add subjects option to attest

Signed-off-by: Adam Nauth <Forrin@users.noreply.github.com>

packages/attest/__tests__/intoto.test.ts

@@ -17,7 +17,7 @@ describe('buildIntotoStatement', () => {
   }
 
   it('returns an intoto statement', () => {
-    const statement = buildIntotoStatement(subject, predicate)
+    const statement = buildIntotoStatement([subject], predicate)
     expect(statement).toMatchSnapshot()
   })
 })

packages/attest/__tests__/provenance.test.ts

@@ -5,6 +5,7 @@ import nock from 'nock'
 import {MockAgent, setGlobalDispatcher} from 'undici'
 import {SIGSTORE_PUBLIC_GOOD, signingEndpoints} from '../src/endpoints'
 import {attestProvenance, buildSLSAProvenancePredicate} from '../src/provenance'
+import type {Subject} from '../src/shared.types'
 
 describe('provenance functions', () => {
   const originalEnv = process.env
@@ -79,6 +80,22 @@ describe('provenance functions', () => {
       sha256: '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
     }
 
+    const subjects: Subject[] = [
+      {
+        name: 'subjective',
+        digest: {
+          sha256:
+            '7d070f6b64d9bcc530fe99cc21eaaa4b3c364e0b2d367d7735671fa202a03b32'
+        }
+      },
+      {
+        name: 'subject_two',
+        digest: {
+          gitcommit: 'c6b487124a61d7dc6c7bd6ea0208368af3513a6e'
+        }
+      }
+    ]
+
     // Fake an OIDC token
     const oidcPayload = {sub: 'foo@bar.com', iss: ''}
     const oidcToken = `.${Buffer.from(JSON.stringify(oidcPayload)).toString(
@@ -114,8 +131,7 @@ describe('provenance functions', () => {
       describe('when the sigstore instance is explicitly set', () => {
         it('attests provenance', async () => {
           const attestation = await attestProvenance({
-            subjectName,
-            subjectDigest,
+            subjects,
             token: 'token',
             sigstore: 'github',
             issuer

packages/attest/src/attest.ts

@@ -15,10 +15,16 @@ const INTOTO_PAYLOAD_TYPE = 'application/vnd.in-toto+json'
  */
 export type AttestOptions = {
   // The name of the subject to be attested.
-  subjectName: string
+  // @deprecated see 'subjects'
+  subjectName?: string
   // The digest of the subject to be attested. Should be a map of digest
   // algorithms to their hex-encoded values.
-  subjectDigest: Record<string, string>
+  // @deprecated see 'subjects'
+  subjectDigest?: Record<string, string>
+  // The subjects to be attested
+  // Includes the digest(s) of the subject to be attested. Should be a map of digest
+  // algorithms to their hex-encoded values.
+  subjects?: Subject[]
   // Content type of the predicate being attested.
   predicateType: string
   // Predicate to be attested.
@@ -40,10 +46,18 @@ export type AttestOptions = {
  * @returns A promise that resolves to the attestation.
  */
 export async function attest(options: AttestOptions): Promise<Attestation> {
-  const subject: Subject = {
+  let subject = [] as Subject[]
+  if (options.subjects && options.subjects.length > 0) {
+    subject = options.subjects
+  } else if (options.subjectName && options.subjectDigest) {
+    subject = [
+      {
         name: options.subjectName,
         digest: options.subjectDigest
       }
+    ]
+  }
+
   const predicate: Predicate = {
     type: options.predicateType,
     params: options.predicate

packages/attest/src/intoto.ts

@@ -20,12 +20,12 @@ export type InTotoStatement = {
  * @returns The constructed in-toto statement.
  */
 export const buildIntotoStatement = (
-  subject: Subject,
+  subject: Subject[],
   predicate: Predicate
 ): InTotoStatement => {
   return {
     _type: INTOTO_STATEMENT_V1_TYPE,
-    subject: [subject],
+    subject,
     predicateType: predicate.type,
     predicate: predicate.params
   }