diff --git a/ykcs11/Makefile.am b/ykcs11/Makefile.am
index f94ef82..c635276 100644
--- a/ykcs11/Makefile.am
+++ b/ykcs11/Makefile.am
@@ -40,7 +40,7 @@ libykcs11_la_SOURCES += token_vendors.c token_vendor.h
 libykcs11_la_SOURCES += mechanisms.c mechanisms.h
 libykcs11_la_SOURCES += yubico_slot.c yubico_slot.h yubico_token.c yubico_token.h
 libykcs11_la_SOURCES += utils.c utils.h
-libykcs11_la_SOURCES += openssl_utils.c openssl_utils.h
+libykcs11_la_SOURCES += openssl_utils.c openssl_utils.h openssl_types.h
 libykcs11_la_SOURCES += objects.c objects.h obj_types.h
 
 #internal.h
diff --git a/ykcs11/mechanisms.c b/ykcs11/mechanisms.c
index 0d3e30e..ec23cf9 100644
--- a/ykcs11/mechanisms.c
+++ b/ykcs11/mechanisms.c
@@ -53,8 +53,6 @@ CK_BBOOL is_RSA_mechanism(CK_MECHANISM_TYPE m) {
   case CKM_RSA_PKCS:
   case CKM_RSA_9796:
   case CKM_RSA_X_509:
-  case CKM_MD2_RSA_PKCS:
-  case CKM_MD5_RSA_PKCS:
   case CKM_SHA1_RSA_PKCS:
 //  case CKM_SHA224_RSA_PKCS:
   case CKM_SHA256_RSA_PKCS:
@@ -85,15 +83,60 @@ CK_BBOOL is_RSA_mechanism(CK_MECHANISM_TYPE m) {
   return CK_FALSE;
 }
 
-CK_RV apply_sign_mechanism(CK_MECHANISM_PTR m, CK_BYTE_PTR in, CK_ULONG in_len,
-                           CK_BYTE_PTR out, CK_ULONG out_len, CK_ULONG key_len) {
-  switch (m->mechanism) {
+CK_RV apply_sign_mechanism_init(op_info_t *op_info) {
+
+    if (op_info->type != YKCS11_SIGN)
+      return CKR_FUNCTION_FAILED;
+
+    switch (op_info->mechanism.mechanism) {
+    case CKM_RSA_PKCS:
+      // No hash required for this mechanism
+      return CKR_OK;
+
+    case CKM_RSA_PKCS_PSS:  // TODO
+      return CKR_FUNCTION_FAILED;
+
+    case CKM_RSA_X_509:
+      // No hash required for this mechanism
+      return CKR_OK;
+
+    case CKM_SHA1_RSA_PKCS:
+    case CKM_ECDSA_SHA1:
+      return do_md_init(YKCS11_SHA1, &op_info->op.sign.md_ctx);
+
+    case CKM_SHA256_RSA_PKCS:
+      return do_md_init(YKCS11_SHA256, &op_info->op.sign.md_ctx);
+
+    case CKM_SHA384_RSA_PKCS:
+      return do_md_init(YKCS11_SHA384, &op_info->op.sign.md_ctx);
+
+    case CKM_SHA512_RSA_PKCS:
+      return do_md_init(YKCS11_SHA512, &op_info->op.sign.md_ctx);
+
+    case CKM_ECDSA:
+      return CKR_FUNCTION_FAILED; // TODO: but no hash needed
+
+    default:
+      CKR_FUNCTION_FAILED;
+  }
+
+    // Never reached
+    return CKR_FUNCTION_FAILED;
+}
+
+CK_RV apply_sign_mechanism_update(op_info_t *op_info, CK_BYTE_PTR in, CK_ULONG in_len) {
+  CK_RV rv;
+
+  if (op_info->type != YKCS11_SIGN)
+    return CKR_FUNCTION_FAILED;
+
+  switch (op_info->mechanism.mechanism) {
   case CKM_RSA_PKCS:
-    return do_pkcs_t1(in, in_len, out, out_len, key_len);
+    return CKR_OK;
 
   case CKM_RSA_PKCS_PSS:
     return CKR_FUNCTION_FAILED;
-    
+
   case CKM_RSA_X_509:
     return CKR_OK;
 
@@ -101,7 +144,57 @@ CK_RV apply_sign_mechanism(CK_MECHANISM_PTR m, CK_BYTE_PTR in, CK_ULONG in_len,
   case CKM_SHA256_RSA_PKCS:
   case CKM_SHA384_RSA_PKCS:
   case CKM_SHA512_RSA_PKCS:
+  case CKM_ECDSA_SHA1:
+    rv = do_md_update(op_info->op.sign.md_ctx, in, in_len);
+    if (rv != CKR_OK)
+      return CKR_FUNCTION_FAILED;
+
+    return CKR_OK;
+
+  case CKM_ECDSA:
+    return CKR_FUNCTION_FAILED;
+
+  default:
+    return CKR_FUNCTION_FAILED;
+  }
+
+}
+
+
+CK_RV apply_sign_mechanism_finalize(op_info_t *op_info) {
+
+  CK_RV rv;
+
+  if (op_info->type != YKCS11_SIGN)
+    return CKR_FUNCTION_FAILED;
+
+  switch (op_info->mechanism.mechanism) {
+  case CKM_RSA_PKCS_PSS:
+    return CKR_FUNCTION_FAILED;
+
+  case CKM_RSA_X_509:
+    return CKR_OK;
+
+  case CKM_SHA1_RSA_PKCS:
+  case CKM_SHA256_RSA_PKCS:
+  case CKM_SHA384_RSA_PKCS:
+  case CKM_SHA512_RSA_PKCS:
+  case CKM_ECDSA_SHA1:
+    // Finalize the hash if needed and add digest info
+    rv = do_md_finalize(op_info->op.sign.md_ctx, CK_TRUE, op_info->buf, &op_info->buf_len);
+    if (rv != CKR_OK)
+      return CKR_FUNCTION_FAILED;
+    fprintf(stderr, "The hashed value is %lu long and looks like\n", op_info->buf_len);
+    dump_hex(op_info->buf, op_info->buf_len, stderr, CK_TRUE);
+
+  case CKM_RSA_PKCS:
+    // And compute padding for all pkcs1 variants
+    return do_pkcs_t1(op_info->buf, op_info->buf_len, op_info->buf, sizeof(op_info->buf), op_info->op.sign.key_len);
+
+  case CKM_ECDSA:
+    return CKR_FUNCTION_FAILED;
+
+  default:
     return CKR_FUNCTION_FAILED;
   }
-  
 }
diff --git a/ykcs11/mechanisms.h b/ykcs11/mechanisms.h
index cb4130d..846ff50 100644
--- a/ykcs11/mechanisms.h
+++ b/ykcs11/mechanisms.h
@@ -3,11 +3,11 @@
 
 #include "ykcs11.h"
 
-
-CK_RV check_sign_mechanism(const ykcs11_session_t *s, CK_MECHANISM_PTR m);
+CK_RV    check_sign_mechanism(const ykcs11_session_t *s, CK_MECHANISM_PTR m);
 CK_BBOOL is_RSA_mechanism(CK_MECHANISM_TYPE m);
 
-CK_RV apply_sign_mechanism(CK_MECHANISM_PTR m, CK_BYTE_PTR in, CK_ULONG in_len,
-                           CK_BYTE_PTR out, CK_ULONG out_len, CK_ULONG key_len);
+CK_RV apply_sign_mechanism_init(op_info_t *op_info);
+CK_RV apply_sign_mechanism_update(op_info_t *op_info, CK_BYTE_PTR in, CK_ULONG in_len);
+CK_RV apply_sign_mechanism_finalize(op_info_t *op_info);
 
 #endif
diff --git a/ykcs11/openssl_types.h b/ykcs11/openssl_types.h
new file mode 100644
index 0000000..b56f934
--- /dev/null
+++ b/ykcs11/openssl_types.h
@@ -0,0 +1,22 @@
+#ifndef OPENSSL_TYPES_H
+#define OPENSSL_TYPES_H
+
+#include <openssl/x509.h>
+#include <openssl/evp.h>
+#include <openssl/rsa.h>
+#include <openssl/ec.h>
+
+typedef enum {
+  YKCS11_NO_HASH,
+  YKCS11_SHA1,
+  //YKCS11_SHA224,
+  YKCS11_SHA256,
+  YKCS11_SHA384,
+  YKCS11_SHA512,
+  //YKCS11_RIPEMD128_RSA_PKCS,
+  //YKCS11_RIPEMD160
+} hash_t;
+
+typedef EVP_MD_CTX ykcs11_md_ctx_t;
+
+#endif
diff --git a/ykcs11/openssl_utils.c b/ykcs11/openssl_utils.c
index afdfcf1..cd503e7 100644
--- a/ykcs11/openssl_utils.c
+++ b/ykcs11/openssl_utils.c
@@ -139,3 +139,77 @@ CK_RV do_pkcs_t1(CK_BYTE_PTR in, CK_ULONG in_len, CK_BYTE_PTR out, CK_ULONG out_
 
   return CKR_OK;
 }
+
+CK_RV do_md_init(hash_t hash, ykcs11_md_ctx_t **ctx) {
+
+  const EVP_MD *md;
+
+  switch (hash) {
+  case YKCS11_NO_HASH:
+    return CKR_FUNCTION_FAILED;
+
+  case YKCS11_SHA1:
+    md = EVP_sha1();
+    break;
+
+    //case YKCS11_SHA224:
+
+  case YKCS11_SHA256:
+    md = EVP_sha256();
+    break;
+
+  case YKCS11_SHA384:
+    md = EVP_sha384();
+    break;
+
+  case YKCS11_SHA512:
+    md = EVP_sha512();
+    break;
+
+  //case YKCS11_RIPEMD128_RSA_PKCS_HASH:
+  //case YKCS11_RIPEMD160_HASH:
+
+  default:
+    return CKR_FUNCTION_FAILED;
+  }
+
+  *ctx = EVP_MD_CTX_create();
+
+  // The OpenSSL function above never fail
+  if (EVP_DigestInit_ex(*ctx, md, NULL) == 0) {
+    EVP_MD_CTX_destroy(*ctx);
+    return CKR_FUNCTION_FAILED;
+  }
+
+  return CKR_OK;
+}
+
+CK_RV do_md_update(ykcs11_md_ctx_t *ctx, CK_BYTE_PTR in, CK_ULONG in_len) {
+
+  return EVP_DigestUpdate(ctx, in, in_len) == 1 ? CKR_OK : CKR_FUNCTION_FAILED;
+
+}
+
+CK_RV do_md_finalize(ykcs11_md_ctx_t *ctx, CK_BBOOL di, CK_BYTE_PTR out, CK_ULONG_PTR out_len) {
+
+  int rv;
+  bool rv2;
+  unsigned int len;
+
+  // Finalize digest and store result
+  rv = EVP_DigestFinal_ex(ctx, out, (unsigned int *)out_len);
+  // Check wheter digest info is required
+  if (di == CK_TRUE)
+    rv2 = prepare_rsa_signature(out, *out_len, out, &len, EVP_MD_CTX_type(ctx));
+
+  // Destroy the md context
+  EVP_MD_CTX_destroy(ctx);
+
+  // Error if either of the previous calls failed
+  if (rv != 1 || !rv2)
+    return CKR_FUNCTION_FAILED;
+
+  *out_len = len;
+
+  return CKR_OK;
+}
diff --git a/ykcs11/openssl_utils.h b/ykcs11/openssl_utils.h
index 00bff66..a82b340 100644
--- a/ykcs11/openssl_utils.h
+++ b/ykcs11/openssl_utils.h
@@ -1,10 +1,12 @@
 #ifndef OPENSSL_UTIL_H
 #define OPENSSL_UTIL_H
 
-#include <openssl/x509.h>
-#include <openssl/evp.h>
-#include <openssl/rsa.h>
-#include <openssl/ec.h>
+/* #include <openssl/x509.h> */
+/* #include <openssl/evp.h> */
+/* #include <openssl/rsa.h> */
+/* #include <openssl/ec.h> */
+
+#include "openssl_types.h"
 #include "pkcs11t.h"
 
 CK_RV do_store_cert(CK_BYTE_PTR data, CK_ULONG len, X509 **cert);
@@ -18,4 +20,8 @@ CK_RV       free_key(EVP_PKEY *key);
 
 CK_RV do_pkcs_t1(CK_BYTE_PTR in, CK_ULONG in_len, CK_BYTE_PTR out, CK_ULONG out_len, CK_ULONG key_len);
 
+CK_RV do_md_init(hash_t hash, ykcs11_md_ctx_t **ctx);
+CK_RV do_md_update(ykcs11_md_ctx_t *ctx, CK_BYTE_PTR in, CK_ULONG in_len);
+CK_RV do_md_finalize(ykcs11_md_ctx_t *ctx, CK_BBOOL di, CK_BYTE_PTR out, CK_ULONG_PTR out_len);
+
 #endif
diff --git a/ykcs11/ykcs11.c b/ykcs11/ykcs11.c
index 781bdaf..51dbc12 100644
--- a/ykcs11/ykcs11.c
+++ b/ykcs11/ykcs11.c
@@ -7,6 +7,7 @@
 #include "obj_types.h"
 #include "utils.h"
 #include "mechanisms.h"
+#include "openssl_types.h"
 
 #define D(x) do {                                                     \
     printf ("debug: %s:%d (%s): ", __FILE__, __LINE__, __FUNCTION__); \
@@ -58,16 +59,10 @@ static struct {
   piv_obj_id_t    *objects;
 } find_obj;
 
-/*static piv_obj_id_t token_objects[PIV_CERT_OBJ_LAST]; // TODO: tide this up, also build at runtime (during open session)? And include inside a session struct?
-  static CK_ULONG n_token_objects = 0;*/
+op_info_t op_info;
 
-static struct {
-  CK_BBOOL     active;
-  CK_MECHANISM mechanism;
-  CK_ULONG     key;
-  CK_ULONG     key_len;
-  CK_BYTE      algo;
-} sign_info;
+/*static piv_obj_id_t token_objects[PIV_CERT_OBJ_LAST]; // TODO: tidy this up, also build at runtime (during open session)? And include inside a session struct?
+  static CK_ULONG n_token_objects = 0;*/
 
 extern CK_FUNCTION_LIST function_list; // TODO: check all return values
 
@@ -87,7 +82,7 @@ CK_DEFINE_FUNCTION(CK_RV, C_Initialize)(
     return CKR_CRYPTOKI_ALREADY_INITIALIZED;
 
   if (ykpiv_init(&piv_state, YKCS11_DBG) != YKPIV_OK) {
-    DBG(("Unable to initialize YubiKey"));
+    DBG(("Unable to initialize libykpiv"));
     return CKR_FUNCTION_FAILED; // TODO: better error?
   }
 
@@ -1247,7 +1242,7 @@ CK_DEFINE_FUNCTION(CK_RV, C_SignInit)(
     DBG(("Mechanism %lu is not supported either by the token or the slot", pMechanism->mechanism));
     return CKR_MECHANISM_INVALID; // TODO: also the key has a list of allowed mechanisms, check that
   }
-  memcpy(&sign_info.mechanism, pMechanism, sizeof(CK_MECHANISM));
+  memcpy(&op_info.mechanism, pMechanism, sizeof(CK_MECHANISM));
 
   //  Get key algorithm
   if (get_attribute(&session, hKey, template) != CKR_OK) {
@@ -1265,12 +1260,12 @@ CK_DEFINE_FUNCTION(CK_RV, C_SignInit)(
       return CKR_KEY_HANDLE_INVALID;
     }
 
-    sign_info.key_len = key_len;
+    op_info.op.sign.key_len = key_len;
 
     if (key_len == 1024)
-      sign_info.algo = YKPIV_ALGO_RSA1024;
+      op_info.op.sign.algo = YKPIV_ALGO_RSA1024;
     else
-      sign_info.algo = YKPIV_ALGO_RSA2048;
+      op_info.op.sign.algo = YKPIV_ALGO_RSA2048;
 
   }
   else {
@@ -1282,33 +1277,38 @@ CK_DEFINE_FUNCTION(CK_RV, C_SignInit)(
 
     // The buffer contains an uncompressed point of the form 04, x, y
     // TODO: is this a fine representation for an EC public key?
-    sign_info.key_len = ((template[2].ulValueLen - 1) / 2) * 8;
+    op_info.op.sign.key_len = ((template[2].ulValueLen - 1) / 2) * 8;
 
-    if (sign_info.key_len == 256)
-      sign_info.algo = YKPIV_ALGO_ECCP256;
+    if (op_info.op.sign.key_len == 256)
+      op_info.op.sign.algo = YKPIV_ALGO_ECCP256;
     /*else
-      sign_info.algo = ;*/
+      op_info.algo = ;*/
   }
 
-  DBG(("Key length is %lu bit", sign_info.key_len));
+  //op_info.hash = get_mechanism_hash(pMechanism->mechanism);
 
-  sign_info.key = piv_2_ykpiv(hKey);
-  if (sign_info.key == 0) {
+  DBG(("Key length is %lu bit", op_info.op.sign.key_len));
+
+  op_info.op.sign.key = piv_2_ykpiv(hKey);
+  if (op_info.op.sign.key == 0) {
     DBG(("Incorrect key %lu", hKey));
     return CKR_KEY_HANDLE_INVALID;
   }
 
-  DBG(("Algorithm is %d", sign_info.algo));
+  DBG(("Algorithm is %d", op_info.op.sign.algo));
   // Make sure that both mechanism and key have the same algorithm
-  if ((is_RSA_mechanism(pMechanism->mechanism) && sign_info.algo == YKPIV_ALGO_ECCP256) ||
-      (!is_RSA_mechanism(pMechanism->mechanism) && (sign_info.algo != YKPIV_ALGO_ECCP256))) {
+  if ((is_RSA_mechanism(pMechanism->mechanism) && op_info.op.sign.algo == YKPIV_ALGO_ECCP256) ||
+      (!is_RSA_mechanism(pMechanism->mechanism) && (op_info.op.sign.algo != YKPIV_ALGO_ECCP256))) {
     DBG(("Key and mechanism algorithm do not match"));
     return CKR_ARGUMENTS_BAD;
   }
 
-  // TODO: also allocate some space for the signature in case of multipart
+  op_info.type = YKCS11_SIGN;
 
-  sign_info.active = CK_TRUE;
+  if (apply_sign_mechanism_init(&op_info) != CKR_OK) {
+    DBG(("Unable to initialize signing operation"));
+    return CKR_FUNCTION_FAILED;
+  }
 
   DOUT;
   return CKR_OK;
@@ -1323,28 +1323,32 @@ CK_DEFINE_FUNCTION(CK_RV, C_Sign)(
 )
 {
   DIN;
-  CK_BYTE  buf[YKCS11_MAX_SIG_BUF_LEN];
-  CK_ULONG buf_len = sizeof(buf);
 
-  if (sign_info.active == CK_FALSE)
+  if (op_info.type == YKCS11_NOOP)
     return CKR_OPERATION_NOT_INITIALIZED;
 
-  // TODO: check conditions
-  ykpiv_rc r;
-  CK_CHAR algo;
+  if (op_info.type != YKCS11_SIGN)
+    return CKR_OPERATION_ACTIVE;
+
+  // TODO: check other conditions
+  ykpiv_rc r; // TODO: delete this
 
   DBG(("Sending %lu bytes to sign", ulDataLen));
   dump_hex(pData, ulDataLen, stderr, CK_TRUE);
 
-  if (apply_sign_mechanism(&sign_info.mechanism, pData, ulDataLen, buf, buf_len, 2048 / 8) != CKR_OK) {
-    DBG(("Unable to apply padding scheme"));
+  if (apply_sign_mechanism_update(&op_info, pData, ulDataLen) != CKR_OK) {
+    DBG(("Unable to perform signing operation step"));
+    return CKR_FUNCTION_FAILED;
+  }
+
+  if (apply_sign_mechanism_finalize(&op_info) != CKR_OK) {
+    DBG(("Unable to finalize signing operation"));
     return CKR_FUNCTION_FAILED;
   }
-  memcpy(buf, pData, ulDataLen); // ykpiv does padding already
   //dump_hex(buf, 256, stderr, CK_TRUE);
   //*pulSignatureLen = 256;
-  DBG(("Using key %lx", sign_info.key)); // TODO: test what happens if there is no key on the card
-  if ((r = ykpiv_sign_data(piv_state, buf, ulDataLen, pSignature, pulSignatureLen, sign_info.algo, sign_info.key)) != YKPIV_OK) {
+  DBG(("Using key %lx", op_info.op.sign.key)); // TODO: test what happens if there is no key on the card
+  if ((r = ykpiv_sign_data(piv_state, op_info.buf, ulDataLen, pSignature, pulSignatureLen, op_info.op.sign.algo, op_info.op.sign.key)) != YKPIV_OK) {
       DBG(("Sign error, %s", ykpiv_strerror(r)));
     return CKR_FUNCTION_FAILED;
   }
diff --git a/ykcs11/ykcs11.h b/ykcs11/ykcs11.h
index cfa22da..fc20bb0 100644
--- a/ykcs11/ykcs11.h
+++ b/ykcs11/ykcs11.h
@@ -3,8 +3,11 @@
 
 #include "pkcs11t.h"
 #include "obj_types.h"
+#include "openssl_types.h"
 #include "vendors.h"
 
+#define  YKCS11_OP_BUFSIZE  4096
+
 typedef struct {
   vendor_id_t   vid;
   CK_TOKEN_INFO info;
@@ -25,4 +28,41 @@ typedef struct {
   ykcs11_slot_t     *slot;
 } ykcs11_session_t;
 
+
+typedef enum {
+  YKCS11_NOOP,
+  YKCS11_SIGN,
+  YKCS11_HASH,
+  YKCS11_DECRYPT
+} ykcs11_op_type_t;
+
+typedef struct {
+  ykcs11_md_ctx_t *md_ctx;
+  CK_BYTE         algo;
+  CK_ULONG        key;
+  CK_ULONG        key_len;
+} sign_info_t;
+
+typedef struct {
+  CK_BYTE todo;
+} hash_info_t;
+
+typedef struct {
+  CK_BYTE todo;
+} decrypt_info_t;
+
+typedef union {
+  sign_info_t    sign;
+  hash_info_t    hash;
+  decrypt_info_t decrypt;
+} op_t;
+
+typedef struct {
+  ykcs11_op_type_t type;
+  CK_MECHANISM     mechanism;
+  op_t             op;
+  CK_BYTE          buf[YKCS11_OP_BUFSIZE];
+  CK_ULONG         buf_len;
+} op_info_t;
+
 #endif