Add support for EIP-2098 compact signatures (#2246).

ethers-io · Feb 18, 2022 · f26074b · f26074b
1 parent eb91d70
commit f26074b
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Showing 2 changed files with 31 additions and 9 deletions.
diff --git a/docs.wrm/api/utils/bytes.wrm b/docs.wrm/api/utils/bytes.wrm
@@ -38,8 +38,10 @@ _heading: Signature @<Signature>
 
 - **r** and **s** --- The x co-ordinate of **r** and the **s** value of the signature
 - **v** --- The parity of the y co-ordinate of **r**
-- **_vs** --- The [compact representation](link-eip-2098) of the **s** and **v**
+- **yParityAndS** --- The [compact representation](link-eip-2098) of the **s** and **v**
+- **_vs** --- Deprecated property; renamed to yParityAndS
 - **recoveryParam** --- The normalized (i.e. 0 or 1) value of **v**
+- **compact** - The full siggnature using [compact representation](link-eip-2098)
 
 _heading: Raw Signature @<signature-raw> @inherit<string\<[[DataHexString]]\<65\>\>>
 

diff --git a/packages/bytes/src.ts/index.ts b/packages/bytes/src.ts/index.ts
@@ -46,6 +46,9 @@ export interface Signature {
 
     recoveryParam: number;
     v: number;
+
+    yParityAndS: string
+    compact: string;
 }
 
 ///////////////////////////////
@@ -328,24 +331,38 @@ export function hexZeroPad(value: BytesLike, length: number): string {
 }
 
 export function splitSignature(signature: SignatureLike): Signature {
+
     const result = {
         r: "0x",
         s: "0x",
         _vs: "0x",
         recoveryParam: 0,
-        v: 0
+        v: 0,
+        yParityAndS: "0x",
+        compact: "0x"
     };
 
     if (isBytesLike(signature)) {
-        const bytes: Uint8Array = arrayify(signature);
-        if (bytes.length !== 65) {
-            logger.throwArgumentError("invalid signature string; must be 65 bytes", "signature", signature);
-        }
+        let bytes: Uint8Array = arrayify(signature);
 
         // Get the r, s and v
-        result.r = hexlify(bytes.slice(0, 32));
-        result.s = hexlify(bytes.slice(32, 64));
-        result.v = bytes[64];
+        if (bytes.length === 64) {
+            // EIP-2098; pull the v from the top bit of s and clear it
+            result.v = 27 + (bytes[32] >> 7);
+            bytes[32] &= 0x7f;
+
+            result.r = hexlify(bytes.slice(0, 32));
+            result.s = hexlify(bytes.slice(32, 64));
+
+        } else if (bytes.length === 65) {
+            result.r = hexlify(bytes.slice(0, 32));
+            result.s = hexlify(bytes.slice(32, 64));
+            result.v = bytes[64];
+        } else {
+
+            logger.throwArgumentError("invalid signature string", "signature", signature);
+        }
+
 
         // Allow a recid to be used as the v
         if (result.v < 27) {
@@ -448,6 +465,9 @@ export function splitSignature(signature: SignatureLike): Signature {
         }
     }
 
+    result.yParityAndS = result._vs;
+    result.compact = result.r + result.yParityAndS.substring(2);
+
     return result;
 }