chore: added rawPublicKeyHexFromAsn1Der function

packages/key-utils/src/functions.ts

@@ -350,3 +350,38 @@ export const padLeft = (args: { data: string; size?: number; padString?: string
   const length = padString.length
   return padString.repeat((size - data.length) / length) + data
 }
+
+
+/**
+ * This function converts a DER encoded ASN.1 formatted public key to a raw public key
+ * @param derKey
+ */
+export const rawPublicKeyHexFromAsn1Der = (derKey: Uint8Array): string => {
+  if (derKey[0] !== 0x30) {
+    throw new Error('Invalid DER encoding: Expected to start with sequence tag')
+  }
+
+  // Find the start of the bit string containing the public key
+  let index = 2 // Skip sequence tag and length
+  while (index < derKey.length) {
+    if (derKey[index] === 0x03) { // Bit string tag
+      break
+    }
+    index++
+  }
+
+  if (index >= derKey.length) {
+    throw new Error('Invalid DER encoding: Bit string not found')
+  }
+
+  // Skip bit string tag and length
+  index += 2
+
+  // Skip unused bits byte
+  index++
+
+  // Convert the remaining bytes to a hex string
+  return Array.from(derKey.slice(index))
+    .map(byte => byte.toString(16).padStart(2, '0'))
+    .join('')
+}

packages/kms-musap-rn/src/MusapKeyManagerSystem.ts

@@ -15,7 +15,7 @@ import { AbstractKeyManagementSystem } from '@veramo/key-manager'
 import { TextDecoder } from 'text-encoding'
 import { Loggers } from '@sphereon/ssi-types'
 import { KeyMetadata } from './index'
-import { PEMToHex } from '@sphereon/ssi-sdk-ext.key-utils'
+import { rawPublicKeyHexFromAsn1Der } from '@sphereon/ssi-sdk-ext.key-utils'
 
 export const logger = Loggers.DEFAULT.get('sphereon:musap-rn-kms')
 
@@ -133,7 +133,7 @@ export class MusapKeyManagementSystem extends AbstractKeyManagementSystem {
     const keyInfo: Partial<ManagedKeyInfo> = {
       kid: args.keyId,
       type: this.mapAlgorithmTypeToKeyType(args.algorithm),
-      publicKeyHex: PEMToHex( args.publicKey.pem),
+      publicKeyHex: rawPublicKeyHexFromAsn1Der(args.publicKey.der),
       meta: {
         ...args,
       },