> ## Documentation Index
> Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt
> Use this file to discover all available pages before exploring further.

# Blob.isValidVersion

> Validate versioned hash format and version byte

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## Validation Rules

A valid versioned hash must:

1. Be exactly 32 bytes
2. Have version byte 0x01 (KZG commitment version)

```typescript theme={null}
import { Blob } from 'tevm';

function isValidVersionedHash(hash: Uint8Array): boolean {
  // Check length
  if (hash.length !== 32) {
    return false;
  }

  // Check version byte
  if (hash[0] !== 0x01) {
    return false;
  }

  return true;
}

// Equivalent to Blob.isValidVersion()
```

## Version Byte

Current supported version:

```typescript theme={null}
import { Blob } from 'tevm';

console.log(Blob.COMMITMENT_VERSION_KZG); // 0x01

const hash = blob.toVersionedHash();
console.log(hash[0]); // 0x01

// Future versions (not yet supported)
// 0x02 = Future commitment scheme
// 0x03 = Another scheme
```

## VersionedHash Utilities

```typescript theme={null}
import { Blob } from 'tevm';

const versionedHash = blob.toVersionedHash();

// Validate format
console.log(Blob.isValidVersion(versionedHash)); // true

// Check specific validation using VersionedHash namespace
console.log(Blob.VersionedHash.isValid(versionedHash)); // true

// Get version byte
const version = Blob.VersionedHash.getVersion(versionedHash);
console.log(version); // 1

// Alternative: version() method
console.log(Blob.VersionedHash.version(versionedHash)); // 1
```

## Transaction Validation

```typescript theme={null}
import { Blob } from 'tevm';

function validateBlobVersionedHashes(
  hashes: Uint8Array[],
  maxBlobs: number = Blob.MAX_PER_TRANSACTION
): boolean {
  // Check count
  if (hashes.length === 0 || hashes.length > maxBlobs) {
    return false;
  }

  // Validate each hash
  for (const hash of hashes) {
    if (!Blob.isValidVersion(hash)) {
      return false;
    }
  }

  return true;
}

// Usage
const tx = { blobVersionedHashes: [hash1, hash2, hash3] };
if (!validateBlobVersionedHashes(tx.blobVersionedHashes)) {
  throw new Error('Invalid versioned hashes');
}
```

## Error Cases

```typescript theme={null}
import { Blob } from 'tevm';

// Wrong length
const tooShort = Bytes16();
console.log(Blob.isValidVersion(tooShort)); // false

const tooLong = Bytes64();
console.log(Blob.isValidVersion(tooLong)); // false

// Wrong version
const wrongVersion = Bytes32();
wrongVersion[0] = 0x02; // Unsupported
console.log(Blob.isValidVersion(wrongVersion)); // false

wrongVersion[0] = 0x00; // Invalid
console.log(Blob.isValidVersion(wrongVersion)); // false

// Correct
const correct = Bytes32();
correct[0] = 0x01; // KZG version
console.log(Blob.isValidVersion(correct)); // true
```

## See Also

* [toVersionedHash](./toVersionedHash) - Compute versioned hash
* [versioned-hash](./versioned-hash) - VersionedHash namespace utilities
* [EIP-4844](/primitives/blob/eip4844) - Versioned hash specification