diff --git a/signature-envelope-cose.md b/signature-envelope-cose.md
index 5612247b..1c6839d1 100644
--- a/signature-envelope-cose.md
+++ b/signature-envelope-cose.md
@@ -90,9 +90,9 @@ Note: The above examples are represented using the [extended CBOR diagnostic not
 - **[`crit`](https://datatracker.ietf.org/doc/html/rfc8152#section-3.1)** (*array of int/tstr*): This REQUIRED parameter (label `2`) lists the header parameters that implementations MUST understand and process. It MUST only contain parameters apart from integer labels in the range of 0 to 8. This header MUST contain `io.cncf.notary.signingScheme` which is a required critical header, and optionally contain `io.cncf.notary.authenticSigningTime` and `io.cncf.notary.expiry` if these critical headers are present in the signature.
 - **[`content type`](https://datatracker.ietf.org/doc/html/rfc8152#section-3.1)** (*tstr*): The REQUIRED parameter content type (label `3`) is used to declare the media type of the secured content (the payload). The supported value is `application/vnd.cncf.notary.payload.v1+json`.
 - **`io.cncf.notary.signingScheme`** (*tstr*, critical): This REQUIRED header specifies the [Notary v2 Signing Scheme](./signing-scheme.md) used by the signature. Supported values are `notary.x509` and `notary.x509.signingAuthority`.
-- **`io.cncf.notary.signingTime`** (*date/time*): This header specifies the time at which the signature was generated. This is an untrusted date/time, and therefore not used in trust decisions. Its value is a [RFC 3339](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6) formatted date time. This claim is REQUIRED and only valid when signing scheme is `notary.x509`.
-- **`io.cncf.notary.authenticSigningTime`** (*date/time*, critical): This header specifies the authenticated time at which the signature was generated. Its value is a [RFC 3339](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6) formatted date time. This claim is REQUIRED and only valid when signing scheme is `notary.x509.signingAuthority` .
-- **`io.cncf.notary.expiry`** (*date/time*, critical): This OPTIONAL header provides a "best by use" time for the artifact, as defined by the signer. Its value is a [RFC 3339](https://datatracker.ietf.org/doc/html/rfc3339#section-5.6) formatted date time.
+- **`io.cncf.notary.signingTime`** (*uint*): This header specifies the time at which the signature was generated. This is an untrusted timestamp, and therefore not used in trust decisions. Its value is the number of seconds from `1970-01-01T00:00Z` in UTC time, commonly known as UNIX timestamp. This claim is REQUIRED and only valid when signing scheme is `notary.x509`.
+- **`io.cncf.notary.authenticSigningTime`** (*uint*, critical): This header specifies the authenticated time at which the signature was generated. Its value is the number of seconds from `1970-01-01T00:00Z` in UTC time, commonly known as UNIX timestamp. This claim is REQUIRED and only valid when signing scheme is `notary.x509.signingAuthority` .
+- **`io.cncf.notary.expiry`** (*uint*, critical): This OPTIONAL header provides a "best by use" time for the artifact, as defined by the signer. Its value is the number of seconds from `1970-01-01T00:00Z` in UTC time, commonly known as UNIX timestamp.
 
 ## Unprotected Headers