The best replacement for cryptography is encryption.

The best alternatives to cryptography are rated as following:
★★★★★  encryption
★★★★  steganography
★★★★  cryptology
★★★  cryptanalysis
★  asymmetric cryptography
★  secret key cryptography
★  private key cryptography
  quantum cryptography
  public key cryptography
  secret-key cryptography

Your alternative for cryptography is not listed? Suggest!
Speaking about cryptography, one probably shouldn't forget about steganography.

Other search terms related to cryptography and their ratings are:

★★★★★ steganography
★★★ biometrics
You have in mind a companion for cryptography and it is not yet here? Propose!

Google Trends

Scale is based on the average worldwide traffic of cryptography in all years. Click on graph for more.