Aug 03, 2012 · 2) Each block of RSA encrypted data has size equal to the key modulus (in bytes). This means that for a key size of 1024 bits you need to read 128 bytes and not 64 bytes at a time when decrypting ( this is probably the cause of your 'Data must start with zero exception').

1.Most widely accepted and implemented general purpose approach to public key encryption developed by Rivest-Shamir and Adleman (RSA) at MIT university. 2.RSA scheme is block cipher in which the plaintext and ciphertext are integers between 0 and n-1 for same n. 3.Typical size of n is 1024 bits. i.e n<2. 4.Description of Algorithm: For OAEP padding, recommended for all new applications, it must be less than the size of the key modulus – 41 (all in bytes). To get the size of the modulus of an RSA key call the function RSA_size. The modulus size is the key size in bits / 8. Thus a 1024-bit RSA key using OAEP padding can encrypt up to (1024/8) – 42 = 128 – 42 = 86 bytes. RSA ® Business-Driven Security™ solutions address critical risks that organizations across sectors are encountering as they weave digital technologies deeper into their businesses. Cyber attacks See how prioritizing threats can help your organization coordinate an effective response to cyber attacks that helps minimize business impact. I have a 2048 bit key. From your original post, it appears that the blocksize for encrypting should be the same as the blocksize for decrypting, but my professor told us this isn't the case. RSA encryption usually is only used for messages that fit into one block. A 1024-bit RSA key invocation can encrypt a message up to 117 bytes, and results in a 128-byte value A 2048-bit RSA key invocation can encrypt a message up to 245 bytes

## It uses a 128-bit block size and various key lengths (128, 192, 256). Triple DES 3DES Symmetric cipher that applies DES three times to each block of data during the encryption process.

In practice this is sufficient because RSA is commonly used to only encrypt a symmetric encryption key, which is much smaller than the RSA key size . The scheme can work well enough for arbitrary sized messages though - we'll just split it to multiple blocks with some pre-determined block size. The RSA cipher requires the block size to be equal to or less than the key size. Either increase the block size or use different keys.' % (blockSize * 8, keySize)) In order for the mathematics of the RSA cipher to work, the key size must be equal to or greater than the block size. If the input text is divided into a fixed block size for encryption and decryption, what could be the typical block size for RSA algorithm for different size of input like 8 MB, 16 MB, 126 MB and 2

### A common asymmetric key algorithm is RSA. The term block size refers to the block cipher. Basically, there are 2 types of ciphers. Stream cipher - The algorithm encrypts/decrypts the message 1 bit at a time. Block cipher - The algorithm encrypts/decrypts the message block by block, a block referring to a group of bits. Common block ciphers

1.Most widely accepted and implemented general purpose approach to public key encryption developed by Rivest-Shamir and Adleman (RSA) at MIT university. 2.RSA scheme is block cipher in which the plaintext and ciphertext are integers between 0 and n-1 for same n. 3.Typical size of n is 1024 bits. i.e n<2. 4.Description of Algorithm: