52 lines · 1.5 KB
| 1 | /** |
| 2 | * SHA-1 hashing using the Web Crypto API. |
| 3 | * Used for computing git object IDs. |
| 4 | */ |
| 5 | |
| 6 | const encoder = new TextEncoder(); |
| 7 | |
| 8 | /** Compute SHA-1 hash of data, returning a 40-character hex string. */ |
| 9 | export async function sha1(data: Uint8Array): Promise<string> { |
| 10 | const hashBuffer = await crypto.subtle.digest('SHA-1', data); |
| 11 | return hexEncode(new Uint8Array(hashBuffer)); |
| 12 | } |
| 13 | |
| 14 | /** Compute SHA-256 hash of data, returning a 64-character hex string. */ |
| 15 | export async function sha256(data: Uint8Array): Promise<string> { |
| 16 | const hashBuffer = await crypto.subtle.digest('SHA-256', data); |
| 17 | return hexEncode(new Uint8Array(hashBuffer)); |
| 18 | } |
| 19 | |
| 20 | /** Encode a Uint8Array as a hex string. */ |
| 21 | export function hexEncode(bytes: Uint8Array): string { |
| 22 | let hex = ''; |
| 23 | for (let i = 0; i < bytes.length; i++) { |
| 24 | hex += bytes[i].toString(16).padStart(2, '0'); |
| 25 | } |
| 26 | return hex; |
| 27 | } |
| 28 | |
| 29 | /** Decode a hex string to Uint8Array. */ |
| 30 | export function hexDecode(hex: string): Uint8Array { |
| 31 | const bytes = new Uint8Array(hex.length / 2); |
| 32 | for (let i = 0; i < hex.length; i += 2) { |
| 33 | bytes[i / 2] = parseInt(hex.substring(i, i + 2), 16); |
| 34 | } |
| 35 | return bytes; |
| 36 | } |
| 37 | |
| 38 | /** |
| 39 | * Compute the SHA-1 hash of a git object. |
| 40 | * Git objects are hashed as: "{type} {size}\0{content}" |
| 41 | */ |
| 42 | export async function gitObjectHash( |
| 43 | type: string, |
| 44 | content: Uint8Array |
| 45 | ): Promise<string> { |
| 46 | const header = encoder.encode(`${type} ${content.length}\0`); |
| 47 | const full = new Uint8Array(header.length + content.length); |
| 48 | full.set(header, 0); |
| 49 | full.set(content, header.length); |
| 50 | return sha1(full); |
| 51 | } |
| 52 |