diff --git a/src/assertions.ts b/src/assertions.ts
index 5da0178..609cd4f 100644
--- a/src/assertions.ts
+++ b/src/assertions.ts
@@ -45,7 +45,7 @@ export const documentStateIsValid = async (doc: any, updateKeys: string[], witne
     if (proof.type !== 'DataIntegrityProof') {
       throw new Error(`Unknown proof type ${proof.type}`);
     }
-    if (proof.proofPurpose !== 'authentication') {
+    if (proof.proofPurpose !== 'authentication' && proof.proofPurpose !== 'assertionMethod') {
       throw new Error(`Unknown proof purpose ${proof.proofPurpose}`);
     }
     if (proof.cryptosuite !== 'eddsa-jcs-2022') {
diff --git a/src/cryptography.ts b/src/cryptography.ts
index 5921b06..2fddc8c 100644
--- a/src/cryptography.ts
+++ b/src/cryptography.ts
@@ -14,7 +14,7 @@ export const createSigner = (vm: VerificationMethod, useStatic: boolean = true)
         cryptosuite: 'eddsa-jcs-2022',
         verificationMethod: useStatic ? `did:key:${vm.publicKeyMultibase}#${vm.publicKeyMultibase}` : vm.id,
         created: createDate(),
-        proofPurpose: 'authentication'       
+        proofPurpose: 'assertionMethod'       
       }
       const dataHash = createHash('sha256').update(canonicalize(doc)).digest();
       const proofHash = createHash('sha256').update(canonicalize(proof)).digest();
@@ -41,7 +41,7 @@ export const generateEd25519VerificationMethod = async (): Promise<VerificationM
     type: "Multikey",
     publicKeyMultibase,
     secretKeyMultibase,
-    purpose: 'authentication'
+    purpose: 'assertionMethod'
   };
 }
 
diff --git a/test/fixtures/not-authorized.log b/test/fixtures/not-authorized.log
index 42950d5..a3e3dcb 100644
--- a/test/fixtures/not-authorized.log
+++ b/test/fixtures/not-authorized.log
@@ -1,2 +1,2 @@
-{"versionId":"1-QmX2pKGjDG6NTXFnPTHkBJ7Mmc2iwJQkvi35xEw5Qu34x7","versionTime":"2024-10-16T19:49:14Z","parameters":{"method":"did:tdw:0.4","scid":"QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb","updateKeys":["z6MkimixB3LLRtw2X8t8TachAsvP8ozrr1duC9kcgEFXSLW2"],"portable":false,"prerotation":false,"nextKeyHashes":[],"witnesses":[],"witnessThreshold":0,"deactivated":false},"state":{"@context":["https://www.w3.org/ns/did/v1","https://w3id.org/security/multikey/v1"],"id":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","controller":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","authentication":["did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#gEFXSLW2","did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#drUP7r5G"],"verificationMethod":[{"id":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#gEFXSLW2","controller":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","type":"Multikey","publicKeyMultibase":"z6MkimixB3LLRtw2X8t8TachAsvP8ozrr1duC9kcgEFXSLW2"},{"id":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#drUP7r5G","controller":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","type":"Multikey","publicKeyMultibase":"z6MkjebqPXBJ8FFog66DKBFCan4g9iPnG1dbjY5adrUP7r5G"}]},"proof":[{"type":"DataIntegrityProof","cryptosuite":"eddsa-jcs-2022","verificationMethod":"did:key:z6MkimixB3LLRtw2X8t8TachAsvP8ozrr1duC9kcgEFXSLW2#z6MkimixB3LLRtw2X8t8TachAsvP8ozrr1duC9kcgEFXSLW2","created":"2024-10-16T19:49:14Z","proofPurpose":"authentication","proofValue":"z4or9CsM7NMyeLid5SENnbfCHGFd1hZamHvdm9iAEaoGK3bAagkxCQceNrxvQxYxCraMPWstSUrjn9XJY3WrxnzWU"}]}
-{"versionId":"2-Qmbwu3Vrr3zdSjD994m1pu4BQSGZGXtMZrfuQh4GmXqUMd","versionTime":"2024-10-16T19:49:14Z","parameters":{"witnesses":[],"witnessThreshold":0},"state":{"@context":["https://www.w3.org/ns/did/v1","https://w3id.org/security/multikey/v1"],"id":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","controller":["did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com"],"authentication":["did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#GV4js1Ua","did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#G9AguCS3"],"verificationMethod":[{"id":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#GV4js1Ua","controller":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","type":"Multikey","publicKeyMultibase":"z6MkgNAsxqZoFt6dbEGCcZ6NZsFtHQpdCjUgmcG3GV4js1Ua"},{"id":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com#G9AguCS3","controller":"did:tdw:QmdM16VTQBmiy8Errf87Vkp6XGx6CspGTrfVDkXi1BRHbb:example.com","type":"Multikey","publicKeyMultibase":"z6Mkvm7Wxo58rHambdmSiMTxQF7m1pLxvCK7iAMmG9AguCS3"}]},"proof":[{"type":"DataIntegrityProof","cryptosuite":"eddsa-jcs-2022","verificationMethod":"did:key:z6MkjebqPXBJ8FFog66DKBFCan4g9iPnG1dbjY5adrUP7r5G#z6MkjebqPXBJ8FFog66DKBFCan4g9iPnG1dbjY5adrUP7r5G","created":"2024-10-16T19:49:14Z","proofPurpose":"authentication","proofValue":"z3GQFTrs8cudPLizGHWbSuMpqFoWcCxBFpCQGHLG1U9jwiDm5zQuhMyQHLJsD5sPz13k9fEBgM5EaXneTNAbc7G4a"}]}
+{"versionId":"1-QmbHUDLxTJCeKX3oACyabxT41b59dBeyVmGFUbYHheyXzZ","versionTime":"2024-10-25T18:45:30Z","parameters":{"method":"did:tdw:0.4","scid":"QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q","updateKeys":["z6MkmGhgCBEntnVBDJxRuzmiQegAW9CjxiNBghfQkuXz1KAL"],"portable":false,"prerotation":false,"nextKeyHashes":[],"witnesses":[],"witnessThreshold":0,"deactivated":false},"state":{"@context":["https://www.w3.org/ns/did/v1","https://w3id.org/security/multikey/v1"],"id":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","controller":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","assertionMethod":["did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#kuXz1KAL","did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#zZHqtfrA"],"verificationMethod":[{"id":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#kuXz1KAL","controller":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","type":"Multikey","publicKeyMultibase":"z6MkmGhgCBEntnVBDJxRuzmiQegAW9CjxiNBghfQkuXz1KAL"},{"id":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#zZHqtfrA","controller":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","type":"Multikey","publicKeyMultibase":"z6MkoQuMZHARUzhqbFyz8R4S4XZtrZdXDNGvsPoMzZHqtfrA"}]},"proof":[{"type":"DataIntegrityProof","cryptosuite":"eddsa-jcs-2022","verificationMethod":"did:key:z6MkmGhgCBEntnVBDJxRuzmiQegAW9CjxiNBghfQkuXz1KAL#z6MkmGhgCBEntnVBDJxRuzmiQegAW9CjxiNBghfQkuXz1KAL","created":"2024-10-25T18:45:30Z","proofPurpose":"assertionMethod","proofValue":"z4gL79eB3tnnHm8UPnxRPf4Q6P2E8t3YSxbF76MX2TG3acDDY8ZdjFo8XdbVPPqt49j5KacX5zVbawNmqBZb1rrdK"}]}
+{"versionId":"2-Qmdxp9ccKBcsCvWS1J4CZJLSLb7xwbVDnbrVK9vvVdk8hk","versionTime":"2024-10-25T18:45:30Z","parameters":{"witnesses":[],"witnessThreshold":0},"state":{"@context":["https://www.w3.org/ns/did/v1","https://w3id.org/security/multikey/v1"],"id":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","controller":["did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com"],"assertionMethod":["did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#t9eqqUNt","did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#aKfrG3z9"],"verificationMethod":[{"id":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#t9eqqUNt","controller":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","type":"Multikey","publicKeyMultibase":"z6MknCCJKC4F9JkRPpCiAVq7zJjU68yuvvj2x9ght9eqqUNt"},{"id":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com#aKfrG3z9","controller":"did:tdw:QmZnNM9Fzy5DU61AXBxtHbReZFMoEuS636s9HsxfJZbF9q:example.com","type":"Multikey","publicKeyMultibase":"z6Mkpec8gRmSA83WzQj36Tuhaa4mQLXuyuB76QipaKfrG3z9"}]},"proof":[{"type":"DataIntegrityProof","cryptosuite":"eddsa-jcs-2022","verificationMethod":"did:key:z6MkoQuMZHARUzhqbFyz8R4S4XZtrZdXDNGvsPoMzZHqtfrA#z6MkoQuMZHARUzhqbFyz8R4S4XZtrZdXDNGvsPoMzZHqtfrA","created":"2024-10-25T18:45:30Z","proofPurpose":"assertionMethod","proofValue":"z3yyXeh9y4bibGaJWkrWBi7A3fG2TnRDtuoWUzvZFo91yUBqs8vuZEEqRTT27FjMpusJU1VWf8WWJu7N3LBLphtyZ"}]}
diff --git a/test/happy-path.test.ts b/test/happy-path.test.ts
index 271e0cc..1b2d1cf 100644
--- a/test/happy-path.test.ts
+++ b/test/happy-path.test.ts
@@ -230,7 +230,7 @@ test("Update DID (add external controller)", async () => {
     didLog = [...updatedLog];
     expect(updatedDID).toBe(did);
     expect(updatedDoc.controller).toContain(externalAuthKey.controller);
-    expect(updatedDoc.authentication[1]).toContain(externalAuthKey.controller!.slice(-6));
+    expect(updatedDoc.assertionMethod[1]).toContain(externalAuthKey.controller!.slice(-6));
     expect(updatedDoc.verificationMethod[1].controller).toBe(externalAuthKey.controller);
 
     expect(meta.versionId.split('-')[0]).toBe("5");