Make the crc32 hash provider correctly chain multiple input buffers,

so that it returns the same result if you pass it one big buffer or
many small buffers containing the same data.  To do this, change the
contract of mit_crc32 so that the cksum parameter is in-out.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@23386 dc483132-0cff-0310-8789-dd5450dbe970

5 files changed, 13 insertions, 12 deletions

diff --git a/src/lib/crypto/builtin/hash_provider/hash_crc32.c b/src/lib/crypto/builtin/hash_provider/hash_crc32.c
index e748c98..58efffe 100644
--- a/src/lib/crypto/builtin/hash_provider/hash_crc32.c
+++ b/src/lib/crypto/builtin/hash_provider/hash_crc32.c
@@ -33,17 +33,15 @@ static krb5_error_code
 k5_crc32_hash(unsigned int icount, const krb5_data *input,
               krb5_data *output)
 {
-    unsigned long c, cn;
+    unsigned long c;
     unsigned int i;
 
     if (output->length != CRC32_CKSUM_LENGTH)
         return(KRB5_CRYPTO_INTERNAL);
 
     c = 0;
-    for (i=0; i<icount; i++) {
-        mit_crc32(input[i].data, input[i].length, &cn);
-        c ^= cn;
-    }
+    for (i=0; i<icount; i++)
+        mit_crc32(input[i].data, input[i].length, &c);
 
     store_32_le(c, output->data);
     return(0);
diff --git a/src/lib/crypto/crypto_tests/t_crc.c b/src/lib/crypto/crypto_tests/t_crc.c
index 6d06334..69a6468 100644
--- a/src/lib/crypto/crypto_tests/t_crc.c
+++ b/src/lib/crypto/crypto_tests/t_crc.c
@@ -121,6 +121,7 @@ timetest(unsigned int nblk, unsigned int blksiz)
         block[i] = i % 256;
     times(&before);
     for (i = 0; i < nblk; i++) {
+        cksum = 0;
         mit_crc32(block + i * blksiz, blksiz, &cksum);
     }
 
@@ -136,6 +137,7 @@ timetest(unsigned int nblk, unsigned int blksiz)
 #ifdef CRC32_SHIFT4
     times(&before);
     for (i = 0; i < nblk; i++) {
+        cksum = 0;
         mit_crc32_shift4(block + i * blksiz, blksiz, &cksum);
     }
     times(&after);
@@ -185,11 +187,13 @@ verify(void)
         case STR:
             len = strlen(trial.data);
             typestr = "STR";
+            cksum = 0;
             mit_crc32(trial.data, len, &cksum);
             break;
         case HEX:
             typestr = "HEX";
             gethexstr(trial.data, &len, buf, 4);
+            cksum = 0;
             mit_crc32(buf, len, &cksum);
             break;
         default:
diff --git a/src/lib/crypto/krb/crc32/crc-32.h b/src/lib/crypto/krb/crc32/crc-32.h
index 95001f5..5c28b8b 100644
--- a/src/lib/crypto/krb/crc32/crc-32.h
+++ b/src/lib/crypto/krb/crc32/crc-32.h
@@ -60,6 +60,7 @@
 
 #define CRC32_CKSUM_LENGTH      4
 
+/* c is in-out to allow chaining; initialize to 0. */
 void
 mit_crc32 (krb5_pointer in, size_t in_length, unsigned long *c);
 
diff --git a/src/lib/crypto/krb/crc32/crc32.c b/src/lib/crypto/krb/crc32/crc32.c
index 4909798..ef364f3 100644
--- a/src/lib/crypto/krb/crc32/crc32.c
+++ b/src/lib/crypto/krb/crc32/crc32.c
@@ -151,7 +151,7 @@ void
 mit_crc32(krb5_pointer in, size_t in_length, unsigned long *cksum)
 {
     register u_char *data;
-    register u_long c = 0;
+    register u_long c = *cksum;
     register int idx;
     size_t i;
 
@@ -178,7 +178,7 @@ void
 mit_crc32_shift4(krb5_pointer in, size_t in_length, unsigned long *cksum)
 {
     register unsigned char *data, b;
-    register unsigned long c = 0;
+    register unsigned long c = *cksum;
     size_t i;
 
     data = (u_char *)in;
diff --git a/src/lib/crypto/openssl/hash_provider/hash_crc32.c b/src/lib/crypto/openssl/hash_provider/hash_crc32.c
index e748c98..58efffe 100644
--- a/src/lib/crypto/openssl/hash_provider/hash_crc32.c
+++ b/src/lib/crypto/openssl/hash_provider/hash_crc32.c
@@ -33,17 +33,15 @@ static krb5_error_code
 k5_crc32_hash(unsigned int icount, const krb5_data *input,
               krb5_data *output)
 {
-    unsigned long c, cn;
+    unsigned long c;
     unsigned int i;
 
     if (output->length != CRC32_CKSUM_LENGTH)
         return(KRB5_CRYPTO_INTERNAL);
 
     c = 0;
-    for (i=0; i<icount; i++) {
-        mit_crc32(input[i].data, input[i].length, &cn);
-        c ^= cn;
-    }
+    for (i=0; i<icount; i++)
+        mit_crc32(input[i].data, input[i].length, &c);
 
     store_32_le(c, output->data);
     return(0);