From cd930efb2ce60f658a1b519a9b8e8d84feb85e46 Mon Sep 17 00:00:00 2001
From: Philipp Gackstatter <philipp.gackstatter@iota.org>
Date: Wed, 24 Jan 2024 15:18:39 +0100
Subject: [PATCH] Remove Ed25519 Public Key Block Issuer Key

---
 tips/TIP-0042/tip-0042.md | 56 ++++++++++-----------------------------
 1 file changed, 14 insertions(+), 42 deletions(-)

diff --git a/tips/TIP-0042/tip-0042.md b/tips/TIP-0042/tip-0042.md
index 72739834b..b63cf1e72 100644
--- a/tips/TIP-0042/tip-0042.md
+++ b/tips/TIP-0042/tip-0042.md
@@ -194,7 +194,7 @@ locked to that account.
     <td valign="top">Block Issuer Keys <code>anyOf</code></td>
     <td colspan="2">
       <details>
-        <summary>Ed25519 Public Key Block Issuer Key</summary>
+        <summary>Ed25519 Public Key Hash Block Issuer Key</summary>
         <blockquote>A Block Issuer Key backed by an Ed25519 Public Key.</blockquote>
         <table>
           <tr>
@@ -211,12 +211,12 @@ locked to that account.
           <tr>
             <td>Block Issuer Key Type</td>
             <td>uint8</td>
-            <td>Set to <strong>value 0</strong> to denote an <i>Ed25519 Public Key Block Issuer Key</i>.</td>
+            <td>Set to <strong>value 0</strong> to denote an <i>Ed25519 Public Key Hash Block Issuer Key</i>.</td>
           </tr>
           <tr>
-            <td>Public Key</td>
+            <td>PubKeyHash</td>
             <td>ByteArray[32]</td>
-            <td>The raw bytes of the Ed25519 public key.</td>
+            <td>The raw bytes of the BLAKE2b-256 hash of the corresponding Ed25519 public key.</td>
           </tr>
         </table>
       </details>
@@ -618,7 +618,7 @@ outputs that are locked under _Account Address_ and it keeps track of controlled
                   <tr>
                     <td>Key</td>
                     <td>(uint8)ByteArray</td>
-                    <td>A string which may only consist of ASCII characters. A leading uint8 denotes its length.</td>
+                    <td>A string which may only consist of printable ASCII characters. A leading uint8 denotes its length.</td>
                   </tr>
                   <tr>
                     <td>Value</td>
@@ -653,7 +653,7 @@ outputs that are locked under _Account Address_ and it keeps track of controlled
           </tr>
           <tr>
             <td>Expiry Slot</td>
-            <td>uint64</td>
+            <td>uint32</td>
             <td>The slot index at which the <i>Block Issuer Feature</i> expires and can be removed.</td>
           </tr>
           <tr>
@@ -665,7 +665,7 @@ outputs that are locked under _Account Address_ and it keeps track of controlled
             <td valign="top">Block Issuer Keys <code>anyOf</code></td>
             <td colspan="2">
               <details>
-                <summary>Ed25519 Public Key Block Issuer Key</summary>
+                <summary>Ed25519 Public Key Hash Block Issuer Key</summary>
                 <blockquote>A Block Issuer Key backed by an Ed25519 Public Key.</blockquote>
                 <table>
                   <tr>
@@ -682,12 +682,12 @@ outputs that are locked under _Account Address_ and it keeps track of controlled
                   <tr>
                     <td>Block Issuer Key Type</td>
                     <td>uint8</td>
-                    <td>Set to <strong>value 0</strong> to denote an <i>Ed25519 Public Key Block Issuer Key</i>.</td>
+                    <td>Set to <strong>value 0</strong> to denote an <i>Ed25519 Public Key Hash Block Issuer Key</i>.</td>
                   </tr>
                   <tr>
-                    <td>Public Key</td>
+                    <td>PubKeyHash</td>
                     <td>ByteArray[32]</td>
-                    <td>The raw bytes of the Ed25519 public key.</td>
+                    <td>The raw bytes of the BLAKE2b-256 hash of the corresponding Ed25519 public key.</td>
                   </tr>
                 </table>
               </details>
@@ -844,7 +844,7 @@ outputs that are locked under _Account Address_ and it keeps track of controlled
                   <tr>
                     <td>Key</td>
                     <td>(uint8)ByteArray</td>
-                    <td>A string which may only consist of ASCII characters. A leading uint8 denotes its length.</td>
+                    <td>A string which may only consist of printable ASCII characters. A leading uint8 denotes its length.</td>
                   </tr>
                   <tr>
                     <td>Value</td>
@@ -1043,37 +1043,9 @@ creation and block issuer feature transition.
 
 ### Implicit Account Block Issuance
 
-An implicit account can issue blocks by using the public key from which the implicit account creation address was
-derived as a block issuer key. A separate block issuer key type is reserved for that, which is however never used in
-transactions directly.
-
-<details>
-  <summary>Ed25519 Public Key Hash Block Issuer Key</summary>
-  <blockquote>A block issuer key for issuing blocks from implicit accounts.</blockquote>
-</details>
-<table>
-  <tr>
-    <td>
-      <b>Name</b>
-    </td>
-    <td>
-      <b>Type</b>
-    </td>
-    <td>
-      <b>Description</b>
-    </td>
-  </tr>
-  <tr>
-    <td>Block Issuer Key Type</td>
-    <td>uint8</td>
-    <td>Set to <strong>value 1</strong> to denote an <i>Ed25519 Public Key Hash Block Issuer Key</i>.</td>
-  </tr>
-  <tr>
-    <td>PubKeyHash</td>
-    <td>ByteArray[32]</td>
-    <td>The raw bytes of the Implicit Account Creation Address which is the BLAKE2b-256 hash of the Ed25519 public key.</td>
-  </tr>
-</table>
+An implicit account can issue blocks by using the `PubKeyHash` of the _Implicit Account Creation Address_ itself as an
+_Ed25519 Public Key Hash Block Issuer Key_. Therefore, the block's signature must contain the public key from which the
+`PubKeyHash` was derived from and the signature must be computed from the corresponding private key.
 
 # Migration