diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5449648..7b1cbc9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -78,6 +78,7 @@ target_sources(hsm2040 PUBLIC
         ${CMAKE_CURRENT_LIST_DIR}/OpenSC/src/libopensc/sc.c
         ${CMAKE_CURRENT_LIST_DIR}/OpenSC/src/libopensc/ctx.c
         ${CMAKE_CURRENT_LIST_DIR}/OpenSC/src/libopensc/pkcs15-sc-hsm.c
+        ${CMAKE_CURRENT_LIST_DIR}/OpenSC/src/libopensc/padding.c
         )
 
 target_include_directories(hsm2040 PUBLIC
diff --git a/sc_hsm.c b/sc_hsm.c
index 8e40d44..3e51f0c 100644
--- a/sc_hsm.c
+++ b/sc_hsm.c
@@ -1161,6 +1161,42 @@ static int cmd_key_gen() {
     return SW_OK();
 }
 
+static int cmd_signature() {
+    uint8_t key_id = P1(apdu);
+    uint8_t p2 = P2(apdu);
+    mbedtls_md_type_t md = MBEDTLS_MD_NONE;
+    if (p2 == ALGO_RSA_PKCS1_SHA1 || ALGO_RSA_PSS_SHA1 || ALGO_EC_SHA1)
+        md = MBEDTLS_MD_SHA1;
+    else if (p2 == ALGO_RSA_PKCS1_SHA256 || p2 == ALGO_RSA_PSS_SHA256 || p2 == ALGO_EC_SHA256)
+        md = MBEDTLS_MD_SHA256;
+    else if (p2 == ALGO_EC_SHA224)
+        md = MBEDTLS_MD_SHA224;
+    if (p2 == ALGO_RSA_RAW || p2 == ALGO_RSA_PKCS1 || p2 == ALGO_RSA_PKCS1_SHA1 || p2 == ALGO_RSA_PKCS1_SHA256 || p2 == ALGO_RSA_PSS || p2 == ALGO_RSA_PSS_SHA1 || p2 == ALGO_RSA_PSS_SHA256) {
+        mbedtls_rsa_context ctx;
+        if (p2 == ALGO_RSA_PSS || p2 == ALGO_RSA_PSS_SHA1 || p2 == ALGO_RSA_PSS_SHA256) {
+            mbedtls_rsa_set_padding(&ctx, MBEDTLS_RSA_PKCS_V21, md);
+        }
+        else if (p2 == ALGO_RSA_PKCS1) { //DigestInfo attached
+            unsigned int algo;
+            if (sc_pkcs1_strip_digest_info_prefix(&algo, apdu.cmd_apdu_data, apdu.cmd_apdu_data_len, apdu.cmd_apdu_data, &apdu.cmd_apdu_data_len) != SC_SUCCESS) //gets the MD algo id and strips it off
+                return SW_EXEC_ERROR();
+            if (algo == SC_ALGORITHM_RSA_HASH_SHA1)
+                md = MBEDTLS_MD_SHA1;
+            else if (algo == SC_ALGORITHM_RSA_HASH_SHA224)
+                md = MBEDTLS_MD_SHA224;
+            else if (algo == SC_ALGORITHM_RSA_HASH_SHA256)
+                md = MBEDTLS_MD_SHA256;
+            else if (algo == SC_ALGORITHM_RSA_HASH_SHA384)
+                md = MBEDTLS_MD_SHA384;
+            else if (algo == SC_ALGORITHM_RSA_HASH_SHA512)
+                md = MBEDTLS_MD_SHA512;
+        }
+    }
+    else if (p2 == ALGO_EC_RAW || p2 == ALGO_EC_SHA1 || p2 == ALGO_EC_SHA224 || p2 == ALGO_EC_SHA256) {
+        
+    }
+}
+
 typedef struct cmd
 {
   uint8_t ins;
@@ -1175,6 +1211,7 @@ typedef struct cmd
 #define INS_INITIALIZE              0x50
 #define INS_IMPORT_DKEK             0x52
 #define INS_LIST_KEYS               0x58
+#define INS_SIGNATURE               0x68
 #define INS_CHALLENGE               0x84
 #define INS_SELECT_FILE				0xA4
 #define INS_READ_BINARY				0xB0
@@ -1197,6 +1234,7 @@ static const cmd_t cmds[] = {
     { INS_DELETE_FILE, cmd_delete_file },
     { INS_CHANGE_PIN, cmd_change_pin },
     { INS_KEY_GEN, cmd_key_gen },
+    { INS_SIGNATURE, cmd_signature },
     { 0x00, 0x0}
 };
 
diff --git a/sc_hsm.h b/sc_hsm.h
index e69171e..0f78722 100644
--- a/sc_hsm.h
+++ b/sc_hsm.h
@@ -42,6 +42,22 @@ extern const uint8_t sc_hsm_aid[];
 #define HSM_ERR_FILE_NOT_FOUND              -1003
 #define HSM_ERR_BLOCKED                     -1004
 
+#define ALGO_RSA_RAW			0x20		/* RSA signature with external padding */
+#define ALGO_RSA_DECRYPT		0x21		/* RSA decrypt */
+#define ALGO_RSA_PKCS1			0x30		/* RSA signature with DigestInfo input and PKCS#1 V1.5 padding */
+#define ALGO_RSA_PKCS1_SHA1		0x31		/* RSA signature with SHA-1 hash and PKCS#1 V1.5 padding */
+#define ALGO_RSA_PKCS1_SHA256	0x33		/* RSA signature with SHA-256 hash and PKCS#1 V1.5 padding */
+
+#define ALGO_RSA_PSS			0x40		/* RSA signature with external hash and PKCS#1 PSS padding*/
+#define ALGO_RSA_PSS_SHA1		0x41		/* RSA signature with SHA-1 hash and PKCS#1 PSS padding */
+#define ALGO_RSA_PSS_SHA256		0x43		/* RSA signature with SHA-256 hash and PKCS#1 PSS padding */
+
+#define ALGO_EC_RAW				0x70		/* ECDSA signature with hash input */
+#define ALGO_EC_SHA1			0x71		/* ECDSA signature with SHA-1 hash */
+#define ALGO_EC_SHA224			0x72		/* ECDSA signature with SHA-224 hash */
+#define ALGO_EC_SHA256			0x73		/* ECDSA signature with SHA-256 hash */
+#define ALGO_EC_DH				0x80        /* ECDH key derivation */
+
 extern int pin_reset_retries(const file_t *pin, bool);
 extern int pin_wrong_retry(const file_t *pin);