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add hmacSha1 function #155

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add hmacSha1 function #155

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57 changes: 40 additions & 17 deletions src/lib/crypto/hmac.ts
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Original file line number Diff line number Diff line change
@@ -1,9 +1,10 @@
import {
sha1 as internalSha1,
sha256 as internalSha256,
sha512 as internalSha512,
} from '../crypto/default-crypto-instances.js';
import { flattenBinArray } from '../format/format.js';
import type { Sha256, Sha512 } from '../lib.js';
import type { Sha1, Sha256, Sha512 } from '../lib.js';

export type HmacFunction = (
secret: Uint8Array,
Expand All @@ -23,24 +24,46 @@ export const instantiateHmacFunction =
hashFunction: (input: Uint8Array) => Uint8Array,
blockByteLength: number,
): HmacFunction =>
(secret, message) => {
const key = new Uint8Array(blockByteLength).fill(0);
// eslint-disable-next-line functional/no-expression-statements
key.set(secret.length > blockByteLength ? hashFunction(secret) : secret, 0);
(secret, message) => {
const key = new Uint8Array(blockByteLength).fill(0);
// eslint-disable-next-line functional/no-expression-statements
key.set(secret.length > blockByteLength ? hashFunction(secret) : secret, 0);

const innerPaddingFill = 0x36;
const innerPadding = new Uint8Array(blockByteLength).fill(innerPaddingFill);
// eslint-disable-next-line no-bitwise, @typescript-eslint/no-non-null-assertion
const innerPrefix = innerPadding.map((pad, index) => pad ^ key[index]!);
const innerContent = flattenBinArray([innerPrefix, message]);
const innerResult = hashFunction(innerContent);
const innerPaddingFill = 0x36;
const innerPadding = new Uint8Array(blockByteLength).fill(innerPaddingFill);
// eslint-disable-next-line no-bitwise, @typescript-eslint/no-non-null-assertion
const innerPrefix = innerPadding.map((pad, index) => pad ^ key[index]!);
const innerContent = flattenBinArray([innerPrefix, message]);
const innerResult = hashFunction(innerContent);

const outerPaddingFill = 0x5c;
const outerPadding = new Uint8Array(blockByteLength).fill(outerPaddingFill);
// eslint-disable-next-line no-bitwise, @typescript-eslint/no-non-null-assertion
const outerPrefix = outerPadding.map((pad, index) => pad ^ key[index]!);
return hashFunction(flattenBinArray([outerPrefix, innerResult]));
};
const outerPaddingFill = 0x5c;
const outerPadding = new Uint8Array(blockByteLength).fill(outerPaddingFill);
// eslint-disable-next-line no-bitwise, @typescript-eslint/no-non-null-assertion
const outerPrefix = outerPadding.map((pad, index) => pad ^ key[index]!);
return hashFunction(flattenBinArray([outerPrefix, innerResult]));
};

const sha1BlockByteLength = 64;

/**
* Create a hash-based message authentication code using HMAC-SHA1.
* Returns a 32-byte Uint8Array.
*
* Secrets longer than the block byte-length (64 bytes) are hashed before
* use, shortening their length to the minimum recommended length (64 bytes).
* See `RFC 2104` for details.
*
* @param secret - the secret key (recommended length: 64 bytes)
* @param message - the message to authenticate
* @param sha1 - an implementation of Sha1 (defaults to the
* internal WASM implementation)
*/
export const hmacSha1 = (
secret: Uint8Array,
message: Uint8Array,
sha1: { hash: Sha1['hash'] } = internalSha1,
) =>
instantiateHmacFunction(sha1.hash, sha1BlockByteLength)(secret, message);

const sha256BlockByteLength = 64;

Expand Down