Formusoft.Security 5.1.9

Formusoft.Security

Provides implementations of Formusoft.Security.Abstractions.

Purpose

• implement ISecretProtector
• provide secure storage mechanisms

Default Recommendation

Use ASP.NET Core Data Protection:

services.AddDataProtection();
services.AddScoped<ISecretProtector, DataProtectionSecretProtector>();

Example Implementation

public class DataProtectionSecretProtector : ISecretProtector
{
    private readonly IDataProtector _protector;

    public DataProtectionSecretProtector(IDataProtectionProvider provider)
    {
        _protector = provider.CreateProtector("Formusoft.Security");
    }

    public byte[] Protect(byte[] plaintext)
        => _protector.Protect(plaintext);

    public byte[] Unprotect(byte[] protectedData)
        => _protector.Unprotect(protectedData);
}

Important Notes

• keys must be shared across instances
• configure key persistence properly
• do not lose keys (or data becomes unreadable)

Production Considerations

• use persistent key store (file system, Redis, blob, etc.)
• consider cloud key vaults
• handle key rotation carefully

Security Best Practices

• never store secrets unprotected
• never log sensitive values
• isolate security concerns
• review encryption strategy regularly

Password-hash compatibility limits

Formusoft.Security rejects malformed encoded PBKDF2 and Argon2id hashes before performing unbounded work or allocating unbounded output buffers. Verification keeps bounded compatibility for legacy values generated by earlier deployments, while corrupted or attacker-controlled database values fail safely.

New Argon2id hashes must use 8–256 MiB of memory, 1–20 iterations, 1–16 lanes, 8–64 byte salts, and 16–128 byte outputs. Verification also accepts bounded legacy hashes with at least 8 KiB per lane, 1–64 byte salts, and 4–128 byte outputs; after a successful match, values that differ from the configured policy return SuccessRehashNeeded. PBKDF2 verification accepts at most 1,000,000 iterations, 8–64 byte salts, and 16–128 byte outputs.

Applications should validate these failures like any other failed password verification. Do not reveal whether a stored hash was malformed.

AES-GCM configuration

SecretProtectorOptions.SecretKey must contain exactly 16, 24, or 32 bytes. Configuration now fails when the key is missing or has an invalid AES key length rather than failing later during a request.

TOTP behavior

TOTP verification accepts 6–8 digit codes and periods from 15–300 seconds. Verification compares codes in fixed time, and generated otpauth:// URIs include the normalized algorithm, digit count, and period.

These are defensive implementation changes and do not alter the public service interfaces. A major NuGet version is not required solely for these changes, although release notes should call out the stricter rejection of malformed or unsupported stored values.