github.com/grailbio/base@v0.0.11/crypto/encryption/iv.go (about)

     1  // Copyright 2017 GRAIL, Inc. All rights reserved.
     2  // Use of this source code is governed by the Apache-2.0
     3  // license that can be found in the LICENSE file.
     4  
     5  package encryption
     6  
     7  import (
     8  	"encoding/hex"
     9  	"fmt"
    10  	"io"
    11  )
    12  
    13  // IV represents the initialization vector used to encrypt a block.
    14  type IV []byte
    15  
    16  // MarshalJSON marshals an IV as a hex encoded string.
    17  func (iv IV) MarshalJSON() ([]byte, error) {
    18  	if len(iv) == 0 {
    19  		return []byte(`""`), nil
    20  	}
    21  	dst := make([]byte, hex.EncodedLen(len(iv))+2)
    22  	hex.Encode(dst[1:], iv)
    23  	// need to supply leading/trailing double quotes.
    24  	dst[0], dst[len(dst)-1] = '"', '"'
    25  	return dst, nil
    26  }
    27  
    28  // UnmarshalJSON unmarshals a hex encoded string into an IV.
    29  func (iv *IV) UnmarshalJSON(data []byte) error {
    30  	// need to strip leading and trailing double quotes
    31  	if data[0] != '"' || data[len(data)-1] != '"' {
    32  		return fmt.Errorf("IV is not quoted")
    33  	}
    34  	data = data[1 : len(data)-1]
    35  	*iv = make([]byte, hex.DecodedLen(len(data)))
    36  	_, err := hex.Decode(*iv, data)
    37  	return err
    38  }
    39  
    40  // SetRandSource sets the source of random numbers be used and is intended for
    41  // primarily for testing purposes.
    42  func SetRandSource(rd io.Reader) {
    43  	randomSource = rd
    44  }