crypto: add CTR mode support

Introduce CTR mode support for the cipher APIs.
CTR mode uses a counter rather than a traditional IV.
The counter has additional properties, including a nonce
and initial counter block. We reuse the ctx->iv as
the counter for conveniences.

Both libgcrypt and nettle are support CTR mode, the
cipher-builtin doesn't support yet.

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

3 files changed, 34 insertions, 7 deletions

diff --git a/crypto/cipher-gcrypt.c b/crypto/cipher-gcrypt.c
index 05026c0..c550db9 100644
--- a/crypto/cipher-gcrypt.c
+++ b/crypto/cipher-gcrypt.c
@@ -59,6 +59,7 @@ struct QCryptoCipherGcrypt {
     gcry_cipher_hd_t handle;
     gcry_cipher_hd_t tweakhandle;
     size_t blocksize;
+    /* Initialization vector or Counter */
     uint8_t *iv;
 };
 
@@ -80,6 +81,9 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
     case QCRYPTO_CIPHER_MODE_CBC:
         gcrymode = GCRY_CIPHER_MODE_CBC;
         break;
+    case QCRYPTO_CIPHER_MODE_CTR:
+        gcrymode = GCRY_CIPHER_MODE_CTR;
+        break;
     default:
         error_setg(errp, "Unsupported cipher mode %s",
                    QCryptoCipherMode_lookup[mode]);
@@ -350,12 +354,21 @@ int qcrypto_cipher_setiv(QCryptoCipher *cipher,
     if (ctx->iv) {
         memcpy(ctx->iv, iv, niv);
     } else {
-        gcry_cipher_reset(ctx->handle);
-        err = gcry_cipher_setiv(ctx->handle, iv, niv);
-        if (err != 0) {
-            error_setg(errp, "Cannot set IV: %s",
-                   gcry_strerror(err));
-            return -1;
+        if (cipher->mode == QCRYPTO_CIPHER_MODE_CTR) {
+            err = gcry_cipher_setctr(ctx->handle, iv, niv);
+            if (err != 0) {
+                error_setg(errp, "Cannot set Counter: %s",
+                       gcry_strerror(err));
+                return -1;
+            }
+        } else {
+            gcry_cipher_reset(ctx->handle);
+            err = gcry_cipher_setiv(ctx->handle, iv, niv);
+            if (err != 0) {
+                error_setg(errp, "Cannot set IV: %s",
+                       gcry_strerror(err));
+                return -1;
+            }
         }
     }
 
diff --git a/crypto/cipher-nettle.c b/crypto/cipher-nettle.c
index 72d1069..cd094cd 100644
--- a/crypto/cipher-nettle.c
+++ b/crypto/cipher-nettle.c
@@ -28,6 +28,7 @@
 #include <nettle/cast128.h>
 #include <nettle/serpent.h>
 #include <nettle/twofish.h>
+#include <nettle/ctr.h>
 
 typedef void (*QCryptoCipherNettleFuncWrapper)(const void *ctx,
                                                size_t length,
@@ -186,7 +187,7 @@ struct QCryptoCipherNettle {
     QCryptoCipherNettleFuncNative alg_decrypt_native;
     QCryptoCipherNettleFuncWrapper alg_encrypt_wrapper;
     QCryptoCipherNettleFuncWrapper alg_decrypt_wrapper;
-
+    /* Initialization vector or Counter */
     uint8_t *iv;
     size_t blocksize;
 };
@@ -236,6 +237,7 @@ QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
     case QCRYPTO_CIPHER_MODE_ECB:
     case QCRYPTO_CIPHER_MODE_CBC:
     case QCRYPTO_CIPHER_MODE_XTS:
+    case QCRYPTO_CIPHER_MODE_CTR:
         break;
     default:
         error_setg(errp, "Unsupported cipher mode %s",
@@ -441,6 +443,12 @@ int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
                     ctx->iv, len, out, in);
         break;
 
+    case QCRYPTO_CIPHER_MODE_CTR:
+        ctr_crypt(ctx->ctx, ctx->alg_encrypt_native,
+                    ctx->blocksize, ctx->iv,
+                    len, out, in);
+        break;
+
     default:
         error_setg(errp, "Unsupported cipher mode %s",
                    QCryptoCipherMode_lookup[cipher->mode]);
@@ -480,6 +488,11 @@ int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
                     ctx->alg_encrypt_wrapper, ctx->alg_decrypt_wrapper,
                     ctx->iv, len, out, in);
         break;
+    case QCRYPTO_CIPHER_MODE_CTR:
+        ctr_crypt(ctx->ctx, ctx->alg_encrypt_native,
+                    ctx->blocksize, ctx->iv,
+                    len, out, in);
+        break;
 
     default:
         error_setg(errp, "Unsupported cipher mode %s",
diff --git a/crypto/cipher.c b/crypto/cipher.c
index cafb454..a9bca41 100644
--- a/crypto/cipher.c
+++ b/crypto/cipher.c
@@ -55,6 +55,7 @@ static bool mode_need_iv[QCRYPTO_CIPHER_MODE__MAX] = {
     [QCRYPTO_CIPHER_MODE_ECB] = false,
     [QCRYPTO_CIPHER_MODE_CBC] = true,
     [QCRYPTO_CIPHER_MODE_XTS] = true,
+    [QCRYPTO_CIPHER_MODE_CTR] = true,
 };