This specification describes a JavaScript API for performing basic cryptographic operations in web applications, such as hashing, signature generation and verification, and encryption and decryption. Additionally, it describes an API for applications to generate and/or manage the keying material necessary to perform these operations. Uses for this API range from user or service authentication, document or code signing, and the confidentiality and integrity of communications.
The MD4, MD5 and SHA-1 algorithms are secure hash functions. They take a string input, and produce a fixed size number - 128 bits for MD4 and MD5; 160 bits for SHA-1.