hash.go

/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

		 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package primitives

import (
	"crypto/hmac"
	"hash"
)

var (
	defaultHash          func() hash.Hash
	defaultHashAlgorithm string
)

// GetDefaultHash returns the default hash function used by the crypto layer
func GetDefaultHash() func() hash.Hash {
	return defaultHash
}

// GetHashAlgorithm return the default hash algorithm
func GetHashAlgorithm() string {
	return defaultHashAlgorithm
}

// NewHash returns a new hash function
func NewHash() hash.Hash {
	return GetDefaultHash()()
}

// Hash hashes the msh using the predefined hash function
func Hash(msg []byte) []byte {
	hash := NewHash()
	hash.Write(msg)
	return hash.Sum(nil)
}

// HMAC hmacs x using key key
func HMAC(key, x []byte) []byte {
	mac := hmac.New(GetDefaultHash(), key)
	mac.Write(x)

	return mac.Sum(nil)
}

// HMACTruncated hmacs x using key key and truncate to truncation
func HMACTruncated(key, x []byte, truncation int) []byte {
	mac := hmac.New(GetDefaultHash(), key)
	mac.Write(x)

	return mac.Sum(nil)[:truncation]
}

// HMACAESTruncated hmacs x using key key and truncate to AESKeyLength
func HMACAESTruncated(key, x []byte) []byte {
	return HMACTruncated(key, x, AESKeyLength)
}