diff --git a/CHANGELOG.md b/CHANGELOG.md
index e65dd5b..a3ede72 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # ssi Changelog
 
+## 5.3.0 - 
+### Added
+- Add `IKeyAgreementKeyPair2020` export.
+
 ## 5.2.0 - 2025-10-15
 ### Added
 - Add `identifier` property to `IOpenBadgeSubject` export.
diff --git a/README.md b/README.md
index ab57bb8..feec059 100644
--- a/README.md
+++ b/README.md
@@ -92,6 +92,8 @@ const vp = req.body.presentation as IVerifiablePresentation
 * `IVerifiableCredential` and `IVerifiablePresentation`
 * `IOpenBadgeCredentialV3` (for OBv3 VCs)
 * `IDidCoreDocument` and its children, `IDidDocument_v1_0` and `IDidDocument_v1_1`
+* `IKeyPair` and its children, such as `IVerificationKeyPair2020` and `IKeyAgreementKeyPair2020`
+* `ISigner`
 * ... others (see individual exports in `/src`)
 
 ## Contribute
diff --git a/src/KeyPair.ts b/src/KeyPair.ts
index 2412475..2d99085 100644
--- a/src/KeyPair.ts
+++ b/src/KeyPair.ts
@@ -25,9 +25,15 @@ export interface IVerificationKeyPair2018 extends IPublicKey2018 {
 }
 
 export interface IPublicKey2020 extends IKeyPairCore {
-  // Used by Ed25519VerificationKey2020
+  // Used by Ed25519VerificationKey2020 and X25519KeyAgreementKey2020
   publicKeyMultibase?: string
 }
+
+export interface IKeyAgreementKeyPair2020 extends IPublicKey2020 {
+  // Used by X25519KeyAgreementKey2020
+  privateKeyMultibase?: string
+}
+
 export interface IVerificationKeyPair2020 extends IPublicKey2020 {
   // Used by Ed25519VerificationKey2020
   privateKeyMultibase?: string