RSA Security Projection Television 5.2.2 Manual de usuario descargar pdf (Pagina 250)

MultiPrime

228 RSA BSAFE Crypto-C Developer’s Guide

You are encrypting 8 bytes, so you do not need to worry about that constraint.

However, the output of RSA encryption is the same size as the modulus, as described

in “The RSA Algorithm” on page 51. That means you must set the output buffer,

which will hold the encrypted data, to be the same size as the modulus. Your

modulus is 512 bits, or 64 bytes.

Note: The input to the RSA algorithm must also be the same size as the modulus,

but

AI_PKCS_RSAPublic will automatically pad.

The description of

AI_PKCS_RSAPublic notes that “B_EncryptUpdate and

B_EncryptFinal require a random algorithm.” The random number generator is for

the padding. You do not need random bytes, only an algorithm that can generate

them. Although RSA encryption is not as slow as key pair generation, you will not see

an immediate response. Use a surrender context so that you know the program is

running and has not frozen:

Step 5: Final

#define BLOCK_SIZE 64

unsigned char encryptedData[BLOCK_SIZE];

unsigned int outputLenUpdate;

/* generalFlag is for the surrender function.*/

generalFlag = 0;

if ((status = B_EncryptUpdate

(rsaEncryptor, encryptedData, &outputLenUpdate,

BLOCK_SIZE, (unsigned char *)dataToEncryptWithRSA, 8,

randomAlgorithm, (A_SURRENDER_CTX*)NULL_PTR)) != 0)

break;

unsigned int outputLenFinal;

/* generalFlag is for the surrender function.*/

generalFlag = 0;

if ((status = B_EncryptFinal

(rsaEncryptor, encryptedData + outputLenUpdate,

&outputLenFinal, BLOCK_SIZE - outputLenUpdate,

randomAlgorithm, (A_SURRENDER_CTX*)NULL_PTR)) != 0)

break;

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RSA Security Projection Television 5.2.2 Manual de usuario Pagina 250