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ecdh-es

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Elliptic Curve Diffie-Hellman with ephemeral-static keys implementation for NodeJS

35 lines (25 loc) • 1.1 kB
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BigInt = require 'bigi' { createHash, createHmac } = require 'crypto' { randomBuffer } = require 'secure-random' # Buffer reader, consumes bytes as they're being read reader = (buff, pos=0) -> (len) -> if len? then buff[pos...(pos+=len)] else buff[pos..] # SHA256 convenience wrapper sha256 = (d) -> createHash('sha256').update(d).digest() # SHA512 convenience wrapper sha512 = (d) -> createHash('sha512').update(d).digest() # SHA256 HMAC convenience wrapper hmac = (key, data...) -> h = createHmac 'sha256', key h.update d for d in data h.digest() # Create 32 random bytes based on CSPRNG and user-provided entropy rand = (entropy...) -> hmac randomBuffer(32), entropy... # Create random private key rand_key = (curve, entropy...) -> BigInt.fromBuffer(rand entropy...).mod(curve.n) # Get the matching public key of a private key get_pub = (curve, privkey) -> curve.G.multiply(privkey).getEncoded(true) # Checks if two buffers are equal buff_eq = (a, b) -> a.toString('hex') is b.toString('hex') module.exports = { reader, sha256, sha512, hmac, rand, rand_key, get_pub, buff_eq }