Bitstring Status List

The Bitstring Status List is a privacy-preserving mechanism for publishing status information about Verifiable Credentials, designed to be space-efficient and high-performance. It enables issuers to manage credential statuses like suspension and revocation through compressed bitstrings while maintaining privacy and scalability.

Key differentiating features:

• Privacy-preserving group status updates
• Highly compressible format (>90% compression in typical cases)
• Minimal bandwidth requirements
• Content Distribution Network (CDN) compatible
• No false positives
• Supports multiple status types per credential

Purpose and Scope:

• Provides a standardized way to track credential status changes
• Enables privacy-preserving status checks without individual credential tracking
• Supports multiple status types including revocation, suspension, and refresh
• Minimum list size of 131,072 entries for adequate privacy protection

Key Technical Specifications:

• Uses BitstringStatusListEntry and BitstringStatusListCredential data models
• Status information encoded as compressed bitstrings using GZIP
• Each credential mapped to specific bit position via statusListIndex
• Supports multiple status purposes in single list
• Uses base64url encoding (no padding) for compressed data

Implementation Requirements:

• Must implement Generate and Validate algorithms
• Must support minimum bitstring length of 16KB
• Must use proper bit ordering (left-to-right indexing)
• Must implement proper error handling for malformed values
• Must support application/vc media type

Security Considerations:

• Proper bitstring encoding/decoding is critical
• Implementers must carefully manage validity periods
• Caching recommendations for privacy protection
• Protection against correlation attacks
• Careful management of global identifiers

Interoperability Features:

• Compatible with W3C Verifiable Credentials standard
• Supports multiple proof formats
• Can be used with various transport protocols
• Supports content negotiation
• Enables credential stapling

Current Adoption Status:

• W3C Candidate Recommendation Draft as of February 2025
• Implemented by multiple digital credential platforms
• Supported by major credential verifier implementations
• Used in production systems for credential status management