Patent ID: 7813503

Claim:
A method for generating a key for a cryptographic engine, said method comprising: initializing in a deterministic random bit generator a seed value, V, as a first function of an entropy_input; generating by said deterministic random bit generator a temporary seed value, tempV, by applying said first function to said seed value, V; generating by said deterministic random bit generator a requested number of pseudorandom bits as a second function of said temporary value, tempV; setting by said deterministic random bit generator said value, V, equal to a third function of said temporary value, tempV; outputting by said deterministic random bit generator to said cryptographic engine said requested number of pseudorandom bits; and using, at said cryptographic engine, said requested number of pseudorandom bits as said key in a cryptographic operation, wherein said first and third functions are one-way functions which take a variable length input and generate an output of a predetermined length, and which maintain said variable length input's entropy; and said second function is a pseudorandom function which takes in input equal in length to said output of said first and third functions and generates said requested number of pseudorandom bits.