![]() However, the TypeScript implementation was significantly more difficult due to its limited support for low-level bitwise operations, in particular with working with integers. I referred to the RFC for guidance both times, and it was fairly straightforward to implement. I’ve implemented SHA-1 twice, once in TypeScript for my authenticator app, and once in Rust as part of my implementation of the WebSocket protocol. This continues until all chunks have been processed, and finally, the five state variables are combined into a single 160-bit hash value. These values are then used to generate some further values by performing eighty rounds of bitwise operations based on the chunk values. Five state variables are assigned specific starting values as follows: h0 = 0圆7452301 Each chunk is then further broken down into sixteen 32-bit integers, which are used to generate additional integers using bitwise operations to bring this number up to eighty. RFC 3174 is a useful resource to explore the algorithm further and refer to for implementation, as it contains the text of the original document defining SHA-1.Īfter some pre-processing to ensure that the input is a multiple of 64 bytes by way of padding, the input is split into chunks of 64 bytes or 512 bits. I’m not an expert in cryptography, but I’ll do my best to explain the basics of the algorithm. A vital property of a hash function is that the same input will produce the same output, and that the probability of two different inputs producing the same output (a “collision”) is almost impossible. ![]() A hash function takes a variable-length string of bytes, performs a number of one-way operations on them, often over a number of iterations, then produces a fixed-length string of bytes. ![]() SHA-1 HashingĪt the heart of the algorithm is the SHA-1 cryptographic hash function. If successful, the authentication process is complete and the server can supply the user with a token or something else. This key, along with the current time, is used each time the user generates a code, and the server uses the same key and the current time to independently verify the code. When 2FA is first set up, the server generates a secret key and shares it with the client in the form of a QR code, which the client scans using an authenticator app, such as Authenticate. When a user wants to authenticate with a server using two-factor authentication, they need to enter their password as well as a one-time code generated by the TOTP algorithm. This was the topic of my Exeter Mathematics Certificate research project, so you can read a more academic write-up in my report if you’re interested. In this blog post, I’ll be discussing the algorithms that make up the time-based one-time password two-factor authentication (TOTP). But how does it actually work behind the scenes? By requiring a secondary code to be generated locally and entered when signing in, the account is protected even in the event of a compromised password. Two-factor authentication is a vital part of securing any account.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |