TimeoutSignatureFormat

Timeout Signature Format v0.6b

All keyCzar timeout signatures are preceded with an OutputHeader (consisting of a VersionByte and KeyHash). Timeout signatures are generated by passing in an absolute timeout T in "epoch time", which is the number of milliseconds since January 1, 1970 00:00:00 GMT. The timeout will be given as an 8-byte big-endian long value representation. An input message M and timeout T will be concatenated and terminated with the VersionByte before being signed:

OutputHeader	T	Sign(T . M . VersionByte)

(Let "." be a byte-wise concatenation operator.)

HMAC-SHA1 Example

OutputHeader	T	Sign(T . M . VersionByte)
5 bytes	8 bytes	20 bytes

Timeout Signature Format v0.5b

Given an input message M and timeout T, both the OutputHeader, T, and M will be signed together:

OutputHeader	T	Sign(OutputHeader . T . M)

(Let "." be a byte-wise concatenation operator.)