SHA- 1 and MD5 are abstract algorithms, and they are irreversible.

From the application point of view, applicability is more important than security. The lengths of the two algorithms are different, SHA- 1 160 bits and MD5 128 bits.

From the security point of view, if you sign the abstract after calculation, you can increase your ability to resist denial and tampering. For more information, see Digital Signature Information.