Original text:
Issuers maintain an issuance key pair for the issuance protocol.  The Issuer public key is made available to all Clients in such a way that <del> key rotations and other updates are publicly visible.  The key material and protocol configuration that an Issuer uses to produce tokens corresponds to two different pieces of information. </del>  The issuance protocol in use; and As above, specific mechanisms for key management and discovery are out of scope for this document. <del> 3.2.2.2. Token issuance associates all issued tokens with a particular choice of key.  If an Issuer issues tokens with many keys, then this may harm the anonymity of the Client.  For example, they would be able to map the Client's access patterns by inspecting which key each token they possess has been issued under. To prevent against this, Issuers MUST only use one private key for issuing tokens at any given time.  Servers MAY use one or more keys for redemption to allow Issuers for seamless key rotation. Servers may rotate keys as a means of revoking tokens issued under old or otherwise expired keys.  Alternatively, Issuers may include expiration information as metadata alongside the token; See metadata for more discussion about metadata constraints.  Both techniques are equivalent since they cryptographically bind expiration to individual tokens.  Key rotations should be limited in frequency for similar reasons. </del> 3.2.3. Certain instantiations of the issuance protocol may permit public or 5.2. Issuer key rotation is important to hedge against long-term private <del> key compromise.  However, key rotation can also be used to segment Client anonymity sets.  In particular, when an Issuer rotates their key, any Client that invokes the issuance protocol in this key cycle will be part of a group of possible Clients owning valid tokens for this key.  To mechanize this attack strategy, an Issuer could introduce a key rotation policy that forces Clients into small key cycles, reducing the size of the anonymity set for these Clients. </del>  In general, key rotations represent a trade-off between Client <del> privacy and continued Issuer security.  Therefore, it is still important that key rotations occur on a regular cycle to reduce the harmfulness of an Issuer key compromise. With a large number of Clients, a minimum of one week gives a large enough window for Clients to participate in the issuance protocol and thus enjoy the anonymity guarantees of being part of a larger group. A maximum of 12 weeks limits the damage caused by a key compromise. If an Issuer realizes that a key compromise has occurred then the Issuer should generate a new key and make it available to Clients. If possible, it should invoke any revocation procedures that may apply for the old key. </del>  5.3.

Reviewer comments:
cc NAME
S3.2.2.2 states "Issuers MUST only use one private key for issuing tokens at any given time." The next section (3.2.3), however, suggests that multiple keys could be used to encode metadata, and indeed, I believe the latest draft of rate-limited tokens uses different issuance keys. These seem to be in conflict.

Revised text:
Issuers maintain an issuance key pair for the issuance protocol.  The Issuer public key is made available to all Clients in such a way that  <ins> key rotations and other updates are publicly visible.  See key- rotation-privacy for more considerations around Issuer key rotation. The key material and protocol configuration that an Issuer uses to produce tokens corresponds to two different pieces of information. </ins> The issuance protocol in use; and As above, specific mechanisms for key management and discovery are out of scope for this document.  3.2.3. Certain instantiations of the issuance protocol may permit public or 5.2. Issuer key rotation is important to hedge against long-term private  <ins> key compromise.  If an Issuer realizes that a key compromise has occurred then the Issuer should generate a new key and make it available to Clients.  If possible, it should invoke any revocation procedures that may apply for the old key. Key rotation can also be used to segment Client anonymity sets.  In particular, when an Issuer rotates their key, any Client that invokes the issuance protocol in this key cycle will be part of a group of possible Clients owning valid tokens for this key.  To mechanize this attack strategy, an Issuer could introduce a key rotation policy that forces Clients into small key cycles, reducing the size of the anonymity set for these Clients. </ins> In general, key rotations represent a trade-off between Client  <ins> privacy and Issuer security.  Therefore, it is still important that key rotations occur on a regular cycle to reduce the harmfulness of an Issuer key compromise.  If there are multiple Issuer keys in rotation, Clients can apply some form of consistency mechanism CONSISTENCY to ensure that they receive the same key as other Clients.  Likewise, Origins can use one or more public keys for redemption to support Issuer key rotation. </ins> 5.3.