// 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 } 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 }