Press n or j to go to the next uncovered block, b, p or k for the previous block.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 | 1x 1x 1x 12x 12x | import randomBytes from 'randombytes'; import type { IDecryptionModeOfOperation, IEncryptionModeOfOperation, IModeOfOperation } from './IModeOfOperation'; import { xor } from '../../utils/xor'; export class CTRMode implements IModeOfOperation { public readonly encryption = new CTRMode.CTREncryptionMode(); public readonly decryption = new CTRMode.CTRDecryptionMode(); } // istanbul ignore next export namespace CTRMode { export function incrementCounter(counter: Uint8Array): void { for (let i = 15; i >= 0; i--) { if (counter[i] !== 255) { counter[i] += 1; break; } else { counter[i] = 0; if (i === 0) counter[15] = 0; } } } export class CTREncryptionMode implements IEncryptionModeOfOperation { private counter: Uint8Array | null = null; public start(): Uint8Array { this.counter = randomBytes(16); return new Uint8Array(this.counter); } public combine(block: Uint8Array, encrypt: (block: Uint8Array) => Uint8Array): Uint8Array { if (this.counter === null) throw new Error('CTR encryption mode not started.'); incrementCounter(this.counter); return xor(this.counter, encrypt(block)); } public finish(): Uint8Array { this.counter = null; return new Uint8Array(); } } export class CTRDecryptionMode implements IDecryptionModeOfOperation { private counter: Uint8Array | null = null; public start(): Uint8Array { this.counter = null; return new Uint8Array(); } public combine(block: Uint8Array, decrypt: (block: Uint8Array) => Uint8Array): Uint8Array { if (this.counter === null) { this.counter = new Uint8Array(block); return new Uint8Array(); } incrementCounter(this.counter); const decrypted = decrypt(xor(this.counter, block)); return decrypted; } public finish(): Uint8Array { this.counter = null; return new Uint8Array(); } } } |