SHA (Secure Hash Algorithm)

Developed by NIST (National Institute of Standard Technology)

The differences with MD5 is it generates 160 bits message digest or hash value.

SHA-1

SHA-192

SHA-256

SHA-1024

SHA-2080

How SHA Working !

Step 1 : Padding à Same as MD5

Step 2 : Append length à Same  as MD5

Step 3 : Divide into 512bits blocksà Same  as MD5

Step 4 : Initialize 5 chairing variable A,B,C,D,E

Step 5 : Processing of blocks

5.1 à copy this 5 chairing in step 4 into 5

a=A, b=B, c=C,  d=D , e=E

5.2à Devide every 512 bits block into corresponding 16 sub-blocks of 32 bits each

5.3 à  SHA has 4 rounds  à 20 steps à80 iteration

abdce= ( e + Process P + 55 (a) + W [t] + k[t], a, s30 (b), c,d)

COMPARISON OF MD5 & SHA

No.	MD5	SHA -1
Message digest in bits	128  bits	160 bits
Number of attacks to be performed to find out original message	2 128 operation	2160 operation
Speed	Faster	Slower

Hash Generation à to double check original content from the sender whether its modified or not.

Sender à Encrypted files + hash value MD5 or SHA ----------à  Receiver Decrypted files + hash value MD5 or SHA