Table of Contents

Class HmacMessageDigest5

Namespace
Cuemon.Security.Cryptography
Assembly
Cuemon.Security.Cryptography.dll

Provides a Hash-based Message Authentication Code (HMAC) by using the MD5 hash function. This class cannot be inherited. Implements the KeyedCryptoHash<TAlgorithm>

public sealed class HmacMessageDigest5 : KeyedCryptoHash<HMACMD5>, IHash, IConfigurable<ConvertibleOptions>
Inheritance
HmacMessageDigest5
Implements
Inherited Members

Examples

HmacMessageDigest5 computes and verifies HMAC-MD5 message authentication codes with support for custom byte order and direct string input. This example creates a 64-byte secret key, computes the HMAC of "Important: Transfer $100 to account 12345", then verifies it by recomputing with the same secret. A tampered message with a different account number produces a different HMAC, confirming tamper detection. It also demonstrates options-based construction with Endianness.LittleEndian and direct ComputeHash(string) overload. Console output shows the hex and base64 HMAC values, verification status (True), tamper detection (False), and options-based result.

using System;
using System.Text;
using Cuemon.Security;
using Cuemon.Security.Cryptography;

using Cuemon;
namespace MyApp.Security
{
    public static class HmacMessageDigest5Examples
    {
        public static void Demonstrate()
        {
            // Define a secret key (minimum 64 bytes recommended for HMAC-MD5).
            byte[] secret = Encoding.UTF8.GetBytes(
                "ThisIsASecretKeyThatShouldBeAtLeastSixtyFourBytesLongForBestResults1234567");

            // Create an HMAC-MD5 instance with the secret.
            var hmacMd5 = new HmacMessageDigest5(secret, null);

            // Compute the HMAC of a message.
            byte[] message = Encoding.UTF8.GetBytes("Important: Transfer $100 to account 12345");
            HashResult hash = hmacMd5.ComputeHash(message);

            Console.WriteLine("HMAC-MD5 (hex): {0}", hash.ToHexadecimalString());
            Console.WriteLine("HMAC-MD5 (base64): {0}", hash.ToBase64String());

            // Verify the HMAC by recomputing with the same secret.
            var verifier = new HmacMessageDigest5(secret, null);
            HashResult expected = verifier.ComputeHash(message);
            bool isValid = hash.Equals(expected);
            Console.WriteLine("HMAC valid: {0}", isValid); // true

            // Tampered message produces a different HMAC.
            byte[] tampered = Encoding.UTF8.GetBytes("Important: Transfer $100 to account 99999");
            HashResult tamperedHash = hmacMd5.ComputeHash(tampered);
            Console.WriteLine("Tampered HMAC matches: {0}", hash.Equals(tamperedHash)); // false

            // Compute HMAC from string directly (UTF-8 encoding by default).
            HashResult fromString = hmacMd5.ComputeHash("Hello, HMAC!");
            Console.WriteLine("String HMAC: {0}", fromString);
        }

        public static void DemonstrateWithOptions()
        {
            byte[] secret = Encoding.UTF8.GetBytes("my-secret-key");
            var hmacMd5 = new HmacMessageDigest5(secret, o =>
            {
                o.ByteOrder = Endianness.LittleEndian;
            });
            HashResult result = hmacMd5.ComputeHash(Encoding.UTF8.GetBytes("test data"));
            Console.WriteLine("HMAC-MD5 (little-endian): {0}", result.ToHexadecimalString());
        }
    }
}

Constructors

HmacMessageDigest5(byte[], Action<ConvertibleOptions>)

Initializes a new instance of the HmacMessageDigest5 class.

public HmacMessageDigest5(byte[] secret, Action<ConvertibleOptions> setup)

Parameters

secret byte[]

The secret key for HmacMessageDigest5 encryption. The key can be any length, but if it is more than 64 bytes long it will be hashed (using SHA-1) to derive a 64-byte key. Therefore, the recommended size of the secret key is 64 bytes.

setup Action<ConvertibleOptions>

The ConvertibleOptions which need to be configured.

See Also

Hash<TOptions>
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