fix(docs): sha256 packages, clarify hmac support (#455)

* sha256 packages: clarify hmac support

* fix(docs): sha256 packages, clarify hmac support

Co-authored-by: Lorentzen <crlorent@amazon.com>
Co-authored-by: Andrew Jewell <107044381+ajewellamz@users.noreply.github.com>

packages/sha256-browser/README.md

@@ -6,6 +6,7 @@ to provide a consistent interface for SHA256.
 
 ## Usage
 
+- To hash "some data"
 ```
 import {Sha256} from '@aws-crypto/sha256-browser'
 
@@ -15,6 +16,16 @@ const result = await hash.digest();
 
 ```
 
+- To hmac "some data" with "a key"
+```
+import {Sha256} from '@aws-crypto/sha256-browser'
+
+const hash = new Sha256('a key');
+hash.update('some data');
+const result = await hash.digest();
+
+```
+
 ## Test
 
 `npm test`

packages/sha256-js/README.md

@@ -4,6 +4,7 @@ A pure JS implementation SHA256.
 
 ## Usage
 
+- To hash "some data"
 ```
 import {Sha256} from '@aws-crypto/sha256-js';
 
@@ -13,6 +14,16 @@ const result = await hash.digest();
 
 ```
 
+- To hmac "some data" with "a key"
+```
+import {Sha256} from '@aws-crypto/sha256-js';
+
+const hash = new Sha256('a key');
+hash.update('some data');
+const result = await hash.digest();
+
+```
+
 ## Test
 
 `npm test`

packages/sha256-js/test/jsSha256.test.ts

@@ -82,7 +82,7 @@ describe("Sha256", () => {
 
   idx = 0;
   for (const [key, data, result] of hmacTestVectors) {
-    it("should match known hash calculations: " + idx++, async () => {
+    it("should match known hmac calculations: " + idx++, async () => {
       const hash = new Sha256(key);
       hash.update(data);
       expect(await hash.digest()).to.deep.equal(result);

packages/sha256-universal/README.md

@@ -4,6 +4,7 @@ A consistent interface for SHA256 across browsers and NodeJs
 
 ## Usage
 
+- To hash "some data"
 ```
 import {Sha256} from '@aws-crypto/sha256-universal'
 
@@ -13,6 +14,16 @@ const result = await hash.digest();
 
 ```
 
+- To hmac "some data" with "a key"
+```
+import {Sha256} from '@aws-crypto/sha256-universal'
+
+const hash = new Sha256('a key');
+hash.update('some data');
+const result = await hash.digest();
+
+```
+
 ## Test
 
 `npm test`