diff --git a/packages/mdl-mdoc/src/functions/index.ts b/packages/mdl-mdoc/src/functions/index.ts
index 64aee031..b14e526b 100644
--- a/packages/mdl-mdoc/src/functions/index.ts
+++ b/packages/mdl-mdoc/src/functions/index.ts
@@ -5,11 +5,11 @@ import {
   getSubjectDN,
   pemOrDerToX509Certificate,
   validateX509CertificateChain,
-  X509ValidationResult,
+  X509ValidationResult
 } from '@sphereon/ssi-sdk-ext.x509-utils'
 import * as crypto from 'crypto'
 import { Certificate, CryptoEngine, setEngine } from 'pkijs'
-import { VerifyCertificateChainArgs } from '../types/ImDLMdoc'
+import { IRequiredContext, VerifyCertificateChainArgs } from '../types/ImDLMdoc'
 import CoseKeyCbor = com.sphereon.crypto.cose.CoseKeyCbor
 import CoseSign1Cbor = com.sphereon.crypto.cose.CoseSign1Cbor
 import ICoseKeyCbor = com.sphereon.crypto.cose.ICoseKeyCbor
@@ -25,24 +25,60 @@ import IX509ServiceJS = com.sphereon.crypto.IX509ServiceJS
 import IX509VerificationResult = com.sphereon.crypto.IX509VerificationResult
 import Jwk = com.sphereon.crypto.jose.Jwk
 import KeyInfo = com.sphereon.crypto.KeyInfo
+import ResolvedKeyInfo = com.sphereon.crypto.ResolvedKeyInfo
 import X509VerificationProfile = com.sphereon.crypto.X509VerificationProfile
+import DateTimeUtils = com.sphereon.kmp.DateTimeUtils
 import decodeFrom = com.sphereon.kmp.decodeFrom
+import encodeTo = com.sphereon.kmp.encodeTo
 import Encoding = com.sphereon.kmp.Encoding
 import LocalDateTimeKMP = com.sphereon.kmp.LocalDateTimeKMP
-import DateTimeUtils = com.sphereon.kmp.DateTimeUtils
 
 export class CoseCryptoService implements ICoseCryptoCallbackJS {
-  async signAsync<CborType>(input: ToBeSignedCbor, requireX5Chain: Nullable<boolean>): Promise<Int8Array> {
-    throw new Error('Method not implemented.')
+
+  constructor(private context?: IRequiredContext) {
+  }
+
+  setContext(context: IRequiredContext) {
+    this.context = context
+  }
+
+  async signAsync(input: ToBeSignedCbor, requireX5Chain: Nullable<boolean>): Promise<Int8Array> {
+    if (!this.context) {
+      throw Error('No context provided. Please provide a context with the setContext method or constructor')
+    }
+    const { keyInfo, alg, value } = input
+    let kmsKeyRef = keyInfo.kmsKeyRef ?? undefined
+    if (!kmsKeyRef) {
+      const key = keyInfo.key.copy(true)
+      if (key == null) {
+        return Promise.reject(Error('No key present in keyInfo. This implementation cannot sign without a key!'))
+      }
+      key.getJwkThumbprint()
+      const resolvedKeyInfo = ResolvedKeyInfo.Static.fromKeyInfo(keyInfo, key)
+      const jwkKeyInfo: ResolvedKeyInfo<Jwk> = CoseJoseKeyMappingService.toResolvedJwkKeyInfo(resolvedKeyInfo)
+      const kid = jwkKeyInfo.kid ?? undefined
+      if (!kid) {
+        return Promise.reject(Error('No kid present'))
+      }
+      kmsKeyRef = kid
+    }
+    const result = await this.context.agent.keyManagerSign({
+      algorithm: alg.jose!!.value,
+      data: encodeTo(value, Encoding.UTF8),
+      encoding: 'utf-8',
+      keyRef: kmsKeyRef!!
+    })
+    return decodeFrom(result, Encoding.UTF8)
+
   }
 
   async verify1Async<CborType>(
     input: CoseSign1Cbor<CborType>,
     keyInfo: IKeyInfo<ICoseKeyCbor>,
-    requireX5Chain: Nullable<boolean>,
+    requireX5Chain: Nullable<boolean>
   ): Promise<IVerifySignatureResult<ICoseKeyCbor>> {
     const getCertAndKey = async (
-      x5c: Nullable<Array<string>>,
+      x5c: Nullable<Array<string>>
     ): Promise<{
       issuerCert?: Certificate
       issuerPublicKey: CryptoKey
@@ -97,14 +133,14 @@ export class CoseCryptoService implements ICoseCryptoCallbackJS {
           crv,
           ...(jwk.x5c && { x5c: jwk.x5c }),
           ...(jwk.x && { x: jwk.x }),
-          ...(jwk.y && { y: jwk.y }),
+          ...(jwk.y && { y: jwk.y })
         } satisfies JsonWebKey,
         {
           name: keyAlg.value === 'EC' ? 'ECDSA' : keyAlg.value,
-          namedCurve: crv,
+          namedCurve: crv
         },
         true,
-        ['verify'],
+        ['verify']
       )
     }
 
@@ -116,11 +152,11 @@ export class CoseCryptoService implements ICoseCryptoCallbackJS {
     const valid = await crypto.subtle.verify(
       {
         ...issuerPublicKey.algorithm,
-        hash: crv?.includes('-') ? `SHA-${crv.split('-')[1]}` : 'SHA-256', // todo: this needs to be more robust
+        hash: crv?.includes('-') ? `SHA-${crv.split('-')[1]}` : 'SHA-256' // todo: this needs to be more robust
       },
       issuerPublicKey,
       decodeFrom(sign1Json.signature, Encoding.BASE64URL),
-      decodeFrom(recalculatedToBeSigned.base64UrlValue, Encoding.BASE64URL),
+      decodeFrom(recalculatedToBeSigned.base64UrlValue, Encoding.BASE64URL)
     )
 
     return {
@@ -128,12 +164,12 @@ export class CoseCryptoService implements ICoseCryptoCallbackJS {
       critical: true,
       error: !valid,
       message: `Signature of '${issuerCert ? getSubjectDN(issuerCert).DN : kid}' was ${valid ? '' : 'in'}valid`,
-      keyInfo: coseKeyInfo,
+      keyInfo: coseKeyInfo
     } satisfies IVerifySignatureResult<ICoseKeyCbor>
   }
 
   resolvePublicKeyAsync<KT extends com.sphereon.crypto.IKey>(
-    keyInfo: com.sphereon.crypto.IKeyInfo<KT>,
+    keyInfo: com.sphereon.crypto.IKeyInfo<KT>
   ): Promise<com.sphereon.crypto.IResolvedKeyInfo<KT>> {
     if (keyInfo.key) {
       return Promise.resolve(CoseJoseKeyMappingService.toResolvedKeyInfo(keyInfo, keyInfo.key))
@@ -163,16 +199,16 @@ export class X509CallbackService implements IX509ServiceJS {
    * @param verificationTime
    */
   async verifyCertificateChain({
-    chain,
-    trustAnchors = this.getTrustedCerts(),
-    verificationTime,
-    opts,
-  }: VerifyCertificateChainArgs): Promise<X509ValidationResult> {
+                                 chain,
+                                 trustAnchors = this.getTrustedCerts(),
+                                 verificationTime,
+                                 opts
+                               }: VerifyCertificateChainArgs): Promise<X509ValidationResult> {
     return await validateX509CertificateChain({
       chain,
       trustAnchors,
       verificationTime,
-      opts,
+      opts
     })
   }
 
@@ -184,7 +220,7 @@ export class X509CallbackService implements IX509ServiceJS {
     chainPEM: Nullable<string[]>,
     trustedCerts: Nullable<string[]>,
     verificationProfile?: X509VerificationProfile | undefined,
-    verificationTime?: Nullable<LocalDateTimeKMP>,
+    verificationTime?: Nullable<LocalDateTimeKMP>
   ): Promise<IX509VerificationResult<KeyType>> {
     const verificationAt = verificationTime ?? DateTimeUtils.Static.DEFAULT.dateTimeLocal()
     let chain: Array<string | Uint8Array> = []
@@ -198,7 +234,7 @@ export class X509CallbackService implements IX509ServiceJS {
       chain: chain, // The function will handle an empty array
       trustAnchors: trustedCerts ?? this.getTrustedCerts(),
       verificationTime: new Date(verificationAt.toEpochSeconds().toULong() * 1000),
-      opts: { trustRootWhenNoAnchors: true },
+      opts: { trustRootWhenNoAnchors: true }
     })
 
     const cert: CertificateInfo | undefined = result.certificateChain ? result.certificateChain[result.certificateChain.length - 1] : undefined
@@ -210,7 +246,7 @@ export class X509CallbackService implements IX509ServiceJS {
       critical: result.critical,
       message: result.message,
       error: result.error,
-      verificationTime: verificationAt,
+      verificationTime: verificationAt
     } satisfies IX509VerificationResult<KeyType>
   }
 
@@ -253,6 +289,6 @@ const defaultCryptoEngine = () => {
 
 defaultCryptoEngine()
 
-// We register the services with the mDL/mdoc library
+// We register the services with the mDL/mdoc library. Please note that the context is not passed in, meaning we cannot sign by default.
 DefaultCallbacks.setCoseCryptoDefault(new CoseCryptoService())
 DefaultCallbacks.setX509Default(new X509CallbackService())