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time with no significant change in security, because the RSA algorithm will be

sufficiently safe against brute force attack, especially with the length of the key is

256 bits.

Figure 19 shows the enc/dec process for AES key using RSA, where the RSA

decryption is not as effective as the encryption process [35] that the decryption

process took much more time than the encryption process time, otherwise ECC has

shown better efficiency and security than RSA, so we are using ECC, the ECC is

slow in encryption, but it is faster in decryption [35]. We have to remember that the

security aspect of ECC is much better than RSA, as the ECC with a key length of

256 bits equals the same level of security in RSA with a key length of 3072 bits. The

increase in the key length in RSA to achieve the same level of security in ECC leads

to an increase in time, memory and energy consumed, thus becoming Relying on

the ECC algorithm with an oval curve is very important because its implementation

requires less storage and calculations and hence better, and this is why we rely on

ECC as a significant improvement in our research [31]. Table 3 gives us the equivalent

security level of RSA and ECC key size.

Security has been improved by generating hash from three factors (Data, Times-

tamp, and previous hash) instead of only data, with very little difference in

performance time, as shown in Fig. 20.

Fig. 19 Encryption/decryption process for AES key using RSA

Table 3 RSA and ECC key size for equivalent security level [31]

Security level Lk, where Lk presents the length of a

symmetric key k

80

112

128

192

256

ECC key length (bits)

160

224

256

384

512

RSA key length (bits)

1024

2048

3072

7680

15,360