diff --git a/client/Makefile b/client/Makefile
index 2f5478b39..c0f87e0a7 100644
--- a/client/Makefile
+++ b/client/Makefile
@@ -558,6 +558,7 @@ SRCS =  aiddesfire.c \
 		fido/cbortools.c \
 		fido/fidocore.c \
 		cipurse/cipursecore.c \
+		cipurse/cipursecrypto.c \
 		fileutils.c \
 		flash.c \
 		generator.c \
diff --git a/client/src/cipurse/cipursecrypto.c b/client/src/cipurse/cipursecrypto.c
index 0f928ea1e..e020676c6 100644
--- a/client/src/cipurse/cipursecrypto.c
+++ b/client/src/cipurse/cipursecrypto.c
@@ -8,7 +8,7 @@
 // CIPURSE crypto primitives
 //-----------------------------------------------------------------------------
 
-#include "cipursecore.h"
+#include "cipursecrypto.h"
 
 #include "commonutil.h"  // ARRAYLEN
 #include "comms.h"       // DropField
@@ -20,4 +20,46 @@
 #include "ui.h"
 #include "util.h"
 
+void CipurseClearContext(CipurseContext *ctx) {
+    if (ctx == NULL)
+        return;
+    
+    memset(ctx, 0, sizeof(CipurseContext));
+}
 
+void CipurseSetKey(CipurseContext *ctx, uint8_t keyId, uint8_t *key) {
+    if (ctx == NULL)
+        return;
+    
+    CipurseClearContext(ctx);
+    
+    ctx->keyId = keyId;
+    memcpy(ctx->key, key, member_size(CipurseContext, key));
+}
+
+void CipurseSetRandomFromPICC(CipurseContext *ctx, uint8_t *random) {
+    if (ctx == NULL)
+        return;
+      
+    memcpy(ctx->RP, random, member_size(CipurseContext, RP));
+    memcpy(ctx->rP, random + member_size(CipurseContext, RP), member_size(CipurseContext, rP));
+}
+
+void CipurseSetRandomHost(CipurseContext *ctx) {
+    memset(ctx->RT, 0x10, member_size(CipurseContext, RT));
+    memset(ctx->rT, 0x20, member_size(CipurseContext, rT));
+}
+
+void CipurseAuthenticateHost(CipurseContext *ctx) {
+    if (ctx == NULL)
+        return;
+    
+/*        RT = Random.nextBytes(16)
+        rT = Random.nextBytes(6)
+
+        val cP = generateK0AndGetCp(key, RP, rP, RT, rT) ?: return Pair(null, null)
+
+        return Pair(cP + RT + rT, generateCT(RT))*/
+        
+        
+}
diff --git a/client/src/cipurse/cipursecrypto.h b/client/src/cipurse/cipursecrypto.h
index f2e0dbfa2..07019f6ca 100644
--- a/client/src/cipurse/cipursecrypto.h
+++ b/client/src/cipurse/cipursecrypto.h
@@ -13,28 +13,37 @@
 
 #include "common.h"
 
+#define member_size(type, member) sizeof(((type *)0)->member)
+
 enum CipurseChannelSecurityLevel {
     CPSNone,
     CPSPlain,
     CPSMACed,
     CPSEncrypted
-}
+};
 
-struct CipurseSession {
-    uint8_t keyId,
-    uint8_t[16] key,
+typedef struct CipurseContextS {
+    uint8_t keyId;
+    uint8_t key[16];
     
-    uint8_t[16] RP,
-    uint8_t[6]  rP,
-    uint8_t[16] RT,
-    uint8_t[6]  rT,
+    uint8_t RP[16];
+    uint8_t rP[6];
+    uint8_t RT[16];
+    uint8_t rT[6];
     
-    uint8_t[16] k0,
-    uint8_t[16] cP,
+    uint8_t frameKey0[16];
+    uint8_t cP[16];
     
-    uint8_t[16] frameKey,
-    uint8_t[16] frameKey1
-}
+    uint8_t frameKey[16];
+    uint8_t frameKeyNext[16];
+} CipurseContext;
+
+void CipurseClearContext(CipurseContext *ctx);
+void CipurseSetKey(CipurseContext *ctx, uint8_t keyId, uint8_t *key);
+void CipurseSetRandomFromPICC(CipurseContext *ctx, uint8_t *random);
+void CipurseSetRandomHost(CipurseContext *ctx);
+
+void CipurseAuthenticateHost(CipurseContext *ctx);
 
 
 
diff --git a/client/src/cmdhfcipurse.c b/client/src/cmdhfcipurse.c
index a1e9176b1..1806e4be4 100644
--- a/client/src/cmdhfcipurse.c
+++ b/client/src/cmdhfcipurse.c
@@ -24,6 +24,7 @@
 #include "cliparser.h"
 #include "cmdhfcipurse.h"
 #include "cipurse/cipursecore.h"
+#include "cipurse/cipursecrypto.h"
 #include "ui.h"
 #include "cmdhf14a.h"
 #include "cmdtrace.h"
@@ -93,6 +94,10 @@ static int CmdHFCipurseAuth(const char *Cmd) {
         DropField();
         return PM3_ESOFT;
     }
+    
+    uint8_t key[] = {0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73, 0x73};
+    CipurseContext ctx = {0};
+    CipurseSetKey(&ctx, 1, key);
 
     res = CIPURSEChallenge(buf, sizeof(buf), &len, &sw);
     if (res != 0 || len != 0x16) {
@@ -100,6 +105,9 @@ static int CmdHFCipurseAuth(const char *Cmd) {
         DropField();
         return PM3_ESOFT;
     }
+    CipurseSetRandomFromPICC(&ctx, buf);
+    
+    
     
     
     DropField();