Package com.amazonaws.encryptionsdk.internal

Class HmacKeyDerivationFunction

java.lang.Object
com.amazonaws.encryptionsdk.internal.HmacKeyDerivationFunction
public final class HmacKeyDerivationFunction extends Object
HMAC-based Key Derivation Function. Adapted from Hkdf.java in aws-dynamodb-encryption-java
See Also:
RFC 5869

  • Method Details

    • getInstance

      public static HmacKeyDerivationFunction getInstance​(String algorithm) throws NoSuchAlgorithmException
      Returns an HmacKeyDerivationFunction object using the specified algorithm.
      Parameters:
      algorithm - the standard name of the requested MAC algorithm. See the Mac section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.
      Returns:
      the new Hkdf object
      Throws:
      NoSuchAlgorithmException - if no Provider supports a MacSpi implementation for the specified algorithm.

    • init

      public void init​(byte[] ikm)
      Initializes this Hkdf with input keying material. A default salt of HashLen zeros will be used (where HashLen is the length of the return value of the supplied algorithm).
      Parameters:
      ikm - the Input Keying Material

    • init

      public void init​(byte[] ikm, byte[] salt)
      Initializes this Hkdf with input keying material and a salt. If salt is null or of length 0, then a default salt of HashLen zeros will be used (where HashLen is the length of the return value of the supplied algorithm).
      Parameters:
      salt - the salt used for key extraction (optional)
      ikm - the Input Keying Material

    • deriveKey

      public byte[] deriveKey​(byte[] info, int length) throws IllegalStateException
      Returns a pseudorandom key of length bytes.
      Parameters:
      info - optional context and application specific information (can be a zero-length array).
      length - the length of the output key in bytes
      Returns:
      a pseudorandom key of length bytes.
      Throws:
      IllegalStateException - if this object has not been initialized