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authorJakob Unterwurzacher2021-09-04 11:41:56 +0200
committerJakob Unterwurzacher2021-09-07 18:14:05 +0200
commite2ec048a09889b2bf71e8bbfef9f0584ff7d69db (patch)
tree84bb1f8c709f8db3b2dd551c7c5343c0ffe44ed9 /internal
parentbf572aef88963732849b8e5ae679e63c6be4aa46 (diff)
stupidgcm: introduce stupidAEADCommon and use for both chacha & gcm
Nice deduplication and brings the GCM decrypt speed up to par. internal/speed$ benchstat old new name old time/op new time/op delta StupidGCM-4 4.71µs ± 0% 4.66µs ± 0% -0.99% (p=0.008 n=5+5) StupidGCMDecrypt-4 5.77µs ± 1% 4.51µs ± 0% -21.80% (p=0.008 n=5+5) name old speed new speed delta StupidGCM-4 870MB/s ± 0% 879MB/s ± 0% +1.01% (p=0.008 n=5+5) StupidGCMDecrypt-4 710MB/s ± 1% 908MB/s ± 0% +27.87% (p=0.008 n=5+5)
Diffstat (limited to 'internal')
-rw-r--r--internal/stupidgcm/chacha.go35
-rw-r--r--internal/stupidgcm/chacha_test.go (renamed from internal/stupidgcm/stupidchacha_test.go)0
-rw-r--r--internal/stupidgcm/common.go68
-rw-r--r--internal/stupidgcm/common_test.go17
-rw-r--r--internal/stupidgcm/gcm.go45
-rw-r--r--internal/stupidgcm/gcm_test.go (renamed from internal/stupidgcm/stupidgcm_test.go)0
-rw-r--r--internal/stupidgcm/openssl.go108
-rw-r--r--internal/stupidgcm/openssl_aead.c (renamed from internal/stupidgcm/chacha.c)26
-rw-r--r--internal/stupidgcm/openssl_aead.h (renamed from internal/stupidgcm/chacha.h)13
-rw-r--r--internal/stupidgcm/stupidchacha.go156
-rw-r--r--internal/stupidgcm/stupidgcm.go204
-rw-r--r--internal/stupidgcm/xchacha.go (renamed from internal/stupidgcm/stupidxchacha.go)10
-rw-r--r--internal/stupidgcm/xchacha_test.go (renamed from internal/stupidgcm/stupidxchacha_test.go)0
13 files changed, 280 insertions, 402 deletions
diff --git a/internal/stupidgcm/chacha.go b/internal/stupidgcm/chacha.go
new file mode 100644
index 0000000..37f7e1f
--- /dev/null
+++ b/internal/stupidgcm/chacha.go
@@ -0,0 +1,35 @@
+// +build !without_openssl
+
+package stupidgcm
+
+import (
+ "crypto/cipher"
+ "log"
+
+ "golang.org/x/crypto/chacha20poly1305"
+)
+
+/*
+#include <openssl/evp.h>
+*/
+import "C"
+
+type stupidChacha20poly1305 struct {
+ stupidAEADCommon
+}
+
+// Verify that we satisfy the cipher.AEAD interface
+var _ cipher.AEAD = &stupidChacha20poly1305{}
+
+func newChacha20poly1305(key []byte) *stupidChacha20poly1305 {
+ if len(key) != chacha20poly1305.KeySize {
+ log.Panicf("Only %d-byte keys are supported, you passed %d bytes", chacha20poly1305.KeySize, len(key))
+ }
+ return &stupidChacha20poly1305{
+ stupidAEADCommon{
+ key: append([]byte{}, key...), // private copy
+ openSSLEVPCipher: C.EVP_chacha20_poly1305(),
+ nonceSize: chacha20poly1305.NonceSize,
+ },
+ }
+}
diff --git a/internal/stupidgcm/stupidchacha_test.go b/internal/stupidgcm/chacha_test.go
index 513b68f..513b68f 100644
--- a/internal/stupidgcm/stupidchacha_test.go
+++ b/internal/stupidgcm/chacha_test.go
diff --git a/internal/stupidgcm/common.go b/internal/stupidgcm/common.go
new file mode 100644
index 0000000..3788315
--- /dev/null
+++ b/internal/stupidgcm/common.go
@@ -0,0 +1,68 @@
+package stupidgcm
+
+import (
+ "log"
+)
+
+/*
+#include <openssl/evp.h>
+*/
+import "C"
+
+type stupidAEADCommon struct {
+ wiped bool
+ key []byte
+ openSSLEVPCipher *C.EVP_CIPHER
+ nonceSize int
+}
+
+// Overhead returns the number of bytes that are added for authentication.
+//
+// Part of the cipher.AEAD interface.
+func (c *stupidAEADCommon) Overhead() int {
+ return tagLen
+}
+
+// NonceSize returns the required size of the nonce / IV
+//
+// Part of the cipher.AEAD interface.
+func (c *stupidAEADCommon) NonceSize() int {
+ return c.nonceSize
+}
+
+// Seal encrypts "in" using "iv" and "authData" and append the result to "dst"
+//
+// Part of the cipher.AEAD interface.
+func (c *stupidAEADCommon) Seal(dst, iv, in, authData []byte) []byte {
+ return openSSLSeal(c, dst, iv, in, authData)
+}
+
+// Open decrypts "in" using "iv" and "authData" and append the result to "dst"
+//
+// Part of the cipher.AEAD interface.
+func (c *stupidAEADCommon) Open(dst, iv, in, authData []byte) ([]byte, error) {
+ return openSSLOpen(c, dst, iv, in, authData)
+}
+
+// Wipe tries to wipe the key from memory by overwriting it with zeros.
+//
+// This is not bulletproof due to possible GC copies, but
+// still raises the bar for extracting the key.
+func (c *stupidAEADCommon) Wipe() {
+ key := c.key
+ c.wiped = true
+ c.key = nil
+ for i := range key {
+ key[i] = 0
+ }
+}
+
+func (c *stupidAEADCommon) Wiped() bool {
+ if c.wiped {
+ return true
+ }
+ if len(c.key) != keyLen {
+ log.Panicf("wrong key length %d", len(c.key))
+ }
+ return false
+}
diff --git a/internal/stupidgcm/common_test.go b/internal/stupidgcm/common_test.go
index 8123ce2..a8080ca 100644
--- a/internal/stupidgcm/common_test.go
+++ b/internal/stupidgcm/common_test.go
@@ -162,25 +162,26 @@ func testCorruption(t *testing.T, c cipher.AEAD) {
}
}
-type Wiper interface {
- Wipe()
-}
-
func testWipe(t *testing.T, c cipher.AEAD) {
switch c2 := c.(type) {
case *StupidGCM:
c2.Wipe()
- if c2.key != nil {
- t.Fatal("key is not nil")
+ if !c2.Wiped() {
+ t.Error("c2.wiped is not set")
+ }
+ for _, v := range c2.key {
+ if v != 0 {
+ t.Fatal("c2._key is not zeroed")
+ }
}
case *stupidChacha20poly1305:
c2.Wipe()
- if !c2.wiped {
+ if !c2.Wiped() {
t.Error("c2.wiped is not set")
}
for _, v := range c2.key {
if v != 0 {
- t.Fatal("c2.key is not zeroed")
+ t.Fatal("c2._key is not zeroed")
}
}
case *stupidXchacha20poly1305:
diff --git a/internal/stupidgcm/gcm.go b/internal/stupidgcm/gcm.go
new file mode 100644
index 0000000..439e7a7
--- /dev/null
+++ b/internal/stupidgcm/gcm.go
@@ -0,0 +1,45 @@
+// +build !without_openssl
+
+// Package stupidgcm is a thin wrapper for OpenSSL's GCM encryption and
+// decryption functions. It only support 32-byte keys and 16-bit IVs.
+package stupidgcm
+
+// #include <openssl/evp.h>
+import "C"
+
+import (
+ "crypto/cipher"
+ "log"
+)
+
+const (
+ // BuiltWithoutOpenssl indicates if openssl been disabled at compile-time
+ BuiltWithoutOpenssl = false
+
+ keyLen = 32
+ ivLen = 16
+ tagLen = 16
+)
+
+// StupidGCM implements the cipher.AEAD interface
+type StupidGCM struct {
+ stupidAEADCommon
+}
+
+// Verify that we satisfy the interface
+var _ cipher.AEAD = &StupidGCM{}
+
+// New returns a new cipher.AEAD implementation..
+func New(keyIn []byte, forceDecode bool) cipher.AEAD {
+ if len(keyIn) != keyLen {
+ log.Panicf("Only %d-byte keys are supported", keyLen)
+ }
+ return &StupidGCM{
+ stupidAEADCommon{
+ // Create a private copy of the key
+ key: append([]byte{}, keyIn...),
+ openSSLEVPCipher: C.EVP_aes_256_gcm(),
+ nonceSize: ivLen,
+ },
+ }
+}
diff --git a/internal/stupidgcm/stupidgcm_test.go b/internal/stupidgcm/gcm_test.go
index 5323afa..5323afa 100644
--- a/internal/stupidgcm/stupidgcm_test.go
+++ b/internal/stupidgcm/gcm_test.go
diff --git a/internal/stupidgcm/openssl.go b/internal/stupidgcm/openssl.go
new file mode 100644
index 0000000..d57d100
--- /dev/null
+++ b/internal/stupidgcm/openssl.go
@@ -0,0 +1,108 @@
+package stupidgcm
+
+import (
+ "fmt"
+ "log"
+)
+
+/*
+#include "openssl_aead.h"
+#cgo pkg-config: libcrypto
+*/
+import "C"
+
+func openSSLSeal(a *stupidAEADCommon, dst, iv, in, authData []byte) []byte {
+ if a.Wiped() {
+ panic("BUG: tried to use wiped key")
+ }
+ if len(iv) != a.NonceSize() {
+ log.Panicf("Only %d-byte IVs are supported, you passed %d bytes", a.NonceSize(), len(iv))
+ }
+ if len(in) == 0 {
+ log.Panic("Zero-length input data is not supported")
+ }
+
+ // If the "dst" slice is large enough we can use it as our output buffer
+ outLen := len(in) + tagLen
+ var buf []byte
+ inplace := false
+ if cap(dst)-len(dst) >= outLen {
+ inplace = true
+ buf = dst[len(dst) : len(dst)+outLen]
+ } else {
+ buf = make([]byte, outLen)
+ }
+
+ res := int(C.openssl_aead_seal(a.openSSLEVPCipher,
+ (*C.uchar)(&in[0]),
+ C.int(len(in)),
+ (*C.uchar)(&authData[0]),
+ C.int(len(authData)),
+ (*C.uchar)(&a.key[0]),
+ C.int(len(a.key)),
+ (*C.uchar)(&iv[0]),
+ C.int(len(iv)),
+ (*C.uchar)(&buf[0]),
+ C.int(len(buf))))
+
+ if res != outLen {
+ log.Panicf("expected length %d, got %d", outLen, res)
+ }
+
+ if inplace {
+ return dst[:len(dst)+outLen]
+ }
+ return append(dst, buf...)
+}
+
+func openSSLOpen(a *stupidAEADCommon, dst, iv, in, authData []byte) ([]byte, error) {
+ if a.Wiped() {
+ panic("BUG: tried to use wiped key")
+ }
+ if len(iv) != a.NonceSize() {
+ log.Panicf("Only %d-byte IVs are supported, you passed %d bytes", a.NonceSize(), len(iv))
+ }
+ if len(in) <= tagLen {
+ return nil, fmt.Errorf("stupidChacha20poly1305: input data too short (%d bytes)", len(in))
+ }
+
+ // If the "dst" slice is large enough we can use it as our output buffer
+ outLen := len(in) - tagLen
+ var buf []byte
+ inplace := false
+ if cap(dst)-len(dst) >= outLen {
+ inplace = true
+ buf = dst[len(dst) : len(dst)+outLen]
+ } else {
+ buf = make([]byte, len(in)-tagLen)
+ }
+
+ ciphertext := in[:len(in)-tagLen]
+ tag := in[len(in)-tagLen:]
+
+ res := int(C.openssl_aead_open(a.openSSLEVPCipher,
+ (*C.uchar)(&ciphertext[0]),
+ C.int(len(ciphertext)),
+ (*C.uchar)(&authData[0]),
+ C.int(len(authData)),
+ (*C.uchar)(&tag[0]),
+ C.int(len(tag)),
+ (*C.uchar)(&a.key[0]),
+ C.int(len(a.key)),
+ (*C.uchar)(&iv[0]),
+ C.int(len(iv)),
+ (*C.uchar)(&buf[0]),
+ C.int(len(buf))))
+
+ if res < 0 {
+ return nil, ErrAuth
+ }
+ if res != outLen {
+ log.Panicf("unexpected length %d", res)
+ }
+
+ if inplace {
+ return dst[:len(dst)+outLen], nil
+ }
+ return append(dst, buf...), nil
+}
diff --git a/internal/stupidgcm/chacha.c b/internal/stupidgcm/openssl_aead.c
index 05d68af..9dc6866 100644
--- a/internal/stupidgcm/chacha.c
+++ b/internal/stupidgcm/openssl_aead.c
@@ -1,4 +1,4 @@
-#include "chacha.h"
+#include "openssl_aead.h"
#include <openssl/evp.h>
#include <stdio.h>
//#cgo pkg-config: libcrypto
@@ -9,24 +9,12 @@ static void panic(const char* const msg)
__builtin_trap();
}
-static const EVP_CIPHER* getEvpCipher(enum aeadType cipherId)
-{
- switch (cipherId) {
- case aeadTypeChacha:
- return EVP_chacha20_poly1305();
- case aeadTypeGcm:
- return EVP_aes_256_gcm();
- }
- panic("unknown cipherId");
- return NULL;
-}
-
// We only support 16-byte tags
static const int supportedTagLen = 16;
// https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
-int aead_seal(
- const enum aeadType cipherId,
+int openssl_aead_seal(
+ const EVP_CIPHER* evpCipher,
const unsigned char* const plaintext,
const int plaintextLen,
const unsigned char* const authData,
@@ -38,8 +26,6 @@ int aead_seal(
unsigned char* const ciphertext,
const int ciphertextBufLen)
{
- const EVP_CIPHER* evpCipher = getEvpCipher(cipherId);
-
// Create scratch space "ctx"
EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
if (!ctx) {
@@ -111,8 +97,8 @@ int aead_seal(
return ciphertextLen;
}
-int aead_open(
- const enum aeadType cipherId,
+int openssl_aead_open(
+ const EVP_CIPHER* evpCipher,
const unsigned char* const ciphertext,
const int ciphertextLen,
const unsigned char* const authData,
@@ -126,8 +112,6 @@ int aead_open(
unsigned char* const plaintext,
const int plaintextBufLen)
{
- const EVP_CIPHER* evpCipher = getEvpCipher(cipherId);
-
// Create scratch space "ctx"
EVP_CIPHER_CTX* ctx = EVP_CIPHER_CTX_new();
if (!ctx) {
diff --git a/internal/stupidgcm/chacha.h b/internal/stupidgcm/openssl_aead.h
index a5eac04..6a818b6 100644
--- a/internal/stupidgcm/chacha.h
+++ b/internal/stupidgcm/openssl_aead.h
@@ -1,10 +1,7 @@
-enum aeadType {
- aeadTypeChacha = 1,
- aeadTypeGcm = 2,
-};
+#include <openssl/evp.h>
-int aead_seal(
- const enum aeadType cipherId,
+int openssl_aead_seal(
+ const EVP_CIPHER* evpCipher,
const unsigned char* const plaintext,
const int plaintextLen,
const unsigned char* const authData,
@@ -16,8 +13,8 @@ int aead_seal(
unsigned char* const ciphertext,
const int ciphertextBufLen);
-int aead_open(
- const enum aeadType cipherId,
+int openssl_aead_open(
+ const EVP_CIPHER* evpCipher,
const unsigned char* const ciphertext,
const int ciphertextLen,
const unsigned char* const authData,
diff --git a/internal/stupidgcm/stupidchacha.go b/internal/stupidgcm/stupidchacha.go
deleted file mode 100644
index 5073aa3..0000000
--- a/internal/stupidgcm/stupidchacha.go
+++ /dev/null
@@ -1,156 +0,0 @@
-// +build !without_openssl
-
-package stupidgcm
-
-import (
- "crypto/cipher"
- "fmt"
- "log"
-
- "golang.org/x/crypto/chacha20poly1305"
-)
-
-/*
-#include <openssl/evp.h>
-#include "chacha.h"
-#cgo pkg-config: libcrypto
-*/
-import "C"
-
-type stupidChacha20poly1305 struct {
- key [chacha20poly1305.KeySize]byte
- wiped bool
-}
-
-// Verify that we satisfy the cipher.AEAD interface
-var _ cipher.AEAD = &stupidChacha20poly1305{}
-
-func newChacha20poly1305(key []byte) cipher.AEAD {
- if len(key) != chacha20poly1305.KeySize {
- log.Panicf("Only %d-byte keys are supported, you passed %d bytes", chacha20poly1305.KeySize, len(key))
- }
- ret := new(stupidChacha20poly1305)
- copy(ret.key[:], key)
- return ret
-}
-
-// NonceSize returns the required size of the nonce / IV.
-func (g *stupidChacha20poly1305) NonceSize() int {
- return chacha20poly1305.NonceSize
-}
-
-// Overhead returns the number of bytes that are added for authentication.
-func (g *stupidChacha20poly1305) Overhead() int {
- return tagLen
-}
-
-// Seal encrypts "in" using "iv" and "authData" and append the result to "dst"
-func (g *stupidChacha20poly1305) Seal(dst, iv, in, authData []byte) []byte {
- if g.wiped {
- panic("BUG: tried to use wiped key")
- }
- if len(iv) != g.NonceSize() {
- log.Panicf("Only %d-byte IVs are supported, you passed %d bytes", g.NonceSize(), len(iv))
- }
- if len(in) == 0 {
- log.Panic("Zero-length input data is not supported")
- }
- if len(g.key) != chacha20poly1305.KeySize {
- log.Panicf("Wrong key length: %d. Key has been wiped?", len(g.key))
- }
-
- // If the "dst" slice is large enough we can use it as our output buffer
- outLen := len(in) + tagLen
- var buf []byte
- inplace := false
- if cap(dst)-len(dst) >= outLen {
- inplace = true
- buf = dst[len(dst) : len(dst)+outLen]
- } else {
- buf = make([]byte, outLen)
- }
-
- C.aead_seal(C.aeadTypeChacha,
- (*C.uchar)(&in[0]),
- C.int(len(in)),
- (*C.uchar)(&authData[0]),
- C.int(len(authData)),
- (*C.uchar)(&g.key[0]),
- C.int(len(g.key)),
- (*C.uchar)(&iv[0]),
- C.int(len(iv)),
- (*C.uchar)(&buf[0]),
- C.int(len(buf)))
-
- if inplace {
- return dst[:len(dst)+outLen]
- }
- return append(dst, buf...)
-}
-
-// Open decrypts "in" using "iv" and "authData" and append the result to "dst"
-func (g *stupidChacha20poly1305) Open(dst, iv, in, authData []byte) ([]byte, error) {
- if g.wiped {
- panic("BUG: tried to use wiped key")
- }
- if len(iv) != g.NonceSize() {
- log.Panicf("Only %d-byte IVs are supported", g.NonceSize())
- }
- if len(g.key) != chacha20poly1305.KeySize {
- log.Panicf("Wrong key length: %d. Key has been wiped?", len(g.key))
- }
- if len(in) <= tagLen {
- return nil, fmt.Errorf("stupidChacha20poly1305: input data too short (%d bytes)", len(in))
- }
-
- // If the "dst" slice is large enough we can use it as our output buffer
- outLen := len(in) - tagLen
- var buf []byte
- inplace := false
- if cap(dst)-len(dst) >= outLen {
- inplace = true
- buf = dst[len(dst) : len(dst)+outLen]
- } else {
- buf = make([]byte, len(in)-tagLen)
- }
-
- ciphertext := in[:len(in)-tagLen]
- tag := in[len(in)-tagLen:]
-
- res := int(C.aead_open(C.aeadTypeChacha,
- (*C.uchar)(&ciphertext[0]),
- C.int(len(ciphertext)),
- (*C.uchar)(&authData[0]),
- C.int(len(authData)),
- (*C.uchar)(&tag[0]),
- C.int(len(tag)),
- (*C.uchar)(&g.key[0]),
- C.int(len(g.key)),
- (*C.uchar)(&iv[0]),
- C.int(len(iv)),
- (*C.uchar)(&buf[0]),
- C.int(len(buf))))
-
- if res < 0 {
- return nil, ErrAuth
- }
- if res != outLen {
- log.Panicf("unexpected length %d", res)
- }
-
- if inplace {
- return dst[:len(dst)+outLen], nil
- }
- return append(dst, buf...), nil
-}
-
-// Wipe tries to wipe the key from memory by overwriting it with zeros.
-//
-// This is not bulletproof due to possible GC copies, but
-// still raises the bar for extracting the key.
-func (g *stupidChacha20poly1305) Wipe() {
- g.wiped = true
- for i := range g.key {
- g.key[i] = 0
- }
-}
diff --git a/internal/stupidgcm/stupidgcm.go b/internal/stupidgcm/stupidgcm.go
deleted file mode 100644
index 46b6b86..0000000
--- a/internal/stupidgcm/stupidgcm.go
+++ /dev/null
@@ -1,204 +0,0 @@
-// +build !without_openssl
-
-// Package stupidgcm is a thin wrapper for OpenSSL's GCM encryption and
-// decryption functions. It only support 32-byte keys and 16-bit IVs.
-package stupidgcm
-
-// #include <openssl/evp.h>
-// #include "chacha.h"
-// #cgo pkg-config: libcrypto
-import "C"
-
-import (
- "crypto/cipher"
- "fmt"
- "log"
- "unsafe"
-)
-
-const (
- // BuiltWithoutOpenssl indicates if openssl been disabled at compile-time
- BuiltWithoutOpenssl = false
-
- keyLen = 32
- ivLen = 16
- tagLen = 16
-)
-
-// StupidGCM implements the cipher.AEAD interface
-type StupidGCM struct {
- key []byte
- forceDecode bool
-}
-
-// Verify that we satisfy the cipher.AEAD interface
-var _ cipher.AEAD = &StupidGCM{}
-
-// New returns a new cipher.AEAD implementation..
-func New(keyIn []byte, forceDecode bool) cipher.AEAD {
- if len(keyIn) != keyLen {
- log.Panicf("Only %d-byte keys are supported", keyLen)
- }
- // Create a private copy of the key
- key := append([]byte{}, keyIn...)
- return &StupidGCM{key: key, forceDecode: forceDecode}
-}
-
-// NonceSize returns the required size of the nonce / IV.
-func (g *StupidGCM) NonceSize() int {
- return ivLen
-}
-
-// Overhead returns the number of bytes that are added for authentication.
-func (g *StupidGCM) Overhead() int {
- return tagLen
-}
-
-// Seal encrypts "in" using "iv" and "authData" and append the result to "dst"
-func (g *StupidGCM) Seal(dst, iv, in, authData []byte) []byte {
- if len(iv) != ivLen {
- log.Panicf("Only %d-byte IVs are supported", ivLen)
- }
- if len(in) == 0 {
- log.Panic("Zero-length input data is not supported")
- }
- if len(g.key) != keyLen {
- log.Panicf("Wrong key length: %d. Key has been wiped?", len(g.key))
- }
-
- // If the "dst" slice is large enough we can use it as our output buffer
- outLen := len(in) + tagLen
- var buf []byte
- inplace := false
- if cap(dst)-len(dst) >= outLen {
- inplace = true
- buf = dst[len(dst) : len(dst)+outLen]
- } else {
- buf = make([]byte, outLen)
- }
-
- C.aead_seal(C.aeadTypeGcm,
- (*C.uchar)(&in[0]),
- C.int(len(in)),
- (*C.uchar)(&authData[0]),
- C.int(len(authData)),
- (*C.uchar)(&g.key[0]),
- C.int(len(g.key)),
- (*C.uchar)(&iv[0]),
- C.int(len(iv)),
- (*C.uchar)(&buf[0]),
- C.int(len(buf)))
-
- if inplace {
- return dst[:len(dst)+outLen]
- }
- return append(dst, buf...)
-}
-
-// Open decrypts "in" using "iv" and "authData" and append the result to "dst"
-func (g *StupidGCM) Open(dst, iv, in, authData []byte) ([]byte, error) {
- if len(iv) != ivLen {
- log.Panicf("Only %d-byte IVs are supported", ivLen)
- }
- if len(g.key) != keyLen {
- log.Panicf("Wrong key length: %d. Key has been wiped?", len(g.key))
- }
- if len(in) <= tagLen {
- return nil, fmt.Errorf("stupidgcm: input data too short (%d bytes)", len(in))
- }
-
- // If the "dst" slice is large enough we can use it as our output buffer
- outLen := len(in) - tagLen
- var buf []byte
- inplace := false
- if cap(dst)-len(dst) >= outLen {
- inplace = true
- buf = dst[len(dst) : len(dst)+outLen]
- } else {
- buf = make([]byte, len(in)-tagLen)
- }
-
- ciphertext := in[:len(in)-tagLen]
- tag := in[len(in)-tagLen:]
-
- // https://wiki.openssl.org/index.php/EVP_Authenticated_Encryption_and_Decryption#Authenticated_Encryption_using_GCM_mode
-
- // Create scratch space "context"
- ctx := C.EVP_CIPHER_CTX_new()
- if ctx == nil {
- log.Panic("EVP_CIPHER_CTX_new failed")
- }
-
- // Set cipher to AES-256
- if C.EVP_DecryptInit_ex(ctx, C.EVP_aes_256_gcm(), nil, nil, nil) != 1 {
- log.Panic("EVP_DecryptInit_ex I failed")
- }
-
- // Use 16-byte IV
- if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_GCM_SET_IVLEN, ivLen, nil) != 1 {
- log.Panic("EVP_CIPHER_CTX_ctrl EVP_CTRL_GCM_SET_IVLEN failed")
- }
-
- // Set key and IV
- if C.EVP_DecryptInit_ex(ctx, nil, nil, (*C.uchar)(&g.key[0]), (*C.uchar)(&iv[0])) != 1 {
- log.Panic("EVP_DecryptInit_ex II failed")
- }
-
- // Set expected GMAC tag
- if C.EVP_CIPHER_CTX_ctrl(ctx, C.EVP_CTRL_GCM_SET_TAG, tagLen, (unsafe.Pointer)(&tag[0])) != 1 {
- log.Panic("EVP_CIPHER_CTX_ctrl failed")
- }
-
- // Provide authentication data
- var resultLen C.int
- if C.EVP_DecryptUpdate(ctx, nil, &resultLen, (*C.uchar)(&authData[0]), C.int(len(authData))) != 1 {
- log.Panic("EVP_DecryptUpdate authData failed")
- }
- if int(resultLen) != len(authData) {
- log.Panicf("Unexpected length %d", resultLen)
- }
-
- // Decrypt "ciphertext" into "buf"
- if C.EVP_DecryptUpdate(ctx, (*C.uchar)(&buf[0]), &resultLen, (*C.uchar)(&ciphertext[0]), C.int(len(ciphertext))) != 1 {
- log.Panic("EVP_DecryptUpdate failed")
- }
- if int(resultLen) != len(ciphertext) {
- log.Panicf("Unexpected length %d", resultLen)
- }
-
- // Check GMAC
- dummy := make([]byte, 16)
- res := C.EVP_DecryptFinal_ex(ctx, (*C.uchar)(&dummy[0]), &resultLen)
- if resultLen != 0 {
- log.Panicf("Unexpected length %d", resultLen)
- }
-
- // Free scratch space
- C.EVP_CIPHER_CTX_free(ctx)
-
- if res != 1 {
- // The error code must always be checked by the calling function, because the decrypted buffer
- // may contain corrupted data that we are returning in case the user forced reads
- if g.forceDecode {
- return append(dst, buf...), ErrAuth
- }
- return nil, ErrAuth
- }
-
- if inplace {
- return dst[:len(dst)+outLen], nil
- }
- return append(dst, buf...), nil
-}
-
-// Wipe tries to wipe the AES key from memory by overwriting it with zeros
-// and setting the reference to nil.
-//
-// This is not bulletproof due to possible GC copies, but
-// still raises the bar for extracting the key.
-func (g *StupidGCM) Wipe() {
- for i := range g.key {
- g.key[i] = 0
- }
- g.key = nil
-}
diff --git a/internal/stupidgcm/stupidxchacha.go b/internal/stupidgcm/xchacha.go
index 9f2ac2f..d8668dc 100644
--- a/internal/stupidgcm/stupidxchacha.go
+++ b/internal/stupidgcm/xchacha.go
@@ -17,6 +17,8 @@ import (
)
type stupidXchacha20poly1305 struct {
+ // array instead of byte slice like
+ // `struct xchacha20poly1305` in x/crypto/chacha20poly1305
key [chacha20poly1305.KeySize]byte
wiped bool
}
@@ -41,7 +43,7 @@ func (*stupidXchacha20poly1305) NonceSize() int {
}
func (*stupidXchacha20poly1305) Overhead() int {
- return 16
+ return tagLen
}
func (x *stupidXchacha20poly1305) Seal(dst, nonce, plaintext, additionalData []byte) []byte {
@@ -61,9 +63,8 @@ func (x *stupidXchacha20poly1305) Seal(dst, nonce, plaintext, additionalData []b
panic("plaintext too large")
}
- c := new(stupidChacha20poly1305)
hKey, _ := chacha20.HChaCha20(x.key[:], nonce[0:16])
- copy(c.key[:], hKey)
+ c := newChacha20poly1305(hKey)
defer c.Wipe()
// The first 4 bytes of the final nonce are unused counter space.
@@ -87,9 +88,8 @@ func (x *stupidXchacha20poly1305) Open(dst, nonce, ciphertext, additionalData []
panic("ciphertext too large")
}
- c := new(stupidChacha20poly1305)
hKey, _ := chacha20.HChaCha20(x.key[:], nonce[0:16])
- copy(c.key[:], hKey)
+ c := newChacha20poly1305(hKey)
defer c.Wipe()
// The first 4 bytes of the final nonce are unused counter space.
diff --git a/internal/stupidgcm/stupidxchacha_test.go b/internal/stupidgcm/xchacha_test.go
index fdea8b5..fdea8b5 100644
--- a/internal/stupidgcm/stupidxchacha_test.go
+++ b/internal/stupidgcm/xchacha_test.go