2 files changed, 37 insertions, 0 deletions
diff --git a/src/helpers/getCertificateInfo.ts b/src/helpers/getCertificateInfo.ts
new file mode 100644
index 0000000..b7a0ed0
--- /dev/null
+++ b/src/helpers/getCertificateInfo.ts
@@ -0,0 +1,31 @@
+import jsrsasign from 'jsrsasign';
+
+import { CertificateInfo } from '@types';
+
+/**
+ * Extract PEM certificate info
+ *
+ * @param pemCertificate Result from call to `convertASN1toPEM(x5c[0])`
+ */
+export default function getCertificateInfo(pemCertificate: string): CertificateInfo {
+  const subjectCert = new jsrsasign.X509();
+  subjectCert.readCertPEM(pemCertificate);
+
+  const subjectString = subjectCert.getSubjectString();
+  const subjectParts = subjectString.slice(1).split('/');
+
+  const subject: { [key: string]: string } = {};
+  subjectParts.forEach((field) => {
+    const [key, val] = field.split('=');
+    subject[key] = val;
+  });
+
+  const { getVersion } = subjectCert;
+  const basicConstraintsCA = !!subjectCert.getExtBasicConstraints().cA;
+
+  return {
+    subject,
+    version: getVersion(),
+    basicConstraintsCA,
+  };
+}
diff --git a/src/types.ts b/src/types.ts
index 927cdf4..0379ced 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -65,3 +65,9 @@ export type VerifiedAttestation = {
     base64CredentialID: string,
   },
 };
+
+export type CertificateInfo = {
+  subject: { [key: string]: string },
+  version: number,
+  basicConstraintsCA: boolean,
+};