1 files changed, 110 insertions, 0 deletions
diff --git a/src/lib/crypto/openssl/hmac.c b/src/lib/crypto/openssl/hmac.c
new file mode 100644
index 0000000000..a5543c9773
--- /dev/null
+++ b/src/lib/crypto/openssl/hmac.c
@@ -0,0 +1,110 @@
+/*
+ */
+
+#include "k5-int.h"
+#include "aead.h"
+#include <openssl/hmac.h>
+#include <openssl/evp.h>
+
+/*
+ * the HMAC transform looks like:
+ *
+ * H(K XOR opad, H(K XOR ipad, text))
+ *
+ * where H is a cryptographic hash
+ * K is an n byte key
+ * ipad is the byte 0x36 repeated blocksize times
+ * opad is the byte 0x5c repeated blocksize times
+ * and text is the data being protected
+ */
+
+static const EVP_MD *
+map_digest(const struct krb5_hash_provider *hash)
+{
+    if (!strncmp(hash->hash_name, "SHA1",4))
+        return EVP_sha1();
+    else if (!strncmp(hash->hash_name, "MD5", 3))
+        return EVP_md5();
+    else if (!strncmp(hash->hash_name, "MD4", 3))
+        return EVP_md4();
+    else
+        return NULL;
+}
+
+krb5_error_code
+krb5_hmac(const struct krb5_hash_provider *hash, const krb5_keyblock *key,
+          unsigned int icount, const krb5_data *input, krb5_data *output)
+{
+    unsigned int i = 0, md_len = 0; 
+    unsigned char md[EVP_MAX_MD_SIZE];
+    HMAC_CTX c;
+    size_t hashsize, blocksize;
+
+    hashsize = hash->hashsize;
+    blocksize = hash->blocksize;
+
+    if (key->length > blocksize)
+        return(KRB5_CRYPTO_INTERNAL);
+    if (output->length < hashsize)
+        return(KRB5_BAD_MSIZE);
+    /* if this isn't > 0, then there won't be enough space in this
+       array to compute the outer hash */
+    if (icount == 0)
+        return(KRB5_CRYPTO_INTERNAL);
+
+    if (!map_digest(hash))
+        return(KRB5_CRYPTO_INTERNAL); // unsupported alg
+
+    HMAC_CTX_init(&c);
+    HMAC_Init(&c, key->contents, key->length, map_digest(hash));
+    for ( i = 0; i < icount; i++ ) {
+        HMAC_Update(&c,(const unsigned char*)input[i].data, input[i].length);
+    }
+    HMAC_Final(&c,(unsigned char *)md, &md_len);
+    if ( md_len <= output->length) {
+        output->length = md_len;
+        memcpy(output->data, md, output->length);
+    }
+    HMAC_CTX_cleanup(&c);
+    return 0;
+
+
+}
+
+krb5_error_code
+krb5int_hmac_iov(const struct krb5_hash_provider *hash, const krb5_keyblock *key,
+                 const krb5_crypto_iov *data, size_t num_data, krb5_data *output)
+{
+    krb5_data *sign_data;
+    size_t num_sign_data;
+    krb5_error_code ret;
+    size_t i, j;
+
+    /* Create a checksum over all the data to be signed */
+    for (i = 0, num_sign_data = 0; i < num_data; i++) {
+        const krb5_crypto_iov *iov = &data[i];
+
+        if (SIGN_IOV(iov))
+            num_sign_data++;
+    }
+
+    /* XXX cleanup to avoid alloc */
+    sign_data = (krb5_data *)calloc(num_sign_data, sizeof(krb5_data));
+    if (sign_data == NULL)
+        return ENOMEM;
+
+    for (i = 0, j = 0; i < num_data; i++) {
+        const krb5_crypto_iov *iov = &data[i];
+
+        if (SIGN_IOV(iov))
+            sign_data[j++] = iov->data;
+    }
+
+    /* caller must store checksum in iov as it may be TYPE_TRAILER or TYPE_CHECKSUM */
+    ret = krb5_hmac(hash, key, num_sign_data, sign_data, output);
+
+    free(sign_data);
+
+    return ret;
+}
+