json_web_token v0.2.1 → Overview → JsonWebToken → Algorithm → Hmac

JsonWebToken.Algorithm.Hmac

Sign or verify a JSON Web Signature (JWS) structure using HMAC with SHA-2 algorithms

see http://tools.ietf.org/html/rfc7518#section-3.2

Summary↑

sign(sha_bits, shared_key, signing_input)

Return a Message Authentication Code (MAC)
verify?(mac, sha_bits, shared_key, signing_input)

Predicate to verify the signing_input by comparing a given mac to the mac for a newly signed message; comparison done in a constant-time manner to thwart timing attacks

Functions

sign(sha_bits, shared_key, signing_input)
(function) # ↑

Return a Message Authentication Code (MAC)

Example

iex> shared_key = "gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr9C"
...> JsonWebToken.Algorithm.Hmac.sign(:sha256, shared_key, "signing_input")
<<90, 34, 44, 252, 147, 130, 167, 173, 86, 191, 247, 93, 94, 12, 200, 30, 173, 115, 248, 89, 246, 222, 4, 213, 119, 74, 70, 20, 231, 194, 104, 103>>
verify?(mac, sha_bits, shared_key, signing_input)
(function) # ↑

Predicate to verify the signing_input by comparing a given mac to the mac for a newly signed message; comparison done in a constant-time manner to thwart timing attacks

Example

iex> mac = <<90, 34, 44, 252, 147, 130, 167, 173, 86, 191, 247, 93, 94, 12, 200, 30, 173, 115, 248, 89, 246, 222, 4, 213, 119, 74, 70, 20, 231, 194, 104, 103>>
...> shared_key = "gZH75aKtMN3Yj0iPS4hcgUuTwjAzZr9C"
...> JsonWebToken.Algorithm.Hmac.verify?(mac, :sha256, shared_key, "signing_input")
true