Decrypt will use the given key, iv, and ciphertext and return the plaintext bytes.

Decrypt is a function that decrypts a given cipher text with a provided key and initialization vector(iv).

Encrypt will use the given iv, key, and plaintext bytes and return ciphertext bytes.

Encrypt is a function that encrypts plaintext with a given key and an optional initialization vector(iv).

ErrInvalidBlockSize indicates hash blocksize <= 0.

ErrInvalidPKCS7Data indicates bad input to PKCS7 pad or unpad.

ErrInvalidPKCS7Padding indicates PKCS7 unpad fails to bad input.