fix(Base58): preserve leading zeros for zero-valued and empty inputs

src/core/Base58.ts

@@ -125,8 +125,9 @@ export function toHex(value: string): Hex.Hex {
     integer = integer + internal.alphabetToInteger[char]!
   }
 
-  if (!pad) return `0x${integer.toString(16)}` as Hex.Hex
-  return `0x${'0'.repeat(pad * 2)}${integer.toString(16)}` as Hex.Hex
+  const body = integer === 0n ? '' : integer.toString(16)
+  if (!pad) return `0x${body}` as Hex.Hex
+  return `0x${'0'.repeat(pad * 2)}${body}` as Hex.Hex
 }
 
 export declare namespace toHex {

src/core/_test/Base58.test.ts

@@ -17,6 +17,16 @@ describe('fromHex', () => {
   test('default', () => {
     expect(Base58.fromHex('0x00000000287fb4cd')).toBe('1111233QC4')
   })
+
+  test('leading zeros (all-zero value)', () => {
+    expect(Base58.fromHex('0x00')).toBe('1')
+    expect(Base58.fromHex('0x0000')).toBe('11')
+    expect(Base58.fromHex('0x000000')).toBe('111')
+  })
+
+  test('empty', () => {
+    expect(Base58.fromHex('0x')).toBe('')
+  })
 })
 
 describe('fromString', () => {
@@ -47,6 +57,15 @@ describe('toBytes', () => {
       ]
     `)
   })
+
+  test('leading zeros', () => {
+    expect(Base58.toBytes('1')).toStrictEqual(new Uint8Array([0]))
+    expect(Base58.toBytes('1112NEpo7TZRRrLZSi2U')).toStrictEqual(
+      new Uint8Array([
+        0, 0, 0, 72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100, 33,
+      ]),
+    )
+  })
 })
 
 describe('toHex', () => {
@@ -57,6 +76,16 @@ describe('toHex', () => {
       '[Error: invalid base58 character: I]',
     )
   })
+
+  test('leading ones (all-zero value)', () => {
+    expect(Base58.toHex('1')).toBe('0x00')
+    expect(Base58.toHex('11')).toBe('0x0000')
+    expect(Base58.toHex('111')).toBe('0x000000')
+  })
+
+  test('empty', () => {
+    expect(Base58.toHex('')).toBe('0x')
+  })
 })
 
 describe('toString', () => {

src/core/internal/base58.ts

@@ -77,6 +77,7 @@ export function from(value: Hex.Hex | Bytes.Bytes) {
   let integer = (() => {
     let hex = value
     if (value instanceof Uint8Array) hex = Hex.fromBytes(bytes)
+    if (hex === '0x') return 0n
     return BigInt(hex as string)
   })()
 
@@ -87,7 +88,7 @@ export function from(value: Hex.Hex | Bytes.Bytes) {
     result = integerToAlphabet[remainder] + result
   }
 
-  while (bytes.length > 1 && bytes[0] === 0) {
+  while (bytes.length > 0 && bytes[0] === 0) {
     result = '1' + result
     bytes = bytes.slice(1)
   }