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crypto: Fix buffer extension in Decrypt()

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This commit is contained in:
Alexander Neumann 2015-05-05 00:07:57 +02:00
parent 589dbaaed2
commit 1f33e29ce2
2 changed files with 7 additions and 7 deletions
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10
crypto/crypto.go
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@ -276,11 +276,6 @@ func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error
panic("trying to decrypt invalid data: ciphertext too small") panic("trying to decrypt invalid data: ciphertext too small")
} }
if cap(plaintext) < len(ciphertextWithMac) {
// extend plaintext
plaintext = append(plaintext, make([]byte, len(ciphertextWithMac)-cap(plaintext))...)
}
// extract mac // extract mac
l := len(ciphertextWithMac) - macSize l := len(ciphertextWithMac) - macSize
ciphertextWithIV, mac := ciphertextWithMac[:l], ciphertextWithMac[l:] ciphertextWithIV, mac := ciphertextWithMac[:l], ciphertextWithMac[l:]
@ -293,6 +288,11 @@ func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error
// extract iv // extract iv
iv, ciphertext := ciphertextWithIV[:ivSize], ciphertextWithIV[ivSize:] iv, ciphertext := ciphertextWithIV[:ivSize], ciphertextWithIV[ivSize:]
if cap(plaintext) < len(ciphertext) {
// extend plaintext
plaintext = append(plaintext, make([]byte, len(ciphertext)-cap(plaintext))...)
}
// decrypt data // decrypt data
c, err := aes.NewCipher(ks.Encrypt[:]) c, err := aes.NewCipher(ks.Encrypt[:])
if err != nil { if err != nil {

4
crypto/crypto_test.go
View file

@ -107,10 +107,10 @@ func TestCornerCases(t *testing.T) {
"wrong length returned for ciphertext, expected 0, got %d", "wrong length returned for ciphertext, expected 0, got %d",
len(c)) len(c))
// this should decrypt to an empty slice // this should decrypt to nil
p, err := crypto.Decrypt(k, nil, c) p, err := crypto.Decrypt(k, nil, c)
OK(t, err) OK(t, err)
Equals(t, []byte{}, p) Equals(t, []byte(nil), p)
// test encryption for same slice, this should return an error // test encryption for same slice, this should return an error
_, err = crypto.Encrypt(k, c, c) _, err = crypto.Encrypt(k, c, c)