/// <summary>
/// Creates a new <see cref="UserKeyAuthorization"/> entry for a user key and a particular archive.
/// </summary>
/// <param name="friendlyName">A friendly name to help the user identify the key.</param>
/// <param name="userKey">The <see cref="UserKey"/> to authorize.</param>
/// <param name="archiveKey">The key used to encrypt the archive that the user key is being authorized for.</param>
/// <param name="securitySettings">The archive's <see cref="SecuritySettings"/>.</param>
/// <returns>The new <see cref="UserKeyAuthorization"/> entry.</returns>
public static UserKeyAuthorization CreateNewAuthorization(
UserKeyAuthorizationParameters newKeyParams,
ReadOnlySpan <byte> keyDerivationSalt,
ArchiveKey archiveKey,
SecuritySettings securitySettings)
{
ArgCheck.IsValid(newKeyParams, nameof(newKeyParams));
ArgCheck.NotEmpty(keyDerivationSalt, nameof(keyDerivationSalt));
ArgCheck.NotNull(archiveKey, nameof(archiveKey));
ArgCheck.IsValid(securitySettings, nameof(securitySettings));
using var userKey = UserKey.DeriveFrom(
newKeyParams.UserSecret,
keyDerivationSalt,
securitySettings);
// The SecureArchive file format requires that the friendly name and keyId be
// checked for tampering when using authenticated cyphers.
var additionalData = Encoding.UTF8.GetBytes(newKeyParams.FriendlyName + userKey.KeyId);
var cryptoStrategy = CryptoHelpers.GetCryptoStrategy(securitySettings.EncryptionAlgo);
var encryptedArchiveKey = userKey.EncryptSecret(cryptoStrategy, archiveKey, additionalData);
return(new UserKeyAuthorization
{
AuthorizationId = Guid.NewGuid(),
FriendlyName = newKeyParams.FriendlyName,
KeyId = userKey.KeyId,
TimeAdded = DateTime.UtcNow,
EncryptedArchiveKey = encryptedArchiveKey,
SecretMetadata = newKeyParams.SecretMetadata,
});
}
/// <summary>
/// Unlocks (i.e. decrypts) the archive with the given raw user secret.
/// </summary>
/// <param name="userSecret">The user secret to use to unlock the archive.</param>
public void Unlock(RawUserSecret userSecret)
{
ArgCheck.NotNull(userSecret, nameof(userSecret));
using var userKey = UserKey.DeriveFrom(
userSecret,
this.ArchiveMetadata.KeyDerivationSalt.ToArray(),
this.ArchiveMetadata.SecuritySettings);
this.Unlock(userKey);
}
