Windows Default Key Generation Algorithm Calg Md5

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Important This API is deprecated. New and existing software should start using Cryptography Next Generation APIs. Microsoft may remove this API in future releases.
The

RSA public key signature algorithm. Key length: Can be set, 384 bits to 16,384 bits in 8-bit increments. Default key length: 1,024 bits. Signature conforms to PKCS #6. CALGSHA: SHA hashing algorithm. For more information, see Secure Hash Algorithm. CALGSHA1: Same as CALGSHA. For more information, see Secure Hash Algorithm. CALGSHA256: SHA. Apr 28, 2014  Insufficient entropy in key generation algorithm #2. Open jaydansand opened this issue Apr 28, 2014 0 comments Open Insufficient entropy in key generation algorithm #2. Jaydansand opened this issue Apr 28, 2014 0 comments Comments. At least on Windows.

CryptCreateHash function initiates the hashing of a stream of data. It creates and returns to the calling application a handle to a cryptographic service provider (CSP) hash object. This handle is used in subsequent calls to CryptHashData and CryptHashSessionKey to hash session keys and other streams of data.

Syntax

Parameters

hProv

A handle to a CSP created by a call toCryptAcquireContext.

Algid

An ALG_ID value that identifies the hash algorithm to use.

Valid values for this parameter vary, depending on the CSP that is used. For a list of default algorithms, see Remarks.

hKey

If the type of hash algorithm is a keyed hash, such as the Hash-Based Message Authentication Code (HMAC) or Message Authentication Code (MAC) algorithm, the key for the hash is passed in this parameter. For nonkeyed algorithms, this parameter must be set to zero.

For keyed algorithms, the key must be to a block cipher key, such as RC2, that has a cipher mode of Cipher Block Chaining (CBC).

dwFlags

The following flag value is defined.

ValueMeaning
CRYPT_SECRETDIGEST
0x00000001
This flag is not used.

phHash

The address to which the function copies a handle to the new hash object. When you have finished using the hash object, release the handle by calling the CryptDestroyHash function.

Return value

If the function succeeds, the function returns TRUE.

If the function fails, it returns FALSE. For extended error information, callGetLastError.

The error codes prefaced by NTE are generated by the particular CSP you are using. The following table shows some of the possible error codes.

Return codeDescription
ERROR_INVALID_HANDLE
One of the parameters specifies a handle that is not valid.
ERROR_INVALID_PARAMETER
One of the parameters contains a value that is not valid. This is most often a pointer that is not valid.
ERROR_NOT_ENOUGH_MEMORY
The operating system ran out of memory during the operation.
NTE_BAD_ALGID
The Algid parameter specifies an algorithm that this CSP does not support.
NTE_BAD_FLAGS
The dwFlags parameter is nonzero.
NTE_BAD_KEY
A keyed hash algorithm, such as CALG_MAC, is specified by Algid, and the hKey parameter is either zero or it specifies a key handle that is not valid. This error code is also returned if the key is to a stream cipher or if the cipher mode is anything other than CBC.
NTE_NO_MEMORY
The CSP ran out of memory during the operation.

Remarks

For a list of Microsoft service providers and the algorithms they implement, see Microsoft Cryptographic Service Providers.

The computation of the actual hash is done with theCryptHashData andCryptHashSessionKey functions. These require a handle to the hash object. After all the data has been added to the hash object, any of the following operations can be performed:

  • The hash value can be retrieved by using CryptGetHashParam.
  • A session key can be derived by using CryptDeriveKey.
  • The hash can be signed by using CryptSignHash.
  • A signature can be verified by using CryptVerifySignature.
After one of the functions from this list has been called, CryptHashData and CryptHashSessionKey cannot be called.

Examples

The following example shows initiating the hashing of a stream of data. It creates and returns to the calling application a handle to a hash object. This handle is used in subsequent calls toCryptHashData andCryptHashSessionKey to hash any stream of data. For an example that includes the complete context for this example, seeExample C Program: Creating and Hashing a Session Key.For another example that uses this function, see Example C Program: Signing a Hash and Verifying the Hash Signature.

Requirements

Minimum supported clientWindows XP [desktop apps only]
Minimum supported serverWindows Server 2003 [desktop apps only]
Target PlatformWindows
Headerwincrypt.h
LibraryAdvapi32.lib
DLLAdvapi32.dll

See also

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The following example creates and hashes a session key that can be used to encrypt a message, text, or file.

Windows Default Key Generation Algorithm Calg Md5 File

This example also shows using the following CryptoAPI functions:

  • CryptAcquireContext to acquire a cryptographic service provider.
  • CryptCreateHash to create an empty hash object.
  • CryptGenKey to create a random session key.
  • CryptHashSessionKey to hash the session key created.
  • CryptDestroyHash to destroy the hash.
  • CryptDestroyKey to destroy the key created.
  • CryptReleaseContext to release the CSP.

This example uses the function MyHandleError. The code for this function is included with the sample. Code for this and other auxiliary functions is also listed under General Purpose Functions.