Change CTS CS3 (Kerberos) so that it accepts a 16 byte input block

Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16286)

1 files changed, 10 insertions, 2 deletions

diff --git a/providers/implementations/ciphers/cipher_cts.c b/providers/implementations/ciphers/cipher_cts.c
index 3e880931c1..5732ae1990 100644
--- a/providers/implementations/ciphers/cipher_cts.c
+++ b/providers/implementations/ciphers/cipher_cts.c
@@ -195,9 +195,13 @@ static size_t cts128_cs3_encrypt(PROV_CIPHER_CTX *ctx, const unsigned char *in,
     aligned_16bytes tmp_in;
     size_t residue;
 
-    if (len <= CTS_BLOCK_SIZE)  /* CS3 requires 2 blocks */
+    if (len < CTS_BLOCK_SIZE)  /* CS3 requires at least one block */
         return 0;
 
+    /* If we only have one block then just process the aligned block */
+    if (len == CTS_BLOCK_SIZE)
+        return ctx->hw->cipher(ctx, out, in, len) ? len : 0;
+
     residue = len % CTS_BLOCK_SIZE;
     if (residue == 0)
         residue = CTS_BLOCK_SIZE;
@@ -231,9 +235,13 @@ static size_t cts128_cs3_decrypt(PROV_CIPHER_CTX *ctx, const unsigned char *in,
     aligned_16bytes mid_iv, ct_mid, pt_last;
     size_t residue;
 
-    if (len <= CTS_BLOCK_SIZE) /* CS3 requires 2 blocks */
+    if (len < CTS_BLOCK_SIZE) /* CS3 requires at least one block */
         return 0;
 
+    /* If we only have one block then just process the aligned block */
+    if (len == CTS_BLOCK_SIZE)
+        return ctx->hw->cipher(ctx, out, in, len) ? len : 0;
+
     /* Process blocks at the start - but leave the last 2 blocks */
     residue = len % CTS_BLOCK_SIZE;
     if (residue == 0)