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Added Android-safetynet attestation format.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,96 @@ | ||
| using System.Formats.Cbor; | ||
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| namespace KristofferStrube.Blazor.WebAuthentication; | ||
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| /// <summary> | ||
| /// When the authenticator is a platform authenticator on certain Android platforms, the attestation statement may be based on the SafetyNet API. | ||
| /// In this case the authenticator data is completely controlled by the caller of the SafetyNet API (typically an application running on the Android platform) | ||
| /// and the attestation statement provides some statements about the health of the platform and the identity of the calling application | ||
| /// </summary> | ||
| /// <remarks><see href="https://www.w3.org/TR/webauthn-3/#sctn-android-safetynet-attestation">See the API definition here</see>.</remarks> | ||
| public class AndroidSafetyNetAttestationStatement : AttestationStatement | ||
| { | ||
| /// <summary> | ||
| /// The algorithm used to generate the attestation signature. | ||
| /// </summary> | ||
| public required string Version { get; set; } | ||
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| /// <summary> | ||
| /// The UTF-8 encoded result of the <c>getJwsResult()</c> call of the SafetyNet API. | ||
| /// This value is a JWS object in Compact Serialization. | ||
| /// </summary> | ||
| public required byte[] Response { get; set; } | ||
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| internal static AndroidSafetyNetAttestationStatement ReadAttestationStatement(CborReader cborReader) | ||
| { | ||
| CborReaderState state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.TextString) | ||
| { | ||
| throw new FormatException($"Attestation Statement's second key was of type '{state}' but '{CborReaderState.TextString}' was expected."); | ||
| } | ||
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| string label = cborReader.ReadTextString(); | ||
| if (label is not "attStmt") | ||
| { | ||
| throw new FormatException($"Attestation Statement's second key was '{label}' but 'attStmt' was expected."); | ||
| } | ||
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.StartMap) | ||
| { | ||
| throw new FormatException($"Attestation Statement's 'attStmt' was of type '{state}' but '{CborReaderState.StartMap}' was expected."); | ||
| } | ||
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| int? mapSize = cborReader.ReadStartMap(); | ||
| if (mapSize is not 2) | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format had '{mapSize}' entries but '2' was expected."); | ||
| } | ||
|
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.TextString) | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format's first key was of type '{state}' but '{CborReaderState.TextString}' was expected."); | ||
| } | ||
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| label = cborReader.ReadTextString(); | ||
| if (label is not "ver") | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format's first key was '{label}' but 'ver' was expected."); | ||
| } | ||
|
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.NegativeInteger) | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format's 'ver' was of type '{state}' but '{CborReaderState.TextString}' was expected."); | ||
| } | ||
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| string version = cborReader.ReadTextString(); | ||
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.TextString) | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format's second key was of type '{state}' but '{CborReaderState.TextString}' was expected."); | ||
| } | ||
|
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| label = cborReader.ReadTextString(); | ||
| if (label is not "response") | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format's second key was '{label}' but 'response' was expected."); | ||
| } | ||
|
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.ByteString) | ||
| { | ||
| throw new FormatException($"Attestation Statement's packed format's 'response' was of type '{state}' but '{CborReaderState.ByteString}' was expected."); | ||
| } | ||
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| byte[] response = cborReader.ReadByteString(); | ||
|
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| return new() | ||
| { | ||
| Version = version, | ||
| Response = response | ||
| }; | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,56 @@ | ||
| using System.Formats.Cbor; | ||
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| namespace KristofferStrube.Blazor.WebAuthentication; | ||
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| /// <summary> | ||
| /// WebAuthn supports pluggable attestation statement formats. | ||
| /// Attestation statement formats are identified by a string, called an attestation statement format identifier, chosen by the author of the attestation statement format. | ||
| /// </summary> | ||
| /// <remarks><see href="https://www.w3.org/TR/webauthn-3/#sctn-defined-attestation-formats">See the API definition here</see>.</remarks> | ||
| public abstract class AttestationStatement | ||
| { | ||
| public static AttestationStatement ReadFromBase64EncodedAttestationStatement(string input) | ||
| { | ||
| CborReader cborReader = new(Convert.FromBase64String(input)); | ||
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| CborReaderState state = cborReader.PeekState(); | ||
|
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| if (state is not CborReaderState.StartMap) | ||
| { | ||
| throw new FormatException("Attestation Statement did not start with a map."); | ||
| } | ||
|
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| int? mapSize = cborReader.ReadStartMap(); | ||
| if (mapSize is not 3) | ||
| { | ||
| throw new FormatException($"Attestation Statement had '{mapSize}' entries in its first map but '3' was expected."); | ||
| } | ||
|
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.TextString) | ||
| { | ||
| throw new FormatException($"Attestation Statement's first key was of type '{state}' but '{CborReaderState.TextString}' was expected."); | ||
| } | ||
|
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| string label = cborReader.ReadTextString(); | ||
| if (label is not "fmt") | ||
| { | ||
| throw new FormatException($"Attestation Statement's first key was '{label}' but 'fmt' was expected."); | ||
| } | ||
|
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| state = cborReader.PeekState(); | ||
| if (state is not CborReaderState.TextString) | ||
| { | ||
| throw new FormatException($"Attestation Statement's first value was of type '{state}' but '{CborReaderState.TextString}' was expected."); | ||
| } | ||
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| string fmt = cborReader.ReadTextString(); | ||
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| return fmt switch | ||
| { | ||
| "packed" => PackedAttestationStatement.ReadAttestationStatement(cborReader), | ||
| "android-safetynet" => AndroidSafetyNetAttestationStatement.ReadAttestationStatement(cborReader), | ||
| _ => throw new FormatException($"Attestation Statement had format '{fmt}' which was not supported.") | ||
| }; | ||
| } | ||
| } |
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