Oct 04, 2013 I need to generate a md5 hash for given string. It will be used by shell script to generate keys for remote web service or cryptographic application. How do I generate a md5 hash based on any input string under Linux or Unix like operating systems? You can use md5sum command to compute and check MD5 message digest. This is a default tool on. Rainbow tables with words and hashes generated allows searching very quickly for a known hash and getting the original word. MD5 is not collision resistant which means that different passwords can eventually result in the same hash. Today, if you are using MD5 hash in your application then consider adding some salt to your security.
-->Definition
Represents the abstract class from which all implementations of the MD5 hash algorithm inherit.
- Derived
- Attributes
Examples
The following code example computes the MD5 hash value of a string and returns the hash as a 32-character, hexadecimal-formatted string. The hash string created by this code example is compatible with any MD5 hash function (on any platform) that creates a 32-character, hexadecimal-formatted hash string.
Remarks
Hash functions map binary strings of an arbitrary length to small binary strings of a fixed length. A cryptographic hash function has the property that it is computationally infeasible to find two distinct inputs that hash to the same value; that is, hashes of two sets of data should match if the corresponding data also matches. Small changes to the data result in large, unpredictable changes in the hash.
The hash size for the MD5 algorithm is 128 bits.
The ComputeHash methods of the MD5 class return the hash as an array of 16 bytes. Note that some MD5 implementations produce a 32-character, hexadecimal-formatted hash. To interoperate with such implementations, format the return value of the ComputeHash methods as a hexadecimal value.
Note
Due to collision problems with MD5/SHA1, Microsoft recommends SHA256 or SHA512. Consider using the SHA256 class or the SHA512 class instead of the MD5 class. Use MD5 only for compatibility with legacy applications and data.
Constructors
| MD5() | Initializes a new instance of MD5. |
Fields
| HashSizeValue | Represents the size, in bits, of the computed hash code. (Inherited from HashAlgorithm) |
| HashValue | Represents the value of the computed hash code. (Inherited from HashAlgorithm) |
| State | Represents the state of the hash computation. (Inherited from HashAlgorithm) |
Properties
| CanReuseTransform | Gets a value indicating whether the current transform can be reused. (Inherited from HashAlgorithm) |
| CanTransformMultipleBlocks | When overridden in a derived class, gets a value indicating whether multiple blocks can be transformed. (Inherited from HashAlgorithm) |
| Hash | Gets the value of the computed hash code. (Inherited from HashAlgorithm) |
| HashSize | Gets the size, in bits, of the computed hash code. (Inherited from HashAlgorithm) |
| InputBlockSize | When overridden in a derived class, gets the input block size. (Inherited from HashAlgorithm) |
| OutputBlockSize | When overridden in a derived class, gets the output block size. (Inherited from HashAlgorithm) |
Methods
| Clear() | Releases all resources used by the HashAlgorithm class. (Inherited from HashAlgorithm) |
| ComputeHash(Byte[]) | Computes the hash value for the specified byte array. (Inherited from HashAlgorithm) |
| ComputeHash(Byte[], Int32, Int32) | Computes the hash value for the specified region of the specified byte array. (Inherited from HashAlgorithm) |
| ComputeHash(Stream) | Computes the hash value for the specified Stream object. (Inherited from HashAlgorithm) |
| ComputeHashAsync(Stream, CancellationToken) | (Inherited from HashAlgorithm) |
| Create() | Creates an instance of the default implementation of the MD5 hash algorithm. |
| Create(String) | Creates an instance of the specified implementation of the MD5 hash algorithm. |
| Dispose() | Releases all resources used by the current instance of the HashAlgorithm class. (Inherited from HashAlgorithm) |
| Dispose(Boolean) | Releases the unmanaged resources used by the HashAlgorithm and optionally releases the managed resources. (Inherited from HashAlgorithm) |
| Equals(Object) | Determines whether the specified object is equal to the current object. (Inherited from Object) |
| GetHashCode() | Serves as the default hash function. (Inherited from Object) |
| GetType() | Gets the Type of the current instance. (Inherited from Object) |
| HashCore(Byte[], Int32, Int32) | When overridden in a derived class, routes data written to the object into the hash algorithm for computing the hash. (Inherited from HashAlgorithm) |
| HashCore(ReadOnlySpan<Byte>) | Routes data written to the object into the hash algorithm for computing the hash. (Inherited from HashAlgorithm) |
| HashFinal() | When overridden in a derived class, finalizes the hash computation after the last data is processed by the cryptographic hash algorithm. (Inherited from HashAlgorithm) |
| Initialize() | Resets the hash algorithm to its initial state. (Inherited from HashAlgorithm) |
| MemberwiseClone() | Creates a shallow copy of the current Object. (Inherited from Object) |
| ToString() | Returns a string that represents the current object. (Inherited from Object) |
| TransformBlock(Byte[], Int32, Int32, Byte[], Int32) | Computes the hash value for the specified region of the input byte array and copies the specified region of the input byte array to the specified region of the output byte array. (Inherited from HashAlgorithm) |
| TransformFinalBlock(Byte[], Int32, Int32) | Computes the hash value for the specified region of the specified byte array. (Inherited from HashAlgorithm) |
| TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32) | Attempts to compute the hash value for the specified byte array. (Inherited from HashAlgorithm) |
| TryHashFinal(Span<Byte>, Int32) | Attempts to finalize the hash computation after the last data is processed by the hash algorithm. (Inherited from HashAlgorithm) |
Explicit Interface Implementations
| IDisposable.Dispose() | Releases the unmanaged resources used by the HashAlgorithm and optionally releases the managed resources. (Inherited from HashAlgorithm) |
Applies to
See also
-->It is a common practice to store passwords in databases using a hash. MD5 (defined in RFC 1321) is a common hash algorithm, and using it from C# is easy.
Here’s an implementation of a method that converts a string to an MD5 hash, which is a 32-character string of hexadecimal numbers.
An example call:
…returns a string like this:
Using Md5 Hash To Generate A Key Number
To make the hex string use lower-case letters instead of upper-case, replace the single line inside the for loop with this line:
The difference is the ToString method parameter.
Using Md5 Hash To Generate A Key Code
[author: Jani Järvinen, C# MVP]