mirror of
https://github.com/bitwarden/mobile
synced 2025-12-21 10:43:22 +00:00
[PM-5731] Create C# WebAuthn authenticator to support maui apps (#2951)
* [PM-5731] feat: implement get assertion params object * [PM-5731] feat: add first test * [PM-5731] feat: add rp mismatch test * [PM-5731] feat: ask for credentials when found * [PM-5731] feat: find discoverable credentials * [PM-5731] feat: add tests for successful UV requests * [PM-5731] feat: add user does not consent test * [PM-5731] feat: check for UV when reprompt is active * [PM-5731] fix: tests a bit, needed some additional "arrange" steps * [PM-5731] feat: add support for counter * [PM-5731] feat: implement assertion without signature * [PM-5732] feat: finish authenticator assertion implementation note: CryptoFunctionService still needs Sign implemenation * [PM-5731] chore: minor clean up * [PM-5731] feat: scaffold make credential * [PM-5731] feat: start implementing attestation * [PM-5731] feat: implement credential exclusion * [PM-5731] feat: add new credential confirmaiton * [PM-5731] feat: implement credential creation * [PM-5731] feat: add user verification checks * [PM-5731] feat: add unknown error handling * [PM-5731] chore: clean up unusued params * [PM-5731] feat: partial attestation implementation * [PM-5731] feat: implement key generation * [PM-5731] feat: return public key in DER format * [PM-5731] feat: implement signing * [PM-5731] feat: remove logging * [PM-5731] chore: use primary constructor * [PM-5731] chore: add Async to method names * [PM-5731] feat: add support for silent discoverability * [PM-5731] feat: add support for specifying user presence requirement * [PM-5731] feat: ensure unlocked vault * [PM-5731] chore: clean up and refactor assertion tests * [PM-5731] chore: clean up and refactor attestation tests * [PM-5731] chore: add user presence todo comment * [PM-5731] feat: scaffold fido2 client * PM-5731 Fix build updating discoverable flag * [PM-5731] fix: failing test * [PM-5731] feat: add sameOriginWithAncestor and user id length checks * [PM-5731] feat: add incomplete rpId verification * [PM-5731] chore: document uri helpers * [PM-5731] feat: implement fido2 client createCredential * [PM-5731] feat: implement credential assertion in client * fix wrong signature format (cherry picked from commita1c9ebf01f) * [PM-5731] fix: issues after cherry-pick * Fix incompatible GUID conversions (cherry picked from commitc801b2fc3a) * [PM-5731] chore: remove default constructor * [PM-5731] feat: refactor user interface to increase flexibility * [PM-5731] feat: implement generic assertion user interface class * [PM-5731] feat: remove ability to make user presence optional * [PM-5731] chore: remove logging comments * [PM-5731] feat: add native reprompt support to the authenticator * [PM-5731] feat: allow pre and post UV * [PM-5731] chore: add `Async` to method name. Remove `I` from struct * [PM-5731] fix: discoverable string repr lowercase * [PM-5731] chore: don't use C# 12 features * [PM-5731] fix: replace magic strings and numbers with contants and enums * [PM-5731] fix: use UTC creation date * [PM-5731] fix: formatting * [PM-5731] chore: use properties for public fields * [PM-5731] chore: remove TODO * [PM-5731] fix: IsValidRpId --------- Co-authored-by: Federico Maccaroni <fedemkr@gmail.com> Co-authored-by: mpbw2 <59324545+mpbw2@users.noreply.github.com>
This commit is contained in:
Andreas Coroiu
GitHub
456
src/Core/Services/Fido2AuthenticatorService.cs
Normal file
456
src/Core/Services/Fido2AuthenticatorService.cs
Normal file
@@ -0,0 +1,456 @@
|
||||
using Bit.Core.Abstractions;
|
||||
using Bit.Core.Models.View;
|
||||
using Bit.Core.Enums;
|
||||
using Bit.Core.Utilities.Fido2;
|
||||
using Bit.Core.Utilities;
|
||||
using System.Formats.Cbor;
|
||||
using System.Security.Cryptography;
|
||||
|
||||
namespace Bit.Core.Services
|
||||
{
|
||||
public class Fido2AuthenticatorService : IFido2AuthenticatorService
|
||||
{
|
||||
// AAGUID: d548826e-79b4-db40-a3d8-11116f7e8349
|
||||
public static readonly byte[] AAGUID = new byte[] { 0xd5, 0x48, 0x82, 0x6e, 0x79, 0xb4, 0xdb, 0x40, 0xa3, 0xd8, 0x11, 0x11, 0x6f, 0x7e, 0x83, 0x49 };
|
||||
|
||||
private readonly ICipherService _cipherService;
|
||||
private readonly ISyncService _syncService;
|
||||
private readonly ICryptoFunctionService _cryptoFunctionService;
|
||||
|
||||
public Fido2AuthenticatorService(ICipherService cipherService, ISyncService syncService, ICryptoFunctionService cryptoFunctionService)
|
||||
{
|
||||
_cipherService = cipherService;
|
||||
_syncService = syncService;
|
||||
_cryptoFunctionService = cryptoFunctionService;
|
||||
}
|
||||
|
||||
public async Task<Fido2AuthenticatorMakeCredentialResult> MakeCredentialAsync(Fido2AuthenticatorMakeCredentialParams makeCredentialParams, IFido2MakeCredentialUserInterface userInterface)
|
||||
{
|
||||
if (makeCredentialParams.CredTypesAndPubKeyAlgs.All((p) => p.Alg != (int) Fido2AlgorithmIdentifier.ES256))
|
||||
{
|
||||
throw new NotSupportedError();
|
||||
}
|
||||
|
||||
await userInterface.EnsureUnlockedVaultAsync();
|
||||
await _syncService.FullSyncAsync(false);
|
||||
|
||||
var existingCipherIds = await FindExcludedCredentialsAsync(
|
||||
makeCredentialParams.ExcludeCredentialDescriptorList
|
||||
);
|
||||
if (existingCipherIds.Length > 0) {
|
||||
await userInterface.InformExcludedCredentialAsync(existingCipherIds);
|
||||
throw new NotAllowedError();
|
||||
}
|
||||
|
||||
var response = await userInterface.ConfirmNewCredentialAsync(new Fido2ConfirmNewCredentialParams {
|
||||
CredentialName = makeCredentialParams.RpEntity.Name,
|
||||
UserName = makeCredentialParams.UserEntity.Name,
|
||||
UserVerification = makeCredentialParams.RequireUserVerification
|
||||
});
|
||||
|
||||
var cipherId = response.CipherId;
|
||||
var userVerified = response.UserVerified;
|
||||
string credentialId;
|
||||
if (cipherId == null) {
|
||||
throw new NotAllowedError();
|
||||
}
|
||||
|
||||
try {
|
||||
var keyPair = GenerateKeyPair();
|
||||
var fido2Credential = CreateCredentialView(makeCredentialParams, keyPair.privateKey);
|
||||
|
||||
var encrypted = await _cipherService.GetAsync(cipherId);
|
||||
var cipher = await encrypted.DecryptAsync();
|
||||
|
||||
if (!userVerified && (makeCredentialParams.RequireUserVerification || cipher.Reprompt != CipherRepromptType.None)) {
|
||||
throw new NotAllowedError();
|
||||
}
|
||||
|
||||
cipher.Login.Fido2Credentials = [fido2Credential];
|
||||
var reencrypted = await _cipherService.EncryptAsync(cipher);
|
||||
await _cipherService.SaveWithServerAsync(reencrypted);
|
||||
credentialId = fido2Credential.CredentialId;
|
||||
|
||||
var authData = await GenerateAuthDataAsync(
|
||||
rpId: makeCredentialParams.RpEntity.Id,
|
||||
counter: fido2Credential.CounterValue,
|
||||
userPresence: true,
|
||||
userVerification: userVerified,
|
||||
credentialId: credentialId.GuidToRawFormat(),
|
||||
publicKey: keyPair.publicKey
|
||||
);
|
||||
|
||||
return new Fido2AuthenticatorMakeCredentialResult
|
||||
{
|
||||
CredentialId = credentialId.GuidToRawFormat(),
|
||||
AttestationObject = EncodeAttestationObject(authData),
|
||||
AuthData = authData,
|
||||
PublicKey = keyPair.publicKey.ExportDer(),
|
||||
PublicKeyAlgorithm = (int) Fido2AlgorithmIdentifier.ES256,
|
||||
};
|
||||
} catch (NotAllowedError) {
|
||||
throw;
|
||||
} catch (Exception) {
|
||||
throw new UnknownError();
|
||||
}
|
||||
}
|
||||
|
||||
public async Task<Fido2AuthenticatorGetAssertionResult> GetAssertionAsync(Fido2AuthenticatorGetAssertionParams assertionParams, IFido2GetAssertionUserInterface userInterface)
|
||||
{
|
||||
List<CipherView> cipherOptions;
|
||||
|
||||
await userInterface.EnsureUnlockedVaultAsync();
|
||||
await _syncService.FullSyncAsync(false);
|
||||
|
||||
if (assertionParams.AllowCredentialDescriptorList?.Length > 0) {
|
||||
cipherOptions = await FindCredentialsByIdAsync(
|
||||
assertionParams.AllowCredentialDescriptorList,
|
||||
assertionParams.RpId
|
||||
);
|
||||
} else {
|
||||
cipherOptions = await FindCredentialsByRpAsync(assertionParams.RpId);
|
||||
}
|
||||
|
||||
if (cipherOptions.Count == 0) {
|
||||
throw new NotAllowedError();
|
||||
}
|
||||
|
||||
var response = await userInterface.PickCredentialAsync(
|
||||
cipherOptions.Select((cipher) => new Fido2GetAssertionUserInterfaceCredential {
|
||||
CipherId = cipher.Id,
|
||||
RequireUserVerification = assertionParams.RequireUserVerification || cipher.Reprompt != CipherRepromptType.None
|
||||
}).ToArray()
|
||||
);
|
||||
var selectedCipherId = response.CipherId;
|
||||
var userVerified = response.UserVerified;
|
||||
|
||||
var selectedCipher = cipherOptions.FirstOrDefault((c) => c.Id == selectedCipherId);
|
||||
if (selectedCipher == null) {
|
||||
throw new NotAllowedError();
|
||||
}
|
||||
|
||||
if (!userVerified && (assertionParams.RequireUserVerification || selectedCipher.Reprompt != CipherRepromptType.None)) {
|
||||
throw new NotAllowedError();
|
||||
}
|
||||
|
||||
try {
|
||||
var selectedFido2Credential = selectedCipher.Login.MainFido2Credential;
|
||||
var selectedCredentialId = selectedFido2Credential.CredentialId;
|
||||
|
||||
if (selectedFido2Credential.CounterValue != 0) {
|
||||
++selectedFido2Credential.CounterValue;
|
||||
}
|
||||
|
||||
await _cipherService.UpdateLastUsedDateAsync(selectedCipher.Id);
|
||||
var encrypted = await _cipherService.EncryptAsync(selectedCipher);
|
||||
await _cipherService.SaveWithServerAsync(encrypted);
|
||||
|
||||
var authenticatorData = await GenerateAuthDataAsync(
|
||||
rpId: selectedFido2Credential.RpId,
|
||||
userPresence: true,
|
||||
userVerification: userVerified,
|
||||
counter: selectedFido2Credential.CounterValue
|
||||
);
|
||||
|
||||
var signature = GenerateSignature(
|
||||
authData: authenticatorData,
|
||||
clientDataHash: assertionParams.Hash,
|
||||
privateKey: selectedFido2Credential.KeyBytes
|
||||
);
|
||||
|
||||
return new Fido2AuthenticatorGetAssertionResult
|
||||
{
|
||||
SelectedCredential = new Fido2AuthenticatorGetAssertionSelectedCredential
|
||||
{
|
||||
Id = selectedCredentialId.GuidToRawFormat(),
|
||||
UserHandle = selectedFido2Credential.UserHandleValue
|
||||
},
|
||||
AuthenticatorData = authenticatorData,
|
||||
Signature = signature
|
||||
};
|
||||
} catch (Exception) {
|
||||
throw new UnknownError();
|
||||
}
|
||||
}
|
||||
|
||||
public async Task<Fido2AuthenticatorDiscoverableCredentialMetadata[]> SilentCredentialDiscoveryAsync(string rpId)
|
||||
{
|
||||
var credentials = (await FindCredentialsByRpAsync(rpId)).Select(cipher => new Fido2AuthenticatorDiscoverableCredentialMetadata {
|
||||
Type = Constants.DefaultFido2CredentialType,
|
||||
Id = cipher.Login.MainFido2Credential.CredentialId.GuidToRawFormat(),
|
||||
RpId = cipher.Login.MainFido2Credential.RpId,
|
||||
UserHandle = cipher.Login.MainFido2Credential.UserHandleValue,
|
||||
UserName = cipher.Login.MainFido2Credential.UserName
|
||||
}).ToArray();
|
||||
|
||||
return credentials;
|
||||
}
|
||||
|
||||
/// <summary>
|
||||
/// Finds existing crendetials and returns the `CipherId` for each one
|
||||
/// </summary>
|
||||
private async Task<string[]> FindExcludedCredentialsAsync(
|
||||
PublicKeyCredentialDescriptor[] credentials
|
||||
) {
|
||||
if (credentials == null || credentials.Length == 0) {
|
||||
return Array.Empty<string>();
|
||||
}
|
||||
|
||||
var ids = new List<string>();
|
||||
|
||||
foreach (var credential in credentials)
|
||||
{
|
||||
try
|
||||
{
|
||||
ids.Add(credential.Id.GuidToStandardFormat());
|
||||
} catch {}
|
||||
}
|
||||
|
||||
if (ids.Count == 0) {
|
||||
return Array.Empty<string>();
|
||||
}
|
||||
|
||||
var ciphers = await _cipherService.GetAllDecryptedAsync();
|
||||
return ciphers
|
||||
.FindAll(
|
||||
(cipher) =>
|
||||
!cipher.IsDeleted &&
|
||||
cipher.OrganizationId == null &&
|
||||
cipher.Type == CipherType.Login &&
|
||||
cipher.Login.HasFido2Credentials &&
|
||||
ids.Contains(cipher.Login.MainFido2Credential.CredentialId)
|
||||
)
|
||||
.Select((cipher) => cipher.Id)
|
||||
.ToArray();
|
||||
}
|
||||
|
||||
private async Task<List<CipherView>> FindCredentialsByIdAsync(PublicKeyCredentialDescriptor[] credentials, string rpId)
|
||||
{
|
||||
var ids = new List<string>();
|
||||
|
||||
foreach (var credential in credentials)
|
||||
{
|
||||
try
|
||||
{
|
||||
ids.Add(credential.Id.GuidToStandardFormat());
|
||||
}
|
||||
catch {}
|
||||
}
|
||||
|
||||
if (ids.Count == 0)
|
||||
{
|
||||
return new List<CipherView>();
|
||||
}
|
||||
|
||||
var ciphers = await _cipherService.GetAllDecryptedAsync();
|
||||
return ciphers.FindAll((cipher) =>
|
||||
!cipher.IsDeleted &&
|
||||
cipher.Type == CipherType.Login &&
|
||||
cipher.Login.HasFido2Credentials &&
|
||||
cipher.Login.MainFido2Credential.RpId == rpId &&
|
||||
ids.Contains(cipher.Login.MainFido2Credential.CredentialId)
|
||||
);
|
||||
}
|
||||
|
||||
private async Task<List<CipherView>> FindCredentialsByRpAsync(string rpId)
|
||||
{
|
||||
var ciphers = await _cipherService.GetAllDecryptedAsync();
|
||||
return ciphers.FindAll((cipher) =>
|
||||
!cipher.IsDeleted &&
|
||||
cipher.Type == CipherType.Login &&
|
||||
cipher.Login.HasFido2Credentials &&
|
||||
cipher.Login.MainFido2Credential.RpId == rpId &&
|
||||
cipher.Login.MainFido2Credential.DiscoverableValue
|
||||
);
|
||||
}
|
||||
|
||||
// TODO: Move this to a separate service
|
||||
private (PublicKey publicKey, byte[] privateKey) GenerateKeyPair()
|
||||
{
|
||||
var dsa = ECDsa.Create();
|
||||
dsa.GenerateKey(ECCurve.NamedCurves.nistP256);
|
||||
var privateKey = dsa.ExportPkcs8PrivateKey();
|
||||
|
||||
return (new PublicKey(dsa), privateKey);
|
||||
}
|
||||
|
||||
private Fido2CredentialView CreateCredentialView(Fido2AuthenticatorMakeCredentialParams makeCredentialsParams, byte[] privateKey)
|
||||
{
|
||||
return new Fido2CredentialView {
|
||||
CredentialId = Guid.NewGuid().ToString(),
|
||||
KeyType = Constants.DefaultFido2CredentialType,
|
||||
KeyAlgorithm = Constants.DefaultFido2CredentialAlgorithm,
|
||||
KeyCurve = Constants.DefaultFido2CredentialCurve,
|
||||
KeyValue = CoreHelpers.Base64UrlEncode(privateKey),
|
||||
RpId = makeCredentialsParams.RpEntity.Id,
|
||||
UserHandle = CoreHelpers.Base64UrlEncode(makeCredentialsParams.UserEntity.Id),
|
||||
UserName = makeCredentialsParams.UserEntity.Name,
|
||||
CounterValue = 0,
|
||||
RpName = makeCredentialsParams.RpEntity.Name,
|
||||
// UserDisplayName = makeCredentialsParams.UserEntity.DisplayName,
|
||||
DiscoverableValue = makeCredentialsParams.RequireResidentKey,
|
||||
CreationDate = DateTime.UtcNow
|
||||
};
|
||||
}
|
||||
|
||||
private async Task<byte[]> GenerateAuthDataAsync(
|
||||
string rpId,
|
||||
bool userVerification,
|
||||
bool userPresence,
|
||||
int counter,
|
||||
byte[] credentialId = null,
|
||||
PublicKey publicKey = null
|
||||
) {
|
||||
var isAttestation = credentialId != null && publicKey != null;
|
||||
|
||||
List<byte> authData = new List<byte>();
|
||||
|
||||
var rpIdHash = await _cryptoFunctionService.HashAsync(rpId, CryptoHashAlgorithm.Sha256);
|
||||
authData.AddRange(rpIdHash);
|
||||
|
||||
var flags = AuthDataFlags(
|
||||
extensionData: false,
|
||||
attestationData: isAttestation,
|
||||
userVerification: userVerification,
|
||||
userPresence: userPresence
|
||||
);
|
||||
authData.Add(flags);
|
||||
|
||||
authData.AddRange([
|
||||
(byte)(counter >> 24),
|
||||
(byte)(counter >> 16),
|
||||
(byte)(counter >> 8),
|
||||
(byte)counter
|
||||
]);
|
||||
|
||||
if (isAttestation)
|
||||
{
|
||||
var attestedCredentialData = new List<byte>();
|
||||
|
||||
attestedCredentialData.AddRange(AAGUID);
|
||||
|
||||
// credentialIdLength (2 bytes) and credential Id
|
||||
var credentialIdLength = new byte[] {
|
||||
(byte)((credentialId.Length - (credentialId.Length & 0xff)) / 256),
|
||||
(byte)(credentialId.Length & 0xff)
|
||||
};
|
||||
attestedCredentialData.AddRange(credentialIdLength);
|
||||
attestedCredentialData.AddRange(credentialId);
|
||||
attestedCredentialData.AddRange(publicKey.ExportCose());
|
||||
|
||||
authData.AddRange(attestedCredentialData);
|
||||
}
|
||||
|
||||
return authData.ToArray();
|
||||
}
|
||||
|
||||
private byte AuthDataFlags(bool extensionData, bool attestationData, bool userVerification, bool userPresence, bool backupEligibility = true, bool backupState = true) {
|
||||
byte flags = 0;
|
||||
|
||||
if (extensionData) {
|
||||
flags |= 0b1000000;
|
||||
}
|
||||
|
||||
if (attestationData) {
|
||||
flags |= 0b01000000;
|
||||
}
|
||||
|
||||
if (backupState)
|
||||
{
|
||||
flags |= 0b00010000;
|
||||
}
|
||||
|
||||
if (backupEligibility)
|
||||
{
|
||||
flags |= 0b00001000;
|
||||
}
|
||||
|
||||
if (userVerification) {
|
||||
flags |= 0b00000100;
|
||||
}
|
||||
|
||||
if (userPresence) {
|
||||
flags |= 0b00000001;
|
||||
}
|
||||
|
||||
return flags;
|
||||
}
|
||||
|
||||
private byte[] EncodeAttestationObject(byte[] authData) {
|
||||
var attestationObject = new CborWriter(CborConformanceMode.Ctap2Canonical);
|
||||
attestationObject.WriteStartMap(3);
|
||||
attestationObject.WriteTextString("fmt");
|
||||
attestationObject.WriteTextString("none");
|
||||
attestationObject.WriteTextString("attStmt");
|
||||
attestationObject.WriteStartMap(0);
|
||||
attestationObject.WriteEndMap();
|
||||
attestationObject.WriteTextString("authData");
|
||||
attestationObject.WriteByteString(authData);
|
||||
attestationObject.WriteEndMap();
|
||||
|
||||
return attestationObject.Encode();
|
||||
}
|
||||
|
||||
// TODO: Move this to a separate service
|
||||
private byte[] GenerateSignature(byte[] authData, byte[] clientDataHash, byte[] privateKey)
|
||||
{
|
||||
var sigBase = authData.Concat(clientDataHash).ToArray();
|
||||
var dsa = ECDsa.Create();
|
||||
dsa.ImportPkcs8PrivateKey(privateKey, out var bytesRead);
|
||||
|
||||
if (bytesRead == 0)
|
||||
{
|
||||
throw new Exception("Failed to import private key");
|
||||
}
|
||||
|
||||
return dsa.SignData(sigBase, HashAlgorithmName.SHA256, DSASignatureFormat.Rfc3279DerSequence);
|
||||
}
|
||||
|
||||
private class PublicKey
|
||||
{
|
||||
private readonly ECDsa _dsa;
|
||||
|
||||
public PublicKey(ECDsa dsa) {
|
||||
_dsa = dsa;
|
||||
}
|
||||
|
||||
public byte[] X => _dsa.ExportParameters(false).Q.X;
|
||||
public byte[] Y => _dsa.ExportParameters(false).Q.Y;
|
||||
|
||||
public byte[] ExportDer()
|
||||
{
|
||||
return _dsa.ExportSubjectPublicKeyInfo();
|
||||
}
|
||||
|
||||
public byte[] ExportCose()
|
||||
{
|
||||
var result = new CborWriter(CborConformanceMode.Ctap2Canonical);
|
||||
result.WriteStartMap(5);
|
||||
|
||||
// kty = EC2
|
||||
result.WriteInt32(1);
|
||||
result.WriteInt32(2);
|
||||
|
||||
// alg = ES256
|
||||
result.WriteInt32(3);
|
||||
result.WriteInt32((int) Fido2AlgorithmIdentifier.ES256);
|
||||
|
||||
// crv = P-256
|
||||
result.WriteInt32(-1);
|
||||
result.WriteInt32(1);
|
||||
|
||||
// x
|
||||
result.WriteInt32(-2);
|
||||
result.WriteByteString(X);
|
||||
|
||||
// y
|
||||
result.WriteInt32(-3);
|
||||
result.WriteByteString(Y);
|
||||
|
||||
result.WriteEndMap();
|
||||
|
||||
return result.Encode();
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user