Statement of Applicability — Use of Cryptography
Status: draft for control-owner review. TBC means that the implementation or evidence must be confirmed before approval. This document must describe controls that actually operate; material TBC items may not be treated as implemented.
| Field |
Value |
| Document ID |
[e.g. ISMS-SOA-08.24] |
| Version |
[0.1 — draft] |
| Classification |
[Internal] |
| Document owner |
[IS Manager] |
| Approved by |
[name / role] on [date] |
| Scope entities |
[Ahola Group entities in scope] |
| Review cycle |
[Annually, and on material change to the cryptographic estate] |
| Next review |
[date] |
1. Purpose
This document states which cryptographic controls apply to Ahola Digital, how they are implemented, who owns them, and what evidence demonstrates that they operate. It is the controlling statement for ISO/IEC 27001:2022 Annex A control 8.24, Use of cryptography, and supports the obligations in section 3.
Cryptography is used to protect the confidentiality, integrity and authenticity of information in transit and at rest. This document also establishes minimum requirements for certificate, password and secret management.
2. Scope
| Dimension |
In scope |
Out of scope (and why) |
| Information systems |
[e.g. all production and corporate systems] |
[…] |
| Environments |
[production / staging / development] |
[…] |
| Locations & platforms |
[e.g. on-prem hypervisors, cloud IaaS, SaaS, endpoints] |
[…] |
| Data classifications |
[e.g. Confidential and above; personal data of any class] |
[…] |
| Third parties |
[processors handling in-scope data] |
[…] |
3. Regulatory and standard drivers
| Driver |
Requirement (summary) |
Where addressed |
| ISO/IEC 27001:2022 A.8.24 |
Rules for effective use of cryptography, including key management |
This document |
| ISO/IEC 27001:2022 A.5.31 |
Legal, statutory and contractual requirements, incl. any national restrictions on cryptography |
§3 note, §11 |
| GDPR Art. 32(1)(a) |
Encryption of personal data as an appropriate technical measure |
§7 rows for personal-data systems |
| GDPR Art. 34(3)(a) |
Encryption may remove the obligation to notify data subjects of a breach |
§7, §12 |
| NIS2 Art. 21(2)(h) |
Policies and procedures on the use of cryptography and, where appropriate, encryption |
This document |
[Customer / contractual] |
[e.g. specific TLS or key-length obligations in customer contracts] |
[…] |
[Other] |
[…] |
[…] |
Note on legal restrictions: [state whether any jurisdiction in which the organisation operates restricts the import, export, or use of cryptography, or mandates lawful-access provisions. If none apply, say so explicitly.]
4. Roles and responsibilities
| Role |
Responsibility |
| ISMS Manager / IT Manager (TBC) |
Owns this document, approves the cryptographic standard and coordinates exceptions |
| DevOps / infrastructure team |
Implements controls; maintains certificate, key and secret inventories; responds to alerts |
| Data Protection Officer / Compliance Manager |
Reviews controls for personal-data processing and DPIA linkage |
| System and service owners |
Apply the standard, retain evidence, review access and raise exceptions |
| Key custodians |
Recover or administer high-impact root, recovery and master keys under separated duties; named custodians TBC |
| Users |
Store organization credentials only in the approved password manager and report suspected compromise immediately |
| Internal / external audit |
Tests control design and operating effectiveness against section 12 |
5. Approved algorithms and minimum parameters
| Purpose |
Approved algorithm(s) |
Minimum key / parameter |
Notes |
| Symmetric encryption |
[e.g. AES-GCM, ChaCha20-Poly1305] |
[256-bit] |
[AEAD modes required] |
| Asymmetric encryption / key exchange |
[e.g. ECDH P-256/P-384, X25519, RSA-OAEP] |
[RSA ≥ 3072; EC ≥ 256] |
[…] |
| Digital signatures |
[e.g. ECDSA P-256, Ed25519, RSA-PSS] |
[…] |
[…] |
| Hashing |
[e.g. SHA-256, SHA-384, SHA-3] |
[≥ 256-bit output] |
[…] |
| Password / credential storage |
[e.g. Argon2id, scrypt, bcrypt] |
[state work factors] |
[…] |
| Transport |
[TLS 1.3; TLS 1.2 with AEAD ciphers only] |
[…] |
[cipher suite allowlist: reference or attach] |
| VPN / tunnelling |
[e.g. WireGuard, IKEv2/IPsec] |
[…] |
[…] |
| Random number generation |
[OS CSPRNG / HSM] |
— |
[no application-level custom RNG] |
| Full-disk encryption |
[…] |
[…] |
[recovery key escrow location] |
Authoritative reference used: [e.g. BSI TR-02102, NIST SP 800-131A Rev.3, SOG-IS agreed mechanisms, Traficom/NCSC-FI guidance] — cite one so algorithm choices are defensible rather than opinion.
6. Prohibited and deprecated use
| Prohibited / deprecated |
Status |
Remediation deadline |
Owner |
| SSL 2.0/3.0, TLS 1.0/1.1 |
[Prohibited] |
[…] |
[…] |
| MD5, SHA-1 (signatures) |
[Prohibited] |
[…] |
[…] |
| DES, 3DES, RC4, Blowfish |
[Prohibited] |
[…] |
[…] |
| RSA < 2048-bit |
[Prohibited] |
[…] |
[…] |
| ECB mode, unauthenticated CBC |
[Prohibited] |
[…] |
[…] |
Self-signed certificates on [internal services] |
[Deprecated / exception required] |
[…] |
[…] |
[Legacy system X using …] |
[Exception — see §11] |
[…] |
[…] |
7. Applicability statement
The core table. For each use case: is cryptography applied, by what mechanism, who holds the key, and what proves it.
| # |
Use case |
Applicable? |
Mechanism / technology |
Key holder & storage |
Justification or exclusion rationale |
Evidence ref. |
| 7.1 |
Endpoint disk encryption |
[Yes] |
[…] |
[…] |
[Loss/theft of mobile devices; GDPR Art. 32] |
[…] |
| 7.2 |
Server / VM volume encryption |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.3 |
Backup encryption (on-site) |
[…] |
[client-side vs. at-rest — state which] |
[…] |
[…] |
[…] |
| 7.4 |
Backup encryption (off-site / object storage) |
[…] |
[…] |
[…] |
[key must not be recoverable only from the encrypted set] |
[…] |
| 7.5 |
Database encryption at rest |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.6 |
Field / column-level encryption of personal data |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.7 |
Removable media |
[…] |
[…] |
[…] |
[or: prohibited by policy — reference it] |
[…] |
| 7.8 |
Public-facing services in transit |
[…] |
[TLS version + HSTS] |
[…] |
[…] |
[…] |
| 7.9 |
Internal / east-west traffic |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.10 |
Site-to-site and remote access |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.11 |
Administrative access (SSH / RDP / management planes) |
[…] |
[key types, MFA binding] |
[…] |
[…] |
[…] |
| 7.12 |
Email in transit |
[…] |
[MTA-STS, DANE, opportunistic TLS] |
— |
[…] |
[…] |
| 7.13 |
Email / file end-to-end encryption |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.14 |
Managed file transfer / EDI with partners |
[…] |
[…] |
[…] |
[per-partner requirements] |
[…] |
| 7.15 |
Secrets, credentials and API keys |
[…] |
[secret manager; envelope encryption] |
[…] |
[…] |
[…] |
| 7.16 |
Password / authenticator storage |
[…] |
[…] |
— |
[…] |
[…] |
| 7.17 |
Code, artifact and container image signing |
[…] |
[…] |
[…] |
[supply-chain integrity] |
[…] |
| 7.18 |
Log and audit-trail integrity |
[…] |
[…] |
[…] |
[…] |
[…] |
| 7.19 |
Pseudonymisation / tokenisation of personal data |
[…] |
[…] |
[…] |
[GDPR Art. 25, Art. 32] |
[…] |
| 7.20 |
SaaS / third-party held data |
[…] |
[provider-managed vs. customer-managed keys] |
[…] |
[record in DPA / vendor register] |
[…] |
| 7.21 |
[…] |
[…] |
[…] |
[…] |
[…] |
[…] |
8. Key management lifecycle
| Stage |
Procedure |
Owner |
Frequency / trigger |
Evidence |
| Generation |
[where, by what, entropy source; dual control for root keys] |
[…] |
[…] |
[…] |
| Distribution |
[…] |
[…] |
[…] |
[…] |
| Storage & protection |
[HSM / KMS / secret manager; never in code or config repos] |
[…] |
— |
[…] |
| Access control |
[who can read, who can only use; separation of duties] |
[…] |
— |
[…] |
| Rotation |
[per key class — state intervals] |
[…] |
[…] |
[…] |
| Escrow / recovery |
[custodians, split knowledge, where the recovery material physically lives] |
[…] |
[test annually] |
[…] |
| Compromise response |
[revoke, re-key, re-encrypt; link to incident process] |
[…] |
[on suspicion] |
[…] |
| Retirement & destruction |
[crypto-erase, verified destruction, retention of keys needed for archived data] |
[…] |
[…] |
[…] |
Key inventory: maintained at [location], listing key ID, purpose, algorithm, owner, creation date, rotation due, system(s) served.
9. Certificate management
| Item |
Detail |
| Public CA(s) used |
DVV |
| Internal CA |
[yes; root protection] |
| Issuance method |
[ACME with DNS-01 validation] |
| Storage / distribution |
[…] |
| Maximum validity |
[…] |
| Expiry monitoring & alerting |
[tool, threshold, who is paged] |
| Certificate inventory |
[location] |
| Revocation procedure |
[…] |
10. Crypto-agility and post-quantum readiness
| Question |
Answer |
| Can algorithms be changed without redesigning the system? |
[per system class] |
| Is there an inventory of where each algorithm is used? |
[…] |
| Data with confidentiality lifetime beyond ~2035 (harvest-now-decrypt-later exposure) |
[identify it] |
| PQC migration position |
[e.g. monitoring; hybrid X25519-MLKEM768 adopted where vendor-supported] |
| Owner and review date |
[…] |
11. Exceptions
| ID |
System / control deviated from |
Reason |
Compensating control |
Risk accepted by |
Expiry / review |
[EX-01] |
[…] |
[…] |
[…] |
[…] |
[…] |
Exceptions require [approver role] approval, a compensating control, and an expiry date. No open-ended exceptions.
12. Monitoring, evidence and verification
| Verification activity |
Method |
Frequency |
Owner |
Evidence location |
| TLS configuration scan of external services |
[…] |
[…] |
[…] |
[…] |
| Disk-encryption compliance across the estate |
[…] |
[…] |
[…] |
[…] |
| Backup restore test including key recovery |
[…] |
[…] |
[…] |
[…] |
| Certificate expiry and inventory reconciliation |
[…] |
[…] |
[…] |
[…] |
| Key rotation adherence |
[…] |
[…] |
[…] |
[…] |
| Prohibited-algorithm detection |
[…] |
[…] |
[…] |
[…] |
| Third-party crypto attestation review |
[…] |
[…] |
[…] |
[…] |
| Document |
Reference |
| Information Security Policy |
[…] |
| Access Control Policy |
[…] |
| Backup and Recovery Policy |
[…] |
| Secure Development Policy |
[…] |
| Supplier Security / DPA register |
[…] |
| Incident Response Plan |
[…] |
| Risk register entries |
[IDs] |
14. Version history
| Version |
Date |
Author |
Change |
[0.1] |
[…] |
[…] |
Initial draft |