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Recommend AEAD encryption algorithms

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Raja Grewal 2023-06-07 23:04:36 +10:00
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content/posts/knowledge/Mobile Verification Toolkit for Android and iOS.md
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@ -1,6 +1,6 @@
--- ---
title: "Mobile Verification Toolkit for Android and iOS" title: "Mobile Verification Toolkit for Android and iOS"
date: 2023-05-16 date: 2023-06-07
tags: ['Knowledge base', 'Privacy', 'Security', 'Android', 'iOS'] tags: ['Knowledge base', 'Privacy', 'Security', 'Android', 'iOS']
author: Raja Grewal author: Raja Grewal
--- ---
@ -49,17 +49,15 @@ Overall, the disclaimer is more than reasonable since on the balance of probabil
Therefore we highlight a few strict requirements prior to using `mvt`. First ensure you have full control over the desktop/laptop used to conduct the scan, do not use shared or work computers. The desktop/laptop operating system must also be hardened as much as feasibly possible. Therefore we highlight a few strict requirements prior to using `mvt`. First ensure you have full control over the desktop/laptop used to conduct the scan, do not use shared or work computers. The desktop/laptop operating system must also be hardened as much as feasibly possible.
Next, for transferring internal mobile device content, ensure the data is only ever copied to encrypted storage media. Never under any situation use a unencrypted device to store and analyse the mobile device data since data recovery of ‘deleted’ files is very mature profession [[1b](https://en.wikipedia.org/wiki/Data_recovery), [2b](https://en.wikipedia.org/wiki/Data_erasure), [3b](https://docs.bleachbit.org/doc/shred-files-and-wipe-disks.html)]. Next, for transferring internal mobile device content, ensure the data is only ever copied to encrypted storage media. Never under any situation use a unencrypted device to store and analyse the mobile device data since data recovery of ‘deleted’ files is very mature profession [[1b](https://en.wikipedia.org/wiki/Data_recovery), [2b](https://en.wikipedia.org/wiki/Data_erasure), [3b](https://docs.bleachbit.org/doc/shred-files-and-wipe-disks.html)]. For maximum security, we advise strictly only the use of encryption schemes that incorporate AEAD ciphers [[1c](https://en.wikipedia.org/wiki/Authenticated_encryption), [2c](https://www.rfc-editor.org/rfc/rfc5116), [3c](https://datatracker.ietf.org/doc/html/draft-mcgrew-aead-aes-cbc-hmac-sha2-01), [4c](https://www.cryptosys.net/manapi/api_aeadalgorithms.html)]. One example on [Linux](https://gitlab.com/cryptsetup/cryptsetup/-/wikis/DMCrypt) is using `dm-crypt` with the `--integrity` option.
For maximum privacy the author advises the use of [VeraCrypt](https://www.veracrypt.fr/en/Home.html) volumes as these enable robust cross-platform compatibility allowing the seamless construction of containers with predetermined size using unmodified existing desktop OS installations. Additionally, while there are countless alternatives methods to securely store data such as other disk encryption software or even the use of RAM disks, we ultimately leave this decision to the reader. Regarding the recommendation of VeraCrypt, there exists substantial evidence from very experienced and well-established ([nation-state-sponsored](https://www.elcomsoft.com/company.html)) practitioners [[1c](https://blog.elcomsoft.com/2020/01/a-comprehensive-guide-on-securing-your-system-archives-and-documents/), [2c](https://blog.elcomsoft.com/2020/03/breaking-veracrypt-containers/), [3c](https://blog.elcomsoft.com/2021/06/breaking-veracrypt-obtaining-and-extracting-on-the-fly-encryption-keys/)] detailing its strengths (despite some theoretical limitations discussed across various online forum threads). In short, the 75 possible unique combinations of [symmetric encryption algorithms](https://www.veracrypt.fr/en/Encryption%20Algorithms.html) and [hashing algorithms](https://www.veracrypt.fr/en/Hash%20Algorithms.html) (without either of their respective specifics being stored in the disk header), variable [PIM](https://www.veracrypt.fr/en/Personal%20Iterations%20Multiplier%20(PIM).html) selection, and also the ability to create [hidden volumes](https://www.veracrypt.fr/en/Hidden%20Volume.html) are only some of the reasons that make VeraCrypt a good default choice. Upon selection of a suitable encryption algorithm, simply create a new volume prior to a scan and only use this volume for all `mvt` related data. For typical devices the required volume size for `mvt` outputs depends on the length of history of the device, allocating 1GB should generally be more than sufficient for most cases involving Android devices. For iOS/iPadOS devices, since the entire contents of the devices must also be transferred, allocated volume size must be sufficiently greater than double the size of the all data stored on the mobile devices.
If using VeraCrypt, simply create a new volume prior to a scan and only use this volume for all `mvt` related data. For typical devices the required VeraCrypt volume size for `mvt` outputs depends on the length of history of the device, allocating 1GB should generally be more than sufficient for most cases involving Android devices. For iOS/iPadOS devices, since the entire contents of the devices must also be transferred, allocated volume size must be sufficiently greater than double the size of the all data stored on the mobile devices. Upon completion of the scans, there are two paths one may take if no intrusions are detected. The first involves simply dismounting and deleting the volume which will assist in preventing forensic data recovery. The second involves retaining `mvt` outputs and other desirable data and transferring them to other similarly secure storage media for logging purposes. In the unlikely event intrusions are detected, you should retain all associated evidence and (ideally) must cease using the device.
Upon completion of the scans, there are two paths one may take if no intrusions are detected. The first involves simply dismounting and deleting the VeraCrypt volume which will assist in preventing forensic data recovery. The second involves retaining `mvt` outputs and other desirable data and transferring them to other similarly secure storage media for logging purposes. In the unlikely event intrusions are detected, you should retain all associated evidence and (ideally) must cease using the device.
To emphasise again, extreme care must be taken with the handling and storage of all `mvt` related data. Any leak of this data would be very dangerous as it provides extraordinary amounts of detail regarding the internal contents of the mobile device, the overwhelming of which is even impossible to access on-device. To emphasise again, extreme care must be taken with the handling and storage of all `mvt` related data. Any leak of this data would be very dangerous as it provides extraordinary amounts of detail regarding the internal contents of the mobile device, the overwhelming of which is even impossible to access on-device.
If you are using `mvt` purely due to a mixture of paranoia and curiosity, after confirming the presence of no malicious indicators, do not retain any scan logs and delete the VeraCrypt volume. For high-risk individuals, retaining periodic scan logs can be beneficial but must be done with appropriately great care. If you are using `mvt` purely due to a mixture of paranoia and curiosity, after confirming the presence of no malicious indicators, do not retain any scan logs and delete the relevant storage volumes. For high-risk individuals, retaining periodic scan logs can be beneficial but must be done with appropriately great care.
## Limitations ## Limitations