SHA-1 is a cryptographic hash function that takes in an input and produces a fixed-size output known as a message digest. It generates a 160-bit hash value, which represents the input data in a unique manner. Therefore, Yes, a plaintext article can be encrypted using the SHA-1 algorithm to produce a fixed-size hash value as the output. However, please note that SHA-1 is now considered to be insecure and should not be used for new applications. It is recommended to use hashing algorithms such as SHA-256 or SHA-3 for better security.