n0inv = modInverse(Number(BigInt.asUintN(32, n) * BigInt(-1)), 2 ** 32);
publicKeyView.setUint32(4, n0inv, true);
outputView.setUint32(outputOffset, n0inv, true);
outputOffset += 4;
// Write n
setBigLE(publicKey, n, 8);
setBigLE(output, n, outputOffset);
outputOffset += 256;
// Calculate rr = (2^(rsa_size)) ^ 2 mod n
let rr = BigInt(2) ** BigInt(4096) % n;
setBigLE(publicKey, rr, 8 + 256);
setBigLE(output, rr, outputOffset);
outputOffset += 256;
// exponent
publicKeyView.setUint32(8 + 256 + 256, 65537, true);
outputView.setUint32(outputOffset, 65537, true);
outputOffset += 4;
return publicKey;
if (outputType === 'ArrayBuffer') {
return output;
} else {
return outputLength;
}
}
// Modular exponentiation