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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package packet
import (
"crypto"
"crypto/rand"
"io"
"time"
)
// Config collects a number of parameters along with sensible defaults.
// A nil *Config is valid and results in all default values.
type Config struct {
// Rand provides the source of entropy.
// If nil, the crypto/rand Reader is used.
Rand io.Reader
// DefaultHash is the default hash function to be used.
// If zero, SHA-256 is used.
DefaultHash crypto.Hash
// DefaultCipher is the cipher to be used.
// If zero, AES-128 is used.
DefaultCipher CipherFunction
// Time returns the current time as the number of seconds since the
// epoch. If Time is nil, time.Now is used.
Time func() time.Time
// DefaultCompressionAlgo is the compression algorithm to be
// applied to the plaintext before encryption. If zero, no
// compression is done.
DefaultCompressionAlgo CompressionAlgo
// CompressionConfig configures the compression settings.
CompressionConfig *CompressionConfig
// S2KCount is only used for symmetric encryption. It
// determines the strength of the passphrase stretching when
// the said passphrase is hashed to produce a key. S2KCount
// should be between 1024 and 65011712, inclusive. If Config
// is nil or S2KCount is 0, the value 65536 used. Not all
// values in the above range can be represented. S2KCount will
// be rounded up to the next representable value if it cannot
// be encoded exactly. When set, it is strongly encrouraged to
// use a value that is at least 65536. See RFC 4880 Section
// 3.7.1.3.
S2KCount int
// RSABits is the number of bits in new RSA keys made with NewEntity.
// If zero, then 2048 bit keys are created.
RSABits int
}
func (c *Config) Random() io.Reader {
if c == nil || c.Rand == nil {
return rand.Reader
}
return c.Rand
}
func (c *Config) Hash() crypto.Hash {
if c == nil || uint(c.DefaultHash) == 0 {
return crypto.SHA256
}
return c.DefaultHash
}
func (c *Config) Cipher() CipherFunction {
if c == nil || uint8(c.DefaultCipher) == 0 {
return CipherAES128
}
return c.DefaultCipher
}
func (c *Config) Now() time.Time {
if c == nil || c.Time == nil {
return time.Now()
}
return c.Time()
}
func (c *Config) Compression() CompressionAlgo {
if c == nil {
return CompressionNone
}
return c.DefaultCompressionAlgo
}
func (c *Config) PasswordHashIterations() int {
if c == nil || c.S2KCount == 0 {
return 0
}
return c.S2KCount
}