crypto: add crypto tests for single block DES-ECB and DES-CBC

The GNUTLS crypto provider doesn't support DES-ECB, only DES-CBC.
We can use the latter to simulate the former, if we encrypt only
1 block (8 bytes) of data at a time, using an all-zeros IV. This
is a very inefficient way to use the QCryptoCipher APIs, but
since the VNC authentication challenge is only 16 bytes, this
is acceptable. No other part of QEMU should be using DES. This
test case demonstrates the equivalence of ECB and CBC for the
single-block case.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

tests/unit/test-crypto-cipher.c

@@ -149,6 +149,29 @@ static QCryptoCipherTestData test_data[] = {
             "39f23369a9d9bacfa530e26304231461"
             "b2eb05e2c39be9fcda6c19078c6a9d1b",
     },
+    {
+        /*
+         * Testing 'password' as plaintext fits
+         * in single AES block, and gives identical
+         * ciphertext in ECB and CBC modes
+         */
+        .path = "/crypto/cipher/des-rfb-ecb-56-one-block",
+        .alg = QCRYPTO_CIPHER_ALG_DES_RFB,
+        .mode = QCRYPTO_CIPHER_MODE_ECB,
+        .key = "0123456789abcdef",
+        .plaintext = "70617373776f7264",
+        .ciphertext = "73fa80b66134e403",
+    },
+    {
+        /* See previous comment */
+        .path = "/crypto/cipher/des-rfb-cbc-56-one-block",
+        .alg = QCRYPTO_CIPHER_ALG_DES_RFB,
+        .mode = QCRYPTO_CIPHER_MODE_CBC,
+        .key = "0123456789abcdef",
+        .iv = "0000000000000000",
+        .plaintext = "70617373776f7264",
+        .ciphertext = "73fa80b66134e403",
+    },
     {
         .path = "/crypto/cipher/des-rfb-ecb-56",
         .alg = QCRYPTO_CIPHER_ALG_DES_RFB,