Merge pull request #255 from openpassport-org/feature/sha384_sha512

Sha384 & sha512 circuits

common/src/utils/shaPad.ts

@@ -21,6 +21,55 @@ export function shaPad(prehash_prepad_m: Uint8Array, maxShaBytes: number): [Uint
   return [prehash_prepad_m, messageLen];
 }
 
+export function sha384_512Pad(prehash_prepad_m: Uint8Array, maxShaBytes: number): [Uint8Array, number] {
+  // Length in bits before padding
+  let length_bits = prehash_prepad_m.length * 8;
+  
+  // For SHA-384, length is stored in 128 bits (16 bytes)
+  let length_in_bytes = int128toBytes(length_bits);
+  
+  // Add the 1 bit (as a byte with value 128)
+  prehash_prepad_m = mergeUInt8Arrays(prehash_prepad_m, int8toBytes(2 ** 7));
+  
+  // Add padding zeros until total length is congruent to 896 mod 1024
+  while ((prehash_prepad_m.length * 8 + length_in_bytes.length * 8) % 1024 !== 0) {
+    prehash_prepad_m = mergeUInt8Arrays(prehash_prepad_m, int8toBytes(0));
+  }
+  
+  // Append the length
+  prehash_prepad_m = mergeUInt8Arrays(prehash_prepad_m, length_in_bytes);
+  
+  // Verify padding is correct (multiple of 1024 bits)
+  assert((prehash_prepad_m.length * 8) % 1024 === 0, "Padding did not complete properly!");
+  
+  let messageLen = prehash_prepad_m.length;
+  
+  // Pad to max length if needed
+  while (prehash_prepad_m.length < maxShaBytes) {
+    prehash_prepad_m = mergeUInt8Arrays(prehash_prepad_m, int128toBytes(0));
+  }
+  
+  assert(
+    prehash_prepad_m.length === maxShaBytes,
+    `Padding to max length did not complete properly! Your padded message is ${prehash_prepad_m.length} long but max is ${maxShaBytes}!`
+  );
+  
+  return [prehash_prepad_m, messageLen];
+}
+
+// Helper function to convert 128-bit length to bytes
+function int128toBytes(x: number): Uint8Array {
+  const buffer = new ArrayBuffer(16);
+  const view = new DataView(buffer);
+  
+  // Write high 64 bits
+  view.setBigUint64(0, BigInt(0), false);
+  // Write low 64 bits
+  view.setBigUint64(8, BigInt(x), false);
+  
+  return new Uint8Array(buffer);
+}
+
 // Works only on 32 bit sha text lengths
 export function int64toBytes(num: number): Uint8Array {
   let arr = new ArrayBuffer(8); // an Int32 takes 4 bytes