HKDF: remove fallback for Node 14

v6 drops support for Node 14, which does not include SubtleCrypto
openpgpjs · Aug 3, 2023 · b9b88a2 · b9b88a2
1 parent 89ce7f4
commit b9b88a2
Showing 1 changed file with 4 additions and 44 deletions.
diff --git a/src/crypto/hkdf.js b/src/crypto/hkdf.js
@@ -8,53 +8,13 @@ import util from '../util';
 
 const webCrypto = util.getWebCrypto();
 const nodeCrypto = util.getNodeCrypto();
-const nodeSubtleCrypto = nodeCrypto && nodeCrypto.webcrypto && nodeCrypto.webcrypto.subtle;
 
 export default async function HKDF(hashAlgo, inputKey, salt, info, outLen) {
   const hash = enums.read(enums.webHash, hashAlgo);
   if (!hash) throw new Error('Hash algo not supported with HKDF');
 
-  if (webCrypto || nodeSubtleCrypto) {
-    const crypto = webCrypto || nodeSubtleCrypto;
-    const importedKey = await crypto.importKey('raw', inputKey, 'HKDF', false, ['deriveBits']);
-    const bits = await crypto.deriveBits({ name: 'HKDF', hash, salt, info }, importedKey, outLen * 8);
-    return new Uint8Array(bits);
-  }
-
-  if (nodeCrypto) {
-    const hashAlgoName = enums.read(enums.hash, hashAlgo);
-    // Node-only HKDF implementation based on https://www.rfc-editor.org/rfc/rfc5869
-
-    const computeHMAC = (hmacKey, hmacMessage) => nodeCrypto.createHmac(hashAlgoName, hmacKey).update(hmacMessage).digest();
-    // Step 1: Extract
-    // PRK = HMAC-Hash(salt, IKM)
-    const pseudoRandomKey = computeHMAC(salt, inputKey);
-
-    const hashLen = pseudoRandomKey.length;
-
-    // Step 2: Expand
-    // HKDF-Expand(PRK, info, L) -> OKM
-    const n = Math.ceil(outLen / hashLen);
-    const outputKeyingMaterial = new Uint8Array(n * hashLen);
-
-    // HMAC input buffer updated at each iteration
-    const roundInput = new Uint8Array(hashLen + info.length + 1);
-    // T_i and last byte are updated at each iteration, but `info` remains constant
-    roundInput.set(info, hashLen);
-
-    for (let i = 0; i < n; i++) {
-      // T(0) = empty string (zero length)
-      // T(i) = HMAC-Hash(PRK, T(i-1) | info | i)
-      roundInput[roundInput.length - 1] = i + 1;
-      // t = T(i+1)
-      const t = computeHMAC(pseudoRandomKey, i > 0 ? roundInput : roundInput.subarray(hashLen));
-      roundInput.set(t, 0);
-
-      outputKeyingMaterial.set(t, i * hashLen);
-    }
-
-    return outputKeyingMaterial.subarray(0, outLen);
-  }
-
-  throw new Error('No HKDF implementation available');
+  const crypto = webCrypto || nodeCrypto.webcrypto.subtle;
+  const importedKey = await crypto.importKey('raw', inputKey, 'HKDF', false, ['deriveBits']);
+  const bits = await crypto.deriveBits({ name: 'HKDF', hash, salt, info }, importedKey, outLen * 8);
+  return new Uint8Array(bits);
 }