Merge pull request #1286 from Granddave/feature/update-vault-docs

Update vault documentation
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@ -14,8 +14,10 @@ format of the vault.
### Primitives ### Primitives
Two cryptographic primitives were selected for use in Aegis. An Authenticated Two cryptographic primitives were selected for use in Aegis. An Authenticated
Encryption with Associated Data (AEAD) cipher and a Key Derivation Function Encryption with Associated Data
(KDF). ([AEAD](https://en.wikipedia.org/wiki/Authenticated_encryption#Authenticated_encryption_with_associated_data))
cipher and a Key Derivation Function
([KDF](https://en.wikipedia.org/wiki/Key_derivation_function)).
#### AEAD #### AEAD
@ -36,15 +38,16 @@ This is a reasonable assumption to make, because it's highly unlikely that an
Aegis user will ever come close to saving the vault 2<sup>32</sup> times. Aegis user will ever come close to saving the vault 2<sup>32</sup> times.
_Switching to a nonce misuse-resistant cipher like AES-GCM-SIV or a cipher with _Switching to a nonce misuse-resistant cipher like AES-GCM-SIV or a cipher with
a larger (192 bits) nonce like XChaCha-Poly1305 will be considered in the future._ a larger (192 bits) nonce like XChaCha-Poly1305 will be considered in the
future._
#### KDF #### KDF
__scrypt__ is used as the KDF to derive a key from a user-provided password, [__scrypt__](https://en.wikipedia.org/wiki/Scrypt) is used as the KDF to derive
with the following parameters: a key from a user-provided password, with the following parameters:
| Parameter | Value | | Parameter | Value |
| :-------- | :------------- | |:----------|:---------------|
| N | 2<sup>15</sup> | | N | 2<sup>15</sup> |
| r | 8 | | r | 8 |
| p | 1 | | p | 1 |
@ -104,12 +107,17 @@ shown below:
} }
``` ```
It starts with a ``version`` number and a ``header``. If a backwards It starts with a ``version`` number. If a forwards incompatible change is
incompatible change is introduced to the content format, the version number will introduced to the vault format, the version number will be incremented. The
be incremented. The vault contents are stored under ``db``. Its value depends on current version of the vault format is ``1``.
whether the vault is encrypted or not. If it is, the value is a string containing
the Base64 encoded (with padding) ciphertext of the vault contents. Otherwise, The [``header``](#header), if not empty, contains the list of slots and the
the value is a JSON object. encryption parameters used for decrypting the vault.
The vault contents are stored under ``db``. Its value depends on whether the
vault is encrypted or not. If it is, the value is a string containing the Base64
encoded (with padding) ciphertext of the vault contents. Otherwise, the value is
a JSON object. See [vault content](#vault-content) for details.
Full examples of a [plain text Full examples of a [plain text
vault](/app/src/test/resources/com/beemdevelopment/aegis/importers/aegis_plain.json) vault](/app/src/test/resources/com/beemdevelopment/aegis/importers/aegis_plain.json)
@ -122,9 +130,14 @@ password: [decrypt.py](/docs/decrypt.py).
### Header ### Header
The header starts with the list of ``slots``. It also has a ``params`` object The header starts with the list of [``slots``](#slots-1). Each slot contains the
that holds the ``nonce`` and ``tag`` that were produced during encryption, master key in an encrypted form together with the key wrapping parameters.
encoded as a hexadecimal string.
It also has a ``params`` object that holds the ``nonce`` and ``tag`` that were
produced during the AES-GCM encryption, encoded as a hexadecimal string. These
encryption parameters together with the master key (which can be retrieved by
decrypting the ``key`` from one of the slots) are used to decrypt the vault
contents found in the ``db`` field.
Setting ``slots`` and ``params`` to null indicates that the vault is not Setting ``slots`` and ``params`` to null indicates that the vault is not
encrypted and Aegis will try to parse it as such. encrypted and Aegis will try to parse it as such.
@ -141,13 +154,13 @@ encrypted and Aegis will try to parse it as such.
#### Slots #### Slots
The different slot types are identified with a numerical ID. The different slot types are identified with a numerical ID.
| Type | ID | | Type | ID |
| :---------- | :--- | |:----------|:-----|
| Raw | 0x00 | | Raw | 0x00 |
| Password | 0x01 | | Password | 0x01 |
| Biometric | 0x02 | | Biometric | 0x02 |
##### Raw ##### Raw
@ -182,7 +195,7 @@ Raw slots don't imply use of a particular storage type.
As noted earlier, scrypt is used to derive a 256-bit key from a user-provided As noted earlier, scrypt is used to derive a 256-bit key from a user-provided
password. A random 256-bit ``salt`` is generated and passed to scrypt to protect password. A random 256-bit ``salt`` is generated and passed to scrypt to protect
against rainbow table attacks. Its stored along with the ``N``, ``r`` and ``p`` against rainbow table attacks. It's stored along with the ``N``, ``r`` and ``p``
parameters. parameters.
```json ```json
@ -201,56 +214,69 @@ parameters.
} }
``` ```
### Content ### Vault content
The content is a JSON object encoded in UTF-8. The content is a JSON object encoded in UTF-8.
```json ```json
{ {
"version": 1, "version": 3,
"entries": [] "entries": [],
"groups": []
} }
``` ```
It has a ``version`` number and a list of ``entries``. If a backwards It has a ``version`` number, a list of ``entries`` and a list of ``groups``. If
incompatible change is introduced to the content format, the version number will a forwards incompatible change is introduced to the content format, the version
be incremented. number will be incremented. The current version of the vault content format is
``3``.
| Field | Type | Description |
|:------------|:------|:-----------------------------------------|
| ``version`` | int | The version of the vault content format. |
| ``entries`` | array | A list of [entries](#entries). |
| ``groups`` | array | A list of [groups](#groups). |
#### Entries #### Entries
Each entry has a unique randomly generated ``UUID`` (version 4), as well as a Each entry has a unique randomly generated ``UUID``, as well as a ``name`` and
``name`` and ``issuer`` to identify the account name and service that the token ``issuer`` to identify the account name and service that the token is for.
is for. Entries can also have an icon. These are JPEG's encoded in Base64 with
padding. The ``info`` object holds information specific to the OTP type. The Entries hold the following fields:
``secret`` is encoded in Base32 without padding.
| Field | Type | Description |
|:--------------|:---------------|:--------------------------------------------------------------------------------|
| ``type`` | string | The type of the OTP algorithm. See table below. |
| ``uuid`` | string | A UUID (version 4). |
| ``name`` | string | The account name. |
| ``issuer`` | string | The service that the token is for. |
| ``note`` | string | A personal note about the entry. |
| ``icon`` | string \| null | JPEG's encoded in Base64 with padding. |
| ``icon_mime`` | string \| null | The MIME type of the icon. Is null if ``icon`` is null. |
| ``icon_hash`` | string \| null | The SHA-256 hash of the icon. Is null if ``icon`` is null. |
| ``favorite`` | bool | Whether the entry is a favorite or not. |
| ``info`` | object | Information specific to the OTP type. |
| ``groups`` | array | A list of UUIDs of groups that the entry is a member of. See [Groups](#groups). |
The ``info`` object contains different fields depending on the type of the OTP.
There are a number of supported types: There are a number of supported types:
| Type | ID | Spec | | Type | ID | Spec |
| :------------------ | :------- | :-------- | |:-------|:---------|:----------------------------------------------------------|
| HOTP | "hotp" | [RFC 4226](https://datatracker.ietf.org/doc/html/rfc4226) | HOTP | "hotp" | [RFC 4226](https://datatracker.ietf.org/doc/html/rfc4226) |
| TOTP | "totp" | [RFC 6238](https://datatracker.ietf.org/doc/html/rfc6238) | TOTP | "totp" | [RFC 6238](https://datatracker.ietf.org/doc/html/rfc6238) |
| Steam | "steam" | N/A | Steam | "steam" | N/A |
| Yandex | "yandex" | N/A | MOTP | "motp" | N/A |
| Yandex | "yandex" | N/A |
There is no specification available for Steam's OTP algorithm. It's essentially Common ``info`` fields for all types:
the same as TOTP, but it uses a different final encoding step. Aegis'
implementation of it can be found in
[crypto/otp/OTP.java](https://github.com/beemdevelopment/Aegis/blob/master/app/src/main/java/com/beemdevelopment/aegis/crypto/otp/OTP.java).
There is also no specification available for Yandex's OTP algorithm. Aegis' | Field | Type | Description |
implementation can be found in |:-----------|:-------|:-----------------------------------|
[crypto/otp/YAOTP.java](https://github.com/beemdevelopment/Aegis/blob/master/app/src/main/java/com/beemdevelopment/aegis/crypto/otp/YAOTP.java) | ``secret`` | string | The Base32 encoded secret. |
| ``algo`` | string | The hashing algorithm. |
The following algorithms are supported for HOTP and TOTP: | ``digits`` | int | The number of digits in the token. |
| Algorithm | ID |
| :-------- | :------- |
| SHA-1 | "SHA1" |
| SHA-256 | "SHA256" |
| SHA-512 | "SHA512" |
For Steam, only SHA-1 is supported. For Yandex, only SHA-256 is supported.
Example of a TOTP entry: Example of a TOTP entry:
@ -260,12 +286,105 @@ Example of a TOTP entry:
"uuid": "01234567-89ab-cdef-0123-456789abcdef", "uuid": "01234567-89ab-cdef-0123-456789abcdef",
"name": "Bob", "name": "Bob",
"issuer": "Google", "issuer": "Google",
"note": "Main account",
"favorite": false,
"icon": null, "icon": null,
"icon_mime": null,
"icon_hash": null,
"info": { "info": {
"secret": "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567", "secret": "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567",
"algo": "SHA1", "algo": "SHA1",
"digits": 6, "digits": 6,
"period": 30 "period": 30
} },
"groups": [
"01234567-89ab-cdef-0123-456789abcdef"
]
}
```
##### HOTP and TOTP
TOTP uses the ``period`` field, which is the time step in seconds. HOTP uses the
``counter`` field, which is incremented every time a token is generated.
The following algorithms are supported for HOTP and TOTP:
| Algorithm | ID |
|:----------|:---------|
| SHA-1 | "SHA1" |
| SHA-256 | "SHA256" |
| SHA-512 | "SHA512" |
##### Steam
There is no specification available for Steam's OTP algorithm. It's essentially
the same as TOTP, but it uses a different final encoding step. Aegis'
implementation of it can be found in
[crypto/otp/OTP.java](/app/src/main/java/com/beemdevelopment/aegis/crypto/otp/OTP.java).
A couple of fields have fixed values:
| Field | Value |
|:-----------|:-------|
| ``algo`` | "SHA1" |
| ``period`` | 30 |
| ``digits`` | 5 |
##### MOTP
There is no specification available for MOTP. Aegis' implementation of it can be
found in
[crypto/otp/MOTP.java](/app/src/main/java/com/beemdevelopment/aegis/crypto/otp/MOTP.java).
A couple of fields have fixed values:
| Field | Value |
|:-----------|:------|
| ``algo`` | "MD5" |
| ``period`` | 10 |
| ``digits`` | 6 |
MOTP-specific fields:
| Field | Type | Description |
|:--------|:-------|:------------|
| ``pin`` | string | 4-digit PIN |
##### Yandex
There is no specification available for Yandex's OTP algorithm. Aegis'
implementation can be found in
[crypto/otp/YAOTP.java](/app/src/main/java/com/beemdevelopment/aegis/crypto/otp/YAOTP.java)
A couple of fields have fixed values:
| Field | Value |
|:-----------|:---------|
| ``algo`` | "SHA256" |
| ``period`` | 30 |
| ``digits`` | 8 |
Yandex-specific fields:
| Field | Type | Description |
|:--------|:-------|:---------------|
| ``pin`` | string | 4-16 digit PIN |
#### Groups
A group consists of a ``name`` and a randomly generated ``uuid`` (version 4).
| Field | Type | Description |
|:---------|:-------|:-----------------------|
| ``uuid`` | string | A UUID (version 4). |
| ``name`` | string | The name of the group. |
Example:
```json
{
"uuid": "01234567-89ab-cdef-0123-456789abcdef",
"name": "Personal"
} }
``` ```