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[Cryptography] Add algorithm stubs
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‎src/Amazon.Cryptography/Algorithms/AES256_GCM_HKDF_SHA512_COMMIT_KEY.cs‎

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using System.Buffers.Binary;
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using System.Security.Cryptography;
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namespace Amazon.Cryptography.Algorithms;
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internal sealed class AES256_GCM_HKDF_SHA512_COMMIT_KEY : AlgorithmSuite
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{
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public static readonly AES256_GCM_HKDF_SHA512_COMMIT_KEY Default = new();
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public override AlgorithmSuiteId AlgorithmId => AlgorithmSuiteId.AES_256_GCM_HKDF_SHA512_COMMIT_KEY;
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public override byte MessageFormatVersion => 0x02;
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public override KeySize DataKeyLength => KeySize.FromBitCount(256);
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public override int AlgorithmSuiteDataLengthBytes => 32;
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public override KeyDerivationAlgorithmType? KeyDerivationAlgorithm => KeyDerivationAlgorithmType.HKDF_SHA512;
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public EncryptedMessage Encrypt(DataKey key, EncryptMessageRequest request)
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{
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if (key.RawKey.Length != 32)
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{
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throw new ArgumentException("Key must be 32 bytes (256 bits)", nameof(key));
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}
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var messageId = RandomNumberGenerator.GetBytes(32); // 256 bits
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// Derive a key using HKDF
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Span<byte> derivedKey = stackalloc byte[32];
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DeriveKey(key.RawKey, messageId, derivedKey);
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using var aes = new AesGcm(derivedKey, 16);
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Span<byte> iv = stackalloc byte[12]; // 12-byte IV for AES-GCM
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Span<byte> tag = stackalloc byte[16]; // 16-byte authentication tag
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tag.Clear();
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byte[] associatedData = request.EncryptionContext.Serialize();
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(long chuckCount, long r) = Math.DivRem(request.Plaintext.Length, request.FrameLength);
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if (r > 0) chuckCount++;
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var frames = new List<EncryptedMessageFrame>((int)chuckCount);
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uint sequenceNumber = 1;
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int offset = 0;
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int frameLength = (int)request.FrameLength;
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ReadOnlySpan<byte> plaintext = request.Plaintext;
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while (offset < plaintext.Length)
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{
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var chunk = plaintext.Slice(offset, Math.Min(frameLength, plaintext.Length - offset));
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SetIV(sequenceNumber, iv);
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byte[] ciphertext = new byte[chunk.Length];
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aes.Encrypt(iv, chunk, ciphertext, tag, associatedData);
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var frame = new EncryptedMessageFrame {
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IV = iv.ToArray(),
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EncryptedContent = ciphertext,
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SequenceNumber = sequenceNumber,
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AuthenticationTag = tag.ToArray(),
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IsFinal = sequenceNumber == chuckCount,
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};
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sequenceNumber++;
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offset += chunk.Length;
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frames.Add(frame);
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}
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return new EncryptedMessage {
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Header = new EncryptedMessageHeader {
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AlgorithmId = AlgorithmId,
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AlgorithmSuiteData = messageId,
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MessageId = messageId,
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ContentType = 2, // framed
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EncryptionContext = request.EncryptionContext,
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AuthenticationTag = "a"u8.ToArray(),
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EncryptedDataKeys = [
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new EncryptedDataKey(key.ProviderId, key.ProviderContext, [])
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],
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FrameLength = request.FrameLength,
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Version = 2
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},
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Frames = frames
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};
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}
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public override void DeriveKey(ReadOnlySpan<byte> dataKey, ReadOnlySpan<byte> messageId, Span<byte> derivedKey)
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{
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if (messageId.Length != 32)
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{
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throw new ArgumentException("Must be 32 bytes (256 bits)", nameof(dataKey));
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}
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if (messageId.Length != 32)
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{
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throw new CryptographicException("Must be 32 bytes (256 bits)");
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}
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if (derivedKey.Length != 32)
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{
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throw new ArgumentException("Must be 32 bytes (256 bits)", nameof(derivedKey));
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}
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Span<byte> inputInfo = stackalloc byte[
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2 + // algorithmId
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9 // key label
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];
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BinaryPrimitives.WriteUInt16BigEndian(inputInfo, (ushort)AlgorithmId);
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"DERIVEKEY"u8.CopyTo(inputInfo[2..]);
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HKDF.DeriveKey(HashAlgorithmName.SHA512, dataKey, derivedKey, salt: messageId, inputInfo);
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}
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public void CalculateCommitmentKey(ReadOnlySpan<byte> dataKey, ReadOnlySpan<byte> messageId, Span<byte> commitmentKey)
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{
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HKDF.DeriveKey(HashAlgorithmName.SHA512, dataKey, commitmentKey, salt: messageId, info: "COMMITKEY"u8);
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}
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private static void SetIV(uint sequenceNumber, Span<byte> iv)
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{
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iv.Clear();
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BinaryPrimitives.WriteUInt32BigEndian(iv[8..], sequenceNumber);
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}
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}

‎src/Amazon.Cryptography/Algorithms/AES_256_GCM_HKDF_SHA512_COMMIT_KEY_ECDSA_P384.cs‎

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using System.Buffers.Binary;
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using System.Security.Cryptography;
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namespace Amazon.Cryptography.Algorithms;
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internal sealed class AES_256_GCM_HKDF_SHA512_COMMIT_KEY_ECDSA_P384 : AlgorithmSuite
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{
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public static readonly AES_256_GCM_HKDF_SHA512_COMMIT_KEY_ECDSA_P384 Default = new();
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public override AlgorithmSuiteId AlgorithmId => AlgorithmSuiteId.AES_256_GCM_HKDF_SHA512_COMMIT_KEY_ECDSA_P384;
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public override byte MessageFormatVersion => 0x02;
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public override KeySize DataKeyLength => KeySize.FromBitCount(256);
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public override int AlgorithmSuiteDataLengthBytes => 32;
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public override KeyDerivationAlgorithmType? KeyDerivationAlgorithm => KeyDerivationAlgorithmType.HKDF_SHA512;
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public EncryptedMessage Encrypt(DataKey key, EncryptMessageRequest request)
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{
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if (key.RawKey.Length != 32)
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{
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throw new ArgumentException("Key must be 32 bytes (256 bits)", nameof(key));
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}
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var messageId = RandomNumberGenerator.GetBytes(32); // 256 bits
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// Derive a key using HKDF
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Span<byte> derivedKey = stackalloc byte[32];
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DeriveKey(key.RawKey, messageId, derivedKey);
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using var aes = new AesGcm(derivedKey, 16);
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Span<byte> iv = stackalloc byte[12]; // 12-byte IV for AES-GCM
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Span<byte> tag = stackalloc byte[16]; // 16-byte authentication tag
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tag.Clear();
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byte[] associatedData = request.EncryptionContext.Serialize();
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(long chuckCount, long r) = Math.DivRem(request.Plaintext.Length, request.FrameLength);
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if (r > 0) chuckCount++;
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var frames = new List<EncryptedMessageFrame>((int)chuckCount);
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uint sequenceNumber = 1;
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int offset = 0;
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int frameLength = (int)request.FrameLength;
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ReadOnlySpan<byte> plaintext = request.Plaintext;
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while (offset < plaintext.Length)
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{
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var chunk = plaintext.Slice(offset, Math.Min(frameLength, plaintext.Length - offset));
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SetIV(sequenceNumber, iv);
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byte[] ciphertext = new byte[chunk.Length];
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aes.Encrypt(iv, chunk, ciphertext, tag, associatedData);
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var frame = new EncryptedMessageFrame {
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IV = iv.ToArray(),
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EncryptedContent = ciphertext,
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SequenceNumber = sequenceNumber,
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AuthenticationTag = tag.ToArray(),
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IsFinal = sequenceNumber == chuckCount,
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};
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sequenceNumber++;
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offset += chunk.Length;
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frames.Add(frame);
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}
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return new EncryptedMessage {
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Header = new EncryptedMessageHeader {
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AlgorithmId = AlgorithmId,
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AlgorithmSuiteData = messageId,
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MessageId = messageId,
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ContentType = 2, // framed
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EncryptionContext = request.EncryptionContext,
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AuthenticationTag = "a"u8.ToArray(),
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EncryptedDataKeys = [
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new EncryptedDataKey(key.ProviderId, key.ProviderContext, [])
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],
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FrameLength = request.FrameLength,
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Version = 2
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},
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Frames = frames
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};
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}
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public override void DeriveKey(ReadOnlySpan<byte> dataKey, ReadOnlySpan<byte> messageId, Span<byte> derivedKey)
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{
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if (messageId.Length != 32)
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{
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throw new ArgumentException("Must be 32 bytes (256 bits)", nameof(dataKey));
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}
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if (messageId.Length != 32)
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{
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throw new CryptographicException("Must be 32 bytes (256 bits)");
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}
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if (derivedKey.Length != 32)
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{
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throw new ArgumentException("Must be 32 bytes (256 bits)", nameof(derivedKey));
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}
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Span<byte> inputInfo = stackalloc byte[
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2 + // algorithmId
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9 // key label
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];
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BinaryPrimitives.WriteUInt16BigEndian(inputInfo, (ushort)AlgorithmId);
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"DERIVEKEY"u8.CopyTo(inputInfo[2..]);
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HKDF.DeriveKey(HashAlgorithmName.SHA512, dataKey, derivedKey, salt: messageId, inputInfo);
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}
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public void CalculateCommitmentKey(ReadOnlySpan<byte> dataKey, ReadOnlySpan<byte> messageId, Span<byte> commitmentKey)
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{
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HKDF.DeriveKey(HashAlgorithmName.SHA512, dataKey, commitmentKey, salt: messageId, info: "COMMITKEY"u8);
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}
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private static void SetIV(uint sequenceNumber, Span<byte> iv)
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{
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iv.Clear();
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BinaryPrimitives.WriteUInt32BigEndian(iv[8..], sequenceNumber);
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}
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// TODO: Implement signature logic
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}

‎src/Amazon.Cryptography/Algorithms/AlgorithmSuite.Factory.cs‎

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namespace Amazon.Cryptography.Algorithms;
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public partial class AlgorithmSuite
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{
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public static AlgorithmSuite Get(AlgorithmSuiteId id)
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{
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return id switch {
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AlgorithmSuiteId.AES_256_GCM_HKDF_SHA512_COMMIT_KEY => AES256_GCM_HKDF_SHA512_COMMIT_KEY.Default,
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AlgorithmSuiteId.AES_256_GCM_HKDF_SHA512_COMMIT_KEY_ECDSA_P384 => AES_256_GCM_HKDF_SHA512_COMMIT_KEY_ECDSA_P384.Default,
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_ => throw new NotImplementedException()
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};
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}
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}

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