RSA Security 5.2.2 manual Decrypting the Introductory Example, Creating the Key Object

Decrypting the Introductory Example

Decrypting the Introductory Example

Decrypting data is similar to encrypting. The RC4 cipher uses symmetric-key encryption, which means the key that was used to encrypt will be the key needed for decryption.

The example in this section corresponds to the file dintroex.c.

Step 1: Creating an Algorithm Object

First create the algorithm object.

B_ALGORITHM_OBJ rc4Decrypter = (B_ALGORITHM_OBJ)NULL_PTR;

if ((status = B_CreateAlgorithmObject (&rc4Decrypter)) != 0) break;

Step 2: Setting the Algorithm Object

Use the same AI and parameters as for encryption:

if ((status = B_SetAlgorithmInfo (rc4Decrypter, AI_RC4, NULL_PTR)) != 0)

break;

Step 3: Init

Use the same key data as for encryption. Once again, we must create and set the key object.

Step 3a: Creating the Key Object

As before, we name our key object rc4Key and declare it as follows:

B_KEY_OBJ rc4Key = (B_KEY_OBJ)NULL_PTR;

Then we allocate space for the key object using B_CreateKeyObject:

if ((status = B_CreateKeyObject (&rc4Key)) != 0) break;

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