Technical Paper: The SACD Ripper – Methodology, Forensic Analysis, and Audio Preservation Abstract The Super Audio CD (SACD) represents a high-resolution audio format that has resisted digital extraction for nearly two decades due to physical encryption (Pit Signal Processing/PSP) and logical encryption (CPPM/Watermarking). This paper details the SACD Ripper suite (sacd_extract, ISO2DSD), its exploitation of legacy hardware (e.g., PlayStation 3), the forensic extraction pipeline, and its implications for audio preservation. 1. Introduction SACD was introduced in 1999 by Sony and Philips as the successor to the CD, offering:
DSD64 (1-bit, 2.8224 MHz) – 64 times CD sampling rate. Multi-channel (up to 5.1) and stereo layers. Physical encryption – The HD layer is scrambled with a key derived from the disc’s physical pit geometry (PSP).
For over a decade, no public method existed to rip SACDs. The 2011 fail0verflow exploit on the PlayStation 3 (PS3) changed this: the PS3’s decryption keys were extracted, enabling raw DSD stream access. 2. The SACD Structure An SACD contains up to three zones: | Zone | Content | Encryption | |------|---------|-------------| | CD Layer (Red Book) | 16-bit/44.1 kHz | None | | HD Stereo | DSD64 stereo | PSP + CPPM | | HD Multi-channel | DSD64 5.1 | PSP + CPPM | CPPM (Content Protection for Prerecorded Media) – A variant of AES-128 with a Media Key Block (MKB). Watermark – An inaudible pattern in analog output; ripping bypasses this. 3. The SACD Ripper Ecosystem 3.1 Critical Hardware The only widely exploited device is the PlayStation 3 :
Model: CECH-20xx, CECH-21xx, CECH-25xx (with firmware 3.55 or lower). Mechanism: OtherOS feature removed after FW 3.21; custom firmware (CFW) reinstates hypervisor access. Process: CFW → Install sacd-ripper.pkg → Mount disc → Dump ISO or extract DSDIFF/DSF. sacd ripper
3.2 Software Components | Tool | Function | |-------|----------| | sacd_extract | Core extraction engine; reads DSD frames, strips CPPM. | | ISO2DSD | GUI wrapper (macOS/Windows) that calls sacd_extract . | | sacd_gui | Java-based cross-platform GUI. | 4. Extraction Workflow [SACD Disc] → (PS3 BD Drive) → (CFW + sacd_ripper) → (RAM decryption) → (USB/Network) → ISO/DSF
Step-by-step:
Disc authentication – PS3 BD drive reads MKB, authenticates with player keys. Title key derivation – Using stored device keys + MKB → decrypt title-specific key. Sector decryption – AES-128-CTR mode decrypts DSD frames on-the-fly. Output options : Technical Paper: The SACD Ripper – Methodology, Forensic
ISO – Raw decrypted sector image (includes both stereo & multi-channel). DSDIFF (DFF) – Philips DSDIFF container, 1-bit per channel. DSF – Sony’s DSF container (supports metadata, easier for tagging). DST decompression – DST (Direct Stream Transfer) is lossless compression; sacd_extract can decompress to raw DSD.
5. Technical Challenges & Solutions 5.1 DST Decompression Many multi-channel SACDs use DST to fit 5.1 DSD64 into the same area as stereo. sacd_extract implements a DST decoder (based on reverse-engineered Philips code). Decompressed DSD is 1/8th of DST size. 5.2 Frame Integrity SACD frames contain 16 DSD blocks (each 4096 bits → 512 bytes). The ripper validates CRC32 of each frame; corrupted sectors are re-read up to 3 times. 5.3 Watermark Handling The PS3’s analog watermark detector is not triggered during digital extraction. The ripped DSD contains the original unwatermarked bitstream. 6. Forensic Integrity & Verification To guarantee a perfect rip, the community recommends:
Compare multiple rips from different PS3s. Generate checksums (MD5/SHA256) of the decrypted ISO. Use sacd_extract -m to extract a metadata report (TOC, DST flags, channel counts). Introduction SACD was introduced in 1999 by Sony
Example verification: sacd_extract -i 192.168.1.10:2002 -P -v
This queries the PS3’s ripper daemon and validates sector-by-sector. 7. Legal & Ethical Considerations | Jurisdiction | Ripping for personal backup | |--------------|-----------------------------| | USA (DMCA 1201) | Prohibits circumvention of access controls (CPPM/PSP). | | EU (Infosoc Directive) | Allows backup copies if no effective technological measures are broken. | | Japan (Copyright Law) | Explicitly forbids SACD ripping. | Practical stance: Most users who rip SACDs own the physical disc and argue fair use for format shifting. However, distribution of extracted DSD files is clearly infringing. 8. Performance & Quality Metrics