What is the authenticity of the Hadith: "In the name of Allah, I have veiled myself; and by the power of Allah, I have sought protection. So, whoever intends me ill or plots against me with a scheme is, by Allah's permission, forbidden [from reaching me] and repelled"?

No Hadith (definition) with this exact wording has been found, although its meaning is acceptable. It is authentically reported that the Prophet, peace and blessings be upon him, said: "No servant says, every morning and every night, 'In the name of Allah, with Whose Name nothing on earth or in heaven can cause harm, and He is the All-Hearing, the All-Knowing,' three times, except that nothing will harm him." The authentically reported prophetic supplications (adhkar) are sufficient and render others unnecessary.