> For the complete documentation index, see [llms.txt](https://polarischain-1.gitbook.io/polarischain/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://polarischain-1.gitbook.io/polarischain/4.-cryptographic-foundations-and-compliance-framework/4.1-quantum-threat-model-and-cryptographic-posture.md).

# 4.1 - Quantum Threat Model & Cryptographic Posture

Polarischain’s cryptographic design assumes a future adversary with access to a **Cryptographically Relevant Quantum Computer (CRQC)** capable of executing Shor’s and Grover’s algorithms at scale. The protocol eliminates all classical asymmetric cryptography, replacing it with post-quantum primitives that meet or exceed NIST security thresholds.

| Attack Vector           | Classical Impact        | Quantum Impact                 | Polarischain Defense                          |
| ----------------------- | ----------------------- | ------------------------------ | --------------------------------------------- |
| Shor’s on ECDSA/Ed25519 | N/A                     | Complete signature forgery     | Not used — Dilithium replaces all ECC         |
| Shor’s on RSA           | N/A                     | Complete decryption/forgery    | Not used anywhere in stack                    |
| Shor’s on classical KEX | N/A                     | Decrypt any recorded session   | ML-KEM-768 replaces all classical KEX         |
| Grover’s on SHA-256     | N/A                     | Halves security (256→128 bits) | BLAKE2b-256 provides 128-bit PQ security      |
| Grover’s on AES-256     | N/A                     | Halves security (256→128 bits) | 128-bit PQ security meets financial standards |
| Classical brute force   | Infeasible at ≥128 bits | N/A                            | All primitives ≥128-bit classical baseline    |


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