| 1 | // Byte plumbing shared by the crypto modules. No key material logic here — |
| 2 | // just the conversions every other module would otherwise repeat. |
| 3 | |
| 4 | export const enc = new TextEncoder(); |
| 5 | export const dec = new TextDecoder(); |
| 6 | |
| 7 | export function toHex(b) { |
| 8 | return Array.from(b, (x) => x.toString(16).padStart(2, "0")).join(""); |
| 9 | } |
| 10 | |
| 11 | export function fromHex(s) { |
| 12 | if (s.length % 2) throw new Error("contra: odd-length hex"); |
| 13 | const out = new Uint8Array(s.length / 2); |
| 14 | for (let i = 0; i < out.length; i++) { |
| 15 | out[i] = parseInt(s.substr(i * 2, 2), 16); |
| 16 | } |
| 17 | return out; |
| 18 | } |
| 19 | |
| 20 | export function concat(...parts) { |
| 21 | let n = 0; |
| 22 | for (const p of parts) n += p.length; |
| 23 | const out = new Uint8Array(n); |
| 24 | let o = 0; |
| 25 | for (const p of parts) { |
| 26 | out.set(p, o); |
| 27 | o += p.length; |
| 28 | } |
| 29 | return out; |
| 30 | } |
| 31 | |
| 32 | export function u32be(n) { |
| 33 | return new Uint8Array([(n >>> 24) & 255, (n >>> 16) & 255, (n >>> 8) & 255, n & 255]); |
| 34 | } |
| 35 | |
| 36 | export function u32le(n) { |
| 37 | return new Uint8Array([n & 255, (n >>> 8) & 255, (n >>> 16) & 255, (n >>> 24) & 255]); |
| 38 | } |
| 39 | |
| 40 | // u64be takes a BigInt, because a version counter that silently loses |
| 41 | // precision above 2^53 would break the AAD binding in a way nothing would |
| 42 | // notice until a ciphertext failed to open. |
| 43 | export function u64be(n) { |
| 44 | const v = BigInt(n); |
| 45 | const out = new Uint8Array(8); |
| 46 | for (let i = 7; i >= 0; i--) out[i] = Number((v >> BigInt(8 * (7 - i))) & 0xffn); |
| 47 | return out; |
| 48 | } |
| 49 | |
| 50 | // equal is constant-time over the compared bytes. Length is not secret here |
| 51 | // — every field this compares is fixed-width — but the contents are. |
| 52 | export function equal(a, b) { |
| 53 | if (a.length !== b.length) return false; |
| 54 | let diff = 0; |
| 55 | for (let i = 0; i < a.length; i++) diff |= a[i] ^ b[i]; |
| 56 | return diff === 0; |
| 57 | } |
| 58 | |
| 59 | export function randomBytes(n) { |
| 60 | return crypto.getRandomValues(new Uint8Array(n)); |
| 61 | } |
| 62 | |
amadan