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authorJakob Unterwurzacher2021-08-21 10:55:20 +0200
committerJakob Unterwurzacher2021-08-21 10:55:20 +0200
commit2da0e13b1da4c903023200d6271b90f49077e8de (patch)
treeae7bb0e442e1e1ad450d4c376754a6ac5d41b10f
parentf6be765ef6d82c1b17b5159f9eebea2d03d18e1a (diff)
cryptocore: drop IVLen helper var
The IVLen var seems be a net loss in clarity. Drop it. Also add comments and normalize error messages.
-rw-r--r--internal/cryptocore/cryptocore.go28
1 files changed, 16 insertions, 12 deletions
diff --git a/internal/cryptocore/cryptocore.go b/internal/cryptocore/cryptocore.go
index 9f5b9bd..5729952 100644
--- a/internal/cryptocore/cryptocore.go
+++ b/internal/cryptocore/cryptocore.go
@@ -59,7 +59,8 @@ type CryptoCore struct {
AEADBackend AEADTypeEnum
// GCM needs unique IVs (nonces)
IVGenerator *nonceGenerator
- IVLen int
+ // IVLen in bytes
+ IVLen int
}
// New returns a new CryptoCore object or panics.
@@ -75,10 +76,11 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
len(key), aeadType, IVBitLen, useHKDF, forceDecode)
if len(key) != KeyLen {
- log.Panic(fmt.Sprintf("Unsupported key length %d", len(key)))
+ log.Panicf("Unsupported key length of %d bytes", len(key))
+ }
+ if IVBitLen != 96 && IVBitLen != 128 {
+ log.Panicf("Unsupported IV length of %d bits", IVBitLen)
}
- // We want the IV size in bytes
- IVLen := IVBitLen / 8
// Initialize EME for filename encryption.
var emeCipher *eme.EMECipher
@@ -107,12 +109,14 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if useHKDF {
gcmKey = hkdfDerive(key, hkdfInfoGCMContent, KeyLen)
} else {
+ // Filesystems created by gocryptfs v0.7 through v1.2 don't use HKDF.
+ // Example: tests/example_filesystems/v0.9
gcmKey = append([]byte{}, key...)
}
switch aeadType {
case BackendOpenSSL:
- if IVLen != 16 {
- log.Panic("stupidgcm only supports 128-bit IVs")
+ if IVBitLen != 128 {
+ log.Panicf("stupidgcm only supports 128-bit IVs, you wanted %d", IVBitLen)
}
aeadCipher = stupidgcm.New(gcmKey, forceDecode)
case BackendGoGCM:
@@ -120,7 +124,7 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
if err != nil {
log.Panic(err)
}
- aeadCipher, err = cipher.NewGCMWithNonceSize(goGcmBlockCipher, IVLen)
+ aeadCipher, err = cipher.NewGCMWithNonceSize(goGcmBlockCipher, IVBitLen/8)
if err != nil {
log.Panic(err)
}
@@ -129,9 +133,9 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
gcmKey[i] = 0
}
} else if aeadType == BackendAESSIV {
- if IVLen != 16 {
- // SIV supports any nonce size, but we only use 16.
- log.Panic("AES-SIV must use 16-byte nonces")
+ if IVBitLen != 128 {
+ // SIV supports any nonce size, but we only use 128.
+ log.Panicf("AES-SIV must use 128-bit IVs, you wanted %d", IVBitLen)
}
// AES-SIV uses 1/2 of the key for authentication, 1/2 for
// encryption, so we need a 64-bytes key for AES-256. Derive it from
@@ -156,8 +160,8 @@ func New(key []byte, aeadType AEADTypeEnum, IVBitLen int, useHKDF bool, forceDec
EMECipher: emeCipher,
AEADCipher: aeadCipher,
AEADBackend: aeadType,
- IVGenerator: &nonceGenerator{nonceLen: IVLen},
- IVLen: IVLen,
+ IVGenerator: &nonceGenerator{nonceLen: IVBitLen / 8},
+ IVLen: IVBitLen / 8,
}
}