====== Signatures Namespace ======

**Namespace:** ''WvdS.System.Security.Cryptography.Signatures''

Contains extension methods for digital signatures with PQ support.

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===== Classes =====

^  Class  ^  Description  ^
| SignatureExtensions | Extensions for RSA, ECDsa, and X509Certificate2 signatures |
| SignedDataExtensions | Extensions for CMS/PKCS#7 SignedCms |
| HybridSignatureInfo | Container for hybrid signature data |
| PqSignedCmsHelper | High-level API for PQ-capable CMS operations |

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===== Extended Types =====

^  .NET Type  ^  Extension Class  ^
| ''System.Security.Cryptography.RSA''((Microsoft Docs: https://learn.microsoft.com/dotnet/api/system.security.cryptography.rsa)) | SignatureExtensions |
| ''System.Security.Cryptography.ECDsa''((Microsoft Docs: https://learn.microsoft.com/dotnet/api/system.security.cryptography.ecdsa)) | SignatureExtensions |
| ''System.Security.Cryptography.Pkcs.SignedCms''((Microsoft Docs: https://learn.microsoft.com/dotnet/api/system.security.cryptography.pkcs.signedcms)) | SignedDataExtensions |

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===== Signature Modes =====

| Mode | Classic | ML-DSA | Usage |
| Classic | Yes | - | Standard .NET behavior |
| Hybrid | Yes | Yes | Maximum security |
| PostQuantum | - | Yes | Pure post-quantum |

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===== Hybrid Signature Format =====

In Hybrid mode, two signatures are created:

<code>
+------------------------------------------+
| Hybrid Signature                         |
+------------------------------------------+
| [4 Bytes] Length of classic signature    |
| [n Bytes] Classic signature (RSA/ECDSA)  |
| [m Bytes] PQ signature (ML-DSA)          |
+------------------------------------------+
</code>

^ Component ^ Typical Size ^
| RSA-2048 signature | 256 bytes |
| ECDSA P-256 signature | ~70 bytes |
| ML-DSA-65 signature | 3,293 bytes |
| **Hybrid RSA** | **~3,553 bytes** |

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===== Example =====

<code csharp>
using WvdS.System.Security.Cryptography;
using WvdS.System.Security.Cryptography.Signatures;

CryptoConfig.DefaultMode = CryptoMode.Hybrid;

using var rsa = RSA.Create(2048);
byte[] data = Encoding.UTF8.GetBytes("Data to sign");

// Create hybrid signature
byte[] signature = rsa.SignData(
    data,
    HashAlgorithmName.SHA256,
    RSASignaturePadding.Pkcs1);

// Verify
bool valid = rsa.VerifyData(
    data,
    signature,
    HashAlgorithmName.SHA256,
    RSASignaturePadding.Pkcs1);
</code>

----

===== SignatureExtensions Methods =====

==== RSA Extensions ====

^ Method ^ Parameters ^ Return ^
| ''SignData(data, hash, padding, mode)'' | byte[], HashAlgorithmName, RSASignaturePadding, CryptoMode? | byte[] |
| ''SignData(stream, hash, padding, mode)'' | Stream, HashAlgorithmName, RSASignaturePadding, CryptoMode? | byte[] |
| ''VerifyData(data, sig, hash, padding, mode)'' | byte[], byte[], HashAlgorithmName, RSASignaturePadding, CryptoMode? | bool |

==== ECDsa Extensions ====

^ Method ^ Parameters ^ Return ^
| ''SignData(data, hash, mode)'' | byte[], HashAlgorithmName, CryptoMode? | byte[] |
| ''VerifyData(data, sig, hash, mode)'' | byte[], byte[], HashAlgorithmName, CryptoMode? | bool |

==== Standalone ML-DSA ====

^ Method ^ Parameters ^ Return ^
| ''GenerateMlDsaKeyPair()'' | - | (byte[] PublicKey, byte[] PrivateKey) |
| ''SignMlDsa(data, privateKey)'' | byte[], byte[] | byte[] |
| ''VerifyMlDsa(data, sig, publicKey)'' | byte[], byte[], byte[] | bool |

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===== See Also =====

  * [[.:x509certificates:start|X509Certificates Namespace]]
  * [[.:keyexchange|KeyExchange Namespace]]
  * [[.:start|API Overview]]

{{tag>namespace signatures ml-dsa}}

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//Wolfgang van der Stille @ EMSR DATA d.o.o. - Post-Quantum Cryptography Professional//