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Image MIME Reference
Sealed-PNG

SealedMedia Portable Network Graphics

image/vnd.sealed.png
VS

Extended Image File Format

image/vnd.xiff
XIFF

A complete technical comparison of SealedMedia Portable Network Graphics and Extended Image File Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Sealed-PNG XIFF
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
SealedMedia Portable Network Graphics
image/vnd.sealed.png
Extension
.spng.sealed-png
Container SealedMedia / Oracle IRM Wrapper
Compression Encrypted Payload (Deflate)
Algorithm
AES EncryptionDeflate (Internal PNG payload)
Color Depth Encrypted Payload
Developed by SealedMedia (Acquired by Oracle Corporation)
Released Late 1990s / Early 2000s
Magic Bytes
Unknown (Proprietary SealedMedia Container)
Full Sealed-PNG reference →
Extended Image File Format
image/vnd.xiff
Extension
.xif
Container TIFF-based Proprietary Container
Compression CCITT Group 3 / Group 4 / LZW / Uncompressed
Algorithm
CCITT Group 4LZWNone
Color Depth 1-bit (Monochrome), 8-bit (Grayscale), 24-bit (RGB)
Developed by Keyfile Corporation
Released 1994
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Full XIFF reference →

Browser Support Comparison

Browser Sealed-PNG XIFF
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Sealed-PNG

Sealed-PNG Strengths

  • Provided absolute control over intellectual property, allowing enterprise administrators to instantly revoke viewing rights of a local file globally
  • Detailed audit trails tracked exactly who opened the image, when, and from what IP address
Limitations
  • Completely proprietary and relies on a central authentication server; if the server goes offline, the image is permanently inaccessible
  • No support in modern operating systems, web browsers, or standard image editing software without installing heavy enterprise DRM clients
  • Oracle effectively deprecated the IRM product line, leaving legacy sealed documents difficult to recover
XIFF

XIFF Strengths

  • Pioneered early enterprise document workflow integration by binding administrative routing data directly to the document image file
  • Leveraged efficient fax compression standards to keep storage requirements low on 1990s server infrastructure
Limitations
  • Completely proprietary and obsolete; Keyfile Corporation's software ecosystem no longer exists
  • Causes widespread MIME type identification conflicts due to sharing the exact same binary header signature as standard TIFF files
  • Zero support in modern operating systems or web browsers

When to choose which format

Sealed-PNG
Use Sealed-PNG when…
  • Enterprise Information Rights Management (IRM)
  • Secure Corporate Intellectual Property Distribution
  • Revocable Medical or Legal Imaging
XIFF
Use XIFF when…
  • Keyfile Enterprise Document Management
  • Legacy Corporate Workflow Archival
  • Scanned Multi-page Document Routing

More comparisons

Sealed-PNG vs ACES → XIFF vs ACES → Sealed-PNG vs APNG → XIFF vs APNG → Sealed-PNG vs AVCI → XIFF vs AVCI → Sealed-PNG vs AVCS → XIFF vs AVCS → Sealed-PNG vs AVIF → XIFF vs AVIF → All comparisons →
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