63 lines
1.2 KiB
Go
63 lines
1.2 KiB
Go
// Package cryptocore wraps OpenSSL and Go GCM crypto and provides
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// a nonce generator.
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package cryptocore
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import (
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"crypto/aes"
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"crypto/cipher"
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"fmt"
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"github.com/rfjakob/gocryptfs/internal/stupidgcm"
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)
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const (
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KeyLen = 32 // AES-256
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AuthTagLen = 16
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)
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type CryptoCore struct {
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BlockCipher cipher.Block
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Gcm cipher.AEAD
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GcmIVGen *nonceGenerator
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IVLen int
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}
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// "New" returns a new CryptoCore object or panics.
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func New(key []byte, useOpenssl bool, GCMIV128 bool) *CryptoCore {
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if len(key) != KeyLen {
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panic(fmt.Sprintf("Unsupported key length %d", len(key)))
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}
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// We want the IV size in bytes
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IVLen := 96 / 8
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if GCMIV128 {
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IVLen = 128 / 8
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}
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// We always use built-in Go crypto for blockCipher because it is not
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// performance-critical.
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blockCipher, err := aes.NewCipher(key)
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if err != nil {
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panic(err)
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}
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var gcm cipher.AEAD
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if useOpenssl && GCMIV128 {
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// stupidgcm only supports 128-bit IVs
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gcm = stupidgcm.New(key)
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} else {
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gcm, err = goGCMWrapper(blockCipher, IVLen)
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if err != nil {
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panic(err)
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}
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}
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return &CryptoCore{
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BlockCipher: blockCipher,
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Gcm: gcm,
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GcmIVGen: &nonceGenerator{nonceLen: IVLen},
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IVLen: IVLen,
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}
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}
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