vendor/golang.org/x/crypto/openpgp/packet/config.go

   1 // Copyright 2012 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package packet
   6
   7 import (
   8         "crypto"
   9         "crypto/rand"
  10         "io"
  11         "time"
  12 )
  13
  14 // Config collects a number of parameters along with sensible defaults.
  15 // A nil *Config is valid and results in all default values.
  16 type Config struct {
  17         // Rand provides the source of entropy.
  18         // If nil, the crypto/rand Reader is used.
  19         Rand io.Reader
  20         // DefaultHash is the default hash function to be used.
  21         // If zero, SHA-256 is used.
  22         DefaultHash crypto.Hash
  23         // DefaultCipher is the cipher to be used.
  24         // If zero, AES-128 is used.
  25         DefaultCipher CipherFunction
  26         // Time returns the current time as the number of seconds since the
  27         // epoch. If Time is nil, time.Now is used.
  28         Time func() time.Time
  29         // DefaultCompressionAlgo is the compression algorithm to be
  30         // applied to the plaintext before encryption. If zero, no
  31         // compression is done.
  32         DefaultCompressionAlgo CompressionAlgo
  33         // CompressionConfig configures the compression settings.
  34         CompressionConfig *CompressionConfig
  35         // S2KCount is only used for symmetric encryption. It
  36         // determines the strength of the passphrase stretching when
  37         // the said passphrase is hashed to produce a key. S2KCount
  38         // should be between 1024 and 65011712, inclusive. If Config
  39         // is nil or S2KCount is 0, the value 65536 used. Not all
  40         // values in the above range can be represented. S2KCount will
  41         // be rounded up to the next representable value if it cannot
  42         // be encoded exactly. When set, it is strongly encrouraged to
  43         // use a value that is at least 65536. See RFC 4880 Section
  44         // 3.7.1.3.
  45         S2KCount int
  46         // RSABits is the number of bits in new RSA keys made with NewEntity.
  47         // If zero, then 2048 bit keys are created.
  48         RSABits int
  49 }
  50
  51 func (c *Config) Random() io.Reader {
  52         if c == nil || c.Rand == nil {
  53                 return rand.Reader
  54         }
  55         return c.Rand
  56 }
  57
  58 func (c *Config) Hash() crypto.Hash {
  59         if c == nil || uint(c.DefaultHash) == 0 {
  60                 return crypto.SHA256
  61         }
  62         return c.DefaultHash
  63 }
  64
  65 func (c *Config) Cipher() CipherFunction {
  66         if c == nil || uint8(c.DefaultCipher) == 0 {
  67                 return CipherAES128
  68         }
  69         return c.DefaultCipher
  70 }
  71
  72 func (c *Config) Now() time.Time {
  73         if c == nil || c.Time == nil {
  74                 return time.Now()
  75         }
  76         return c.Time()
  77 }
  78
  79 func (c *Config) Compression() CompressionAlgo {
  80         if c == nil {
  81                 return CompressionNone
  82         }
  83         return c.DefaultCompressionAlgo
  84 }
  85
  86 func (c *Config) PasswordHashIterations() int {
  87         if c == nil || c.S2KCount == 0 {
  88                 return 0
  89         }
  90         return c.S2KCount
  91 }