diff --git a/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt b/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt
index 84e8e2acf5..8c5500a7ff 100644
--- a/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt
+++ b/core/src/main/kotlin/net/corda/core/crypto/CompositeKey.kt
@@ -31,7 +31,13 @@ sealed class CompositeKey {
     /** Checks whether any of the given [keys] matches a leaf on the tree */
     fun containsAny(otherKeys: Iterable<PublicKey>) = keys.intersect(otherKeys).isNotEmpty()
 
-    // TODO: implement a proper encoding/decoding mechanism
+    /**
+     * This is generated by serializing the composite key with Kryo, and encoding the resulting bytes in base58.
+     * A custom serialization format is being used.
+     *
+     * TODO: follow the crypto-conditions ASN.1 spec, some changes are needed to be compatible with the condition
+     *       structure, e.g. mapping a PublicKey to a condition with the specific feature (ED25519).
+     */
     fun toBase58String(): String = Base58.encode(this.serialize().bytes)
 
     companion object {