How To Encrypt An Encrypted File
Shameka Roessler
When you need to protect the privacy of an email message, encrypt it. Encrypting an email message in Outlook means it's converted from readable plain text into scrambled cipher text. Only the recipient who has the private key that matches the public key used to encrypt the message can decipher the message for reading. Any recipient without the corresponding private key, however, sees indecipherable text. Outlook supports two encryption options:
Microsoft 365 Message Encryption (Information Rights Management) - To use Microsoft 365 Message Encryption, the sender must have Microsoft 365 Message Encryption, which is included in the Office 365 Enterprise E3 license.
IRM protection should not be applied to a message that is already signed or encrypted using S/MIME. To apply IRM protection, S/MIME signature and encryption must be removed from the message. The same applies for IRM-protected messages; users should not sign or encrypt them by using S/MIME.
Before you start this procedure, you must first have added a certificate to the keychain on your computer. Once you have your signing certificate set up on your computer, you'll need to configure it in Outlook.
When you choose to encrypt all outgoing messages by default, you can write and send messages the same as with any other messages, but all potential recipients must have your digital ID to decode or view your messages.
Still, encryption does not prevent ransomware exploits (though it can have the benefit of keeping data from being read and further exploited by ransomware attackers). Files that your organization has already encrypted can just as easily be encrypted (again) by ransomware. This so-called secondary encryption can prove very costly to undo for those who do not understand how to prevent and respond to such scenarios.
There are a number of basic, but necessary steps organizations should take to guard themselves against ransomware attacks. They include installing anti-virus software and firewalls, conducting security awareness training for employees, and maintaining software updates and patches. When it comes to the threat of ransomware encrypting already encrypted files, backup solutions provide a very important alternate access to the corrupted data. Steps include creating an image backup (a single file of the operating system and all associated data) before data encryption and doing frequent backups (either on-premises or in the cloud).
Use Amazon EBS encryption as a straight-forward encryption solution for your EBS resources associated with your EC2 instances. With Amazon EBS encryption, you aren't required to build, maintain, and secure your own key management infrastructure. Amazon EBS encryption uses AWS KMS keys when creating encrypted volumes and snapshots.
Amazon EBS encrypts your volume with a data key using industry-standard AES-256 data encryption. The data key is generated by AWS KMS and then encrypted by AWS KMS with your AWS KMS key prior to being stored with your volume information. All snapshots, and any subsequent volumes created from those snapshots using the same AWS KMS key share the same data key. For more information, see Data keys in the AWS Key Management Service Developer Guide.
Amazon EC2 works with AWS KMS to encrypt and decrypt your EBS volumes in slightly different ways depending on whether the snapshot from which you create an encrypted volume is encrypted or unencrypted.
If the volume is encrypted using the same KMS key as the snapshot, AWS KMS uses the same data key as the snapshot and encrypts it under that same KMS key. If the volume is encrypted using a different KMS key, AWS KMS generates a new data key and encrypts it under the KMS key that you specified. The encrypted data key is sent to Amazon EBS to be stored with the volume metadata.
When a KMS key becomes unusable, the effect is almost immediate (subject to eventual consistency). The key state of the KMS key changes to reflect its new condition, and all requests to use the KMS key in cryptographic operations fail.
When you perform an action that makes the KMS key unusable, there is no immediate effect on the EC2 instance or the attached EBS volumes. Amazon EC2 uses the data key, not the KMS key, to encrypt all disk I/O while the volume is attached to the instance.
However, when the encrypted EBS volume is detached from the EC2 instance, Amazon EBS removes the data key from the Nitro hardware. The next time the encrypted EBS volume is attached to an EC2 instance, the attachment fails, because Amazon EBS cannot use the KMS key to decrypt the volume's encrypted data key. To use the EBS volume again, you must make the KMS key usable again.
If you no longer want access to data stored in an EBS volume encrypted with a data key generated from a KMS key that you intend to make unusable, we recommend that you detach the EBS volume from the EC2 instance before you make the KMS key unusable.
When you encrypt a volume, you can specify the symmetric encryption KMS key to use to encrypt the volume. If you do not specify a KMS key, the KMS key that is used for encryption depends on the encryption state of the source snapshot and its ownership. For more information, see the encryption outcomes table.
If you are using the API or AWS CLI to specify a KMS key, be aware that AWS authenticates the KMS key asynchronously. If you specify a KMS key ID, an alias, or an ARN that is not valid, the action can appear to complete, but it eventually fails.
You cannot change the KMS key that is associated with an existing snapshot or volume. However, you can associate a different KMS key during a snapshot copy operation so that the resulting copied snapshot is encrypted by the new KMS key.
When you create a new, empty EBS volume, you can encrypt it by enabling encryption for the specific volume creation operation. If you enabled EBS encryption by default, the volume is automatically encrypted using your default KMS key for EBS encryption. Alternatively, you can specify a different symmetric encryption KMS key for the specific volume creation operation. The volume is encrypted by the time it is first available, so your data is always secured. For detailed procedures, see Create an Amazon EBS volume.
By default, the KMS key that you selected when creating a volume encrypts the snapshots that you make from the volume and the volumes that you restore from those encrypted snapshots. You cannot remove encryption from an encrypted volume or snapshot, which means that a volume restored from an encrypted snapshot, or a copy of an encrypted snapshot, is always encrypted.
You cannot directly encrypt existing unencrypted volumes or snapshots. However, you can create encrypted volumes or snapshots from unencrypted volumes or snapshots. If you enable encryption by default, Amazon EBS automatically encrypts new volumes and snapshots using your default KMS key for EBS encryption. Otherwise, you can enable encryption when you create an individual volume or snapshot, using either the default KMS key for Amazon EBS encryption or a symmetric customer managed encryption key. For more information, see Create an Amazon EBS volume and Copy an Amazon EBS snapshot.
You can also apply new encryption states when launching an instance from an EBS-backed AMI. This is because EBS-backed AMIs include snapshots of EBS volumes that can be encrypted as described. For more information, see Use encryption with EBS-backed AMIs.
To create new cryptographic material for use with Amazon EBS encryption, you can either create a new customer managed key, and then change your applications to use that new KMS key. Or, you can enable automatic key rotation for an existing customer managed key.
When you enable automatic key rotation for a customer managed key, AWS KMS generates new cryptographic material for the KMS key every year. AWS KMS saves all previous versions of the cryptographic material so that you can continue to decrypt and use volumes and snapshots previously encrypted with that KMS key material. AWS KMS does not delete any rotated key material until you delete the KMS key.
When you use a rotated customer managed key to encrypt a new volume or snapshot, AWS KMS uses the current (new) key material. When you use a rotated customer managed key to decrypt a volume or snapshot, AWS KMS uses the version of the cryptographic material that was used to encrypt it. If a volume or snapshot is encrypted with a previous version of the cryptographic material, AWS KMS continues to use that previous version to decrypt it. AWS KMS does not re-encrypt previously encrypted volumes or snapshots to use the new cryptographic material after a key rotation. They remain encrypted with the cryptographic material with which they were originally encrypted. You can safely use a rotated customer managed key in applications and AWS services without code changes.
Amazon RDS encrypted DB instances use the industry standard AES-256 encryption algorithm to encrypt your data on the server that hosts your Amazon RDS DB instances. After your data is encrypted, Amazon RDS handles authentication of access and decryption of your data transparently with a minimal impact on performance. You don't need to modify your database client applications to use encryption.
Amazon RDS encrypted DB instances provide an additional layer of data protection by securing your data from unauthorized access to the underlying storage. You can use Amazon RDS encryption to increase data protection of your applications deployed in the cloud, and to fulfill compliance requirements for encryption at rest.
For an Amazon RDS encrypted DB instance, all logs, backups, and snapshots are encrypted. Amazon RDS uses an AWS Key Management Service key to encrypt these resources. For more information about KMS keys, see AWS KMS keys in the AWS Key Management Service Developer Guide and AWS KMS key management. If you copy an encrypted snapshot, you can use a different KMS key to encrypt the target snapshot than the one that was used to encrypt the source snapshot.
4a15465005