A method for side-channel attack mitigation in streaming encryption includes reading an input stream into a decryption process, extracting an encryption envelope having a wrapped key, a cipher text, and a first message authentication code (MAC) from the input stream, generating a second MAC using the wrapped key of the encryption envelope, and performing decryption of the cipher text in constant time by determining whether the encryption envelope is authentic by comparing the first MAC extracted from the encryption envelope and the second MAC generated using the wrapped key.